and Anatomy of PET/CT

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© The Author(s), under exclusive license to Springer Nature Switzerland AG 2022
E. E. Kim et al. (eds.)Atlas and Anatomy of PET/MRI, PET/CT and SPECT/CT

Atlas and Anatomy of PET/CT

Vanessa Murad1, 2  , E. Edmund Kim3, 4, Jin-Chul Paeng1, Camilo Barragan5 and Gi-Jeong Cheon1

Department of Nuclear Medicine, Seoul National University College of Medicine, Seoul, Republic of Korea

Department of Diagnostic Imaging, Fundacion Santa Fe de Bogotá University Hospital, Bogota, Colombia

Department of Radiological Sciences, University of California, Irvine, School of Medicine, Orange, CA, USA

Department of Nuclear Medicine and Department of Molecular Medicine, Graduate School of Convergence Science and Technology, Seoul National University College of Medicine, Seoul, Republic of Korea

Joint Department of Medical Imaging, University Health Network, University of Toronto, Toronto, ON, Canada


PET/CT is a combined system of positron emission tomography (PET) and computed tomography (CT) scanners. PET can detect abnormal metabolic activity in organs or lesions even before they show morphological changes and CT enables precise localization, so co-registration of functional and anatomic information is achieved in the same study, obtained on the same scanner [1]. This technology, available now for at least 10 years, has allowed great advances especially in the field of oncology, and every day it opens more fields to explore in this and other multiple pathologies [2]. Nowadays there is also the possibility of carrying out total body PET studies, which encompasses the entire body within the field of view of the scanner, allowing imaging of all the tissues and organs simultaneously. The increase in geometric coverage of total body PET and multiple adjusted parameters make the whole-body image a very sensitive study with major implications for medical imaging.

PET/CT is currently widely available in the world and many guidelines already recommend it as part of the diagnosis, staging, follow-up, or re-evaluation of various pathologies. As for PET/MR, nonspecific 18F-FDG is the most widely used an available radiotracer for PET/CT studies, and thus many other new tracers are available or under investigation, to offer better possibilities to patients and not only in the field of oncology [2, 3]. Indications for FDG PET/CT are continuously evolving according to the advances that current research allows; however, in oncology it can be useful in various stages of the disease depending on the pathology: initial diagnosis, staging, therapeutic approach, evaluation of response to treatment and recurrence. A great example, and perhaps one of the most frequently used with multiple indications is lymphoma [3, 4]. Other frequent scenarios in which it has a diagnostic utility are the evaluation of a solitary pulmonary nodule, multiple myeloma, and search for a primary tumor of unknown origin [57]. Its usefulness in staging due to the ability to evaluate the whole body, detect lymph node or distant metastasis, and offer some prognostic information can be extended to almost all cancer pathology, but it has been evaluated with better results in melanoma, head and neck, lung, colorectal, gynecological and esophageal cancers among others, as well as in bone and soft tissue sarcomas [3, 811]. Likewise, in some cases such as lung, esophageal, and colorectal cancers, it has shown great utility in radiotherapy planning with excellent results [12, 13]. Response assessment utility depends on the characteristics of the primary tumor and stage, but in lung, esophageal, and colorectal cancers, the results have been promising [10, 13, 14]. Finally, in the evaluation of recurrence, its diagnostic accuracy may also be subject to the characteristics of the primary tumor, but since a large part of the metastases are more aggressive and metabolically active, it represents a good tool for almost all tumors, especially for head and neck, lung, gynecological, and bone and soft tissue tumors. It is important to bear in mind that although it is not indicated for the diagnosis or staging of a series of non-FDG avid tumors (stomach, pancreas, hepatoma, genitourinary tract, ovary, among others), when there is a suspicion of relapse it may play an important role [3, 15, 16].

As in PET/MRI, the availability of multiple novel radiotracers has allowed great advances, especially in neuroendocrine tumors, prostate cancer, and neuro-oncology and degenerative diseases, having the same tracers previously described available for PET/CT studies [17].

In this chapter, we present multiple demonstrative examples of the different uses of FDG and non-FDG PET/CT, with the most relevant anatomical references for each case.


1.1 Head and Neck

1.1.1 Case 1

A 56-year-old female patient with frontal headaches during the last 3 months. Brain 18F-FDG PET/CT was performed for malignancy work-up. Images showed mild and irregular increased activity in the cingulate cortex and corpus callosum, at a lobulated and calcified extra axial mass, and later proved to be a meningioma (WHO grade I). The increased activity in this case may represent an artifact due to the dense and irregular calcification, rather than a definite uptake by the mass (Figs. 1 and 2).

Fig. 1

1. Left superior frontal gyrus

2. Left middle frontal gyrus

3. Calcified meningioma in the corpus callosum

4. Perilesional edema in the posterior left periventricular area

5. Falx cerebri

6. Right corona radiata

7. Right lateral ventricle

8. Superior sagittal sinus

Fig. 2

1. Falx cerebri

2. Left medial frontal gyrus

3. Left caudate nucleus head

4. Perilesional edema in the posterior left periventricular area

5. Right lateral ventricle, anterior horn

6. Right putamen

7. Right cistern of lateral cerebral fossa (insular cistern)

8. Right thalamus

9. Right lateral ventricle, posterior horn

10. Straight sinus

11. Superior sagittal sinus

1.1.2 Case 2

A 65-year-old woman with a history of lung squamous cell carcinoma undergoing chemotherapy, who attended her routine follow-up completely asymptomatic. 18F-FDG PET/CT was performed finding a newly developed focal hypometabolic lesion in the left parietal cortex with peripheral mild, diffuse hypometabolism, which was confirmed to be a metastatic lesion with surrounding edema on contrast MRI (Figs. 3 and 4) [18].

Figs. 3 and 4

1. Right parietalcortex, precentral gyrus

2. Hypometabolic metastasis in left parietal cortex

3. Right frontal cortex, superior frontal gyrus

4. Diffuse hypometabolism in the left parietal cortex and white matter representing perilesional edema

5. Right cingulate gyrus

6. Occipital cortex

7. Left centrum semiovale

8. Right frontal lobe

9. Right frontal skull

10. Lateral ventricles

11. Left parietal lobe

12. Left frontal scalp

13. Head of caudate nucleus

14. Left temporal lobe

15. Right occipital lobe

16. Sella turcica

17. Right auricle

18. Right temporal muscle

19. Frontal sinuses

20. Left sphenoid bone

21. Left mastoid air cells

1.1.3 Case 3

A 17-year-old male patient with persistent headache and obstructive hydrocephalus on brain CT. 18F-FDG PET/CT was performed finding two lesions, one located in the suprasellar region and the other in the pineal region. Both lesions showed very low FDG uptake and heterogeneous density with cystic components and calcifications. Biopsy revealed the diagnosis of bifocal germinoma, which can be found in 2–18% of cases. It remains unclear if this represents synchronous tumors or metastatic disease, but it is known that these patients have a worse prognosis (Fig. 5) [19].

Fig. 5

1. Suprasellar germinoma

2. Pineal germinoma

3. Lacrimal glands with mild increased activity

4. Olfactory cortex

5. Right mastoid air cells

6. Midbrain

7. Torcula Herophili (confluence of the sinuses)

8. Left middle cerebral artery

9. Ethmoid air cells

10. Left thalamus

11. Body of the left lateral ventricle

12. Anterior horn of the right lateral ventricle

13. Third ventricle

14. Posterior limb of the right internal capsule

15. Posterior horn of the right lateral ventricle

16. Frontal sinuses

17. Left eye lens

18. Left eye vitreous chamber

19. Left optic nerve

20. Choroid plexus at the right lateral ventricle

1.1.4 Case 4

A 64-year-old man with occasional headache. Initial brain CT revealed an expansive heterogeneous lesion in the clivus, so 18F-FDG PET/CT was performed to determine its nature. Images showed minimal diffusely increased activity in an expansive, well-defined, lytic lesion in the superior and central aspect of the clivus. These findings favored the diagnosis of a chordoma, which differs from chondrosarcoma because the latter generally presents greater FDG uptake and a chondroid matrix with typical calcifications in rings and arcs (Fig. 6) [20].

Fig. 6

1. Clival chordomas

2. Optic nerves

3. Right zygomatic bone

4. Right temporal lobe

5. Right mastoid air cells

6. Right cerebellum

7. Nasal septum

8. Right nasal bone

9. Right ethmoid sinus

10. Right sphenoid bone

11. Right internal carotid artery

12. Right petrous pyramid

13. Physiologic increased uptake at the visual cortex

14. External occipital protuberance

15. Cerebellum

16. Brainstem

17. Atlantoaxial joint

18. Soft palate

19. Nasal bones

20. Middle nasal concha

21. Hard palate

22. C2, odontoid process (dens)

23. Foramen magnum

24. Clivus

25. Sella turcica/pituitary gland

1.1.5 Case 5

A 65-year-old man with progressive hoarseness. In otolaryngology consultation, physical examination and laryngoscopy revealed a tiny lesion in the right side of the glottis. Biopsy confirmed a squamous cell carcinoma, so 18F-FDG PET/CT scan was requested for staging. Images showed focal increased uptake in the right side of the glottis, at the site of the primary tumor, which represents a metabolic change without an evident anatomical abnormality. No hypermetabolic lymph nodes or distant metastases were found [9] (Figs. 7 and 8).

Figs. 7 and 8

1. Submandibular glands

2. Metabolically active glottis squamous cell carcinoma

3. Hyoid bone

4. Cervical transverse foramen, vertebral artery

5. Cervical vertebral body posterior arch

6. Arytenoid cartilages

7. Cricoid cartilage

8. Pre-epiglottic fat

9. Left pyriform sinus

10. Cervical vertebrae, spinous process

11. Thyroid cartilage

12. Cervical vertebral body

13. Left vocal cord

14. Left splenius capitis muscle

15. Left levator scapula muscle

16. Left trapezius muscle

17. Left parietal lobe

18. Left temporal lobe

19. Sphenoid sinus

20. Right mandible ramus

21. Sternum

22. Left parapharyngeal space

23. Left clavicle

24. Left humerus

25. Occipital lobe

26. Cerebellum

27. Cervical spine

28. Frontal sinus

29. Ethmoid cells

30. Nasopharynx

31. Oropharynx

32. Tongue

33. Epiglottis

34. Glottis

35. Trachea

1.1.6 Case 6

A 45-year-old woman with progressive enlargement of the thyroid gland and occasional pain. Ultrasound and ultrasound-guided biopsy confirmed the diagnosis of diffuse, large B-cell lymphoma, so 18F-FDG PET/CT was performed for staging. Images showed marked increased activity in the diffusely enlarged thyroid gland. No hypermetabolic lymph nodes or distant metastasis were noted (Fig. 9) [21].

Fig. 9

1. Left optic nerve

2. Right thyroid lobe, lymphoma involvement

3. Left thyroid lobe, lymphoma involvement

4. Thyroid isthmus

5. Heart, left ventricular wall uptake

6. Right subclavian vein

7. Right brachiocephalic vein

8. Trachea

9. Normal left axillary lymph nodes

10. Right humeral head

11. Left acromion

12. Right glenoid

13. Left scapular spine

14. Left clavicle

15. Left interpectoral area

16. Posterior cervical fat

17. Left pulmonary apex

1.1.7 Case 7

An 85-year-old man with odynophagia . Physical examination revealed enlargement and ulceration of the right palatine tonsil and biopsy confirmed the diagnosis of a squamous cell carcinoma, so FDG was performed for staging. Images showed focal increased activity in the right palatine tonsil at the primary tumor, as well as two hypermetabolic metastatic lymph nodes in the right upper neck, level II. Note the obliteration of the right parapharyngeal space, which is one of the indirect signs of lesions at this location (Fig. 10) [9].

Fig. 10

1. Metabolically active primary tumor in the right tonsil

2. Metabolically active metastatic lymph nodes in the right neck, level II

3. Mild hypermetabolic lymph nodes in the right lung hilum, inflammatory

4. Right renal pelvis

5. Mandible

6. Right sublingual space

7. Genioglossus muscle

8. Left masseter muscle

9. Left mylohyoid muscle

10. Left parapharyngeal space

11. Left parotid gland

12. Left oblique capitis muscle

13. Left splenius capitis muscle

14. Right mylohyoid muscle

15. Oropharynx

16. Left submandibular gland

17. Left vertebral foramen

18. Spinal canal

1.2 Chest

1.2.1 Case 1

A 25-year-old man with rapid weight loss. Initial studies showed high alpha-fetoprotein (AFP) and a mediastinal mass in the chest X-ray, so 18F-FDG PET/CT was performed on suspicion of a germ cell tumor. Images showed a well-defined, cystic-necrotic anterior mediastinal mass, with a peripheral hypermetabolic solid component, which suggested a more aggressive behavior favoring a non-seminomatous tumor. Posterior biopsy confirmed the diagnosis of a yolk sac tumor (Fig. 11).

Fig. 11

1. Primary tumor with large cystic-necrotic component and hypermetabolic solid peripheral component

2. Right ureter

3. Sternum

4. Spinal canal

5. Descending aorta

6. Left pulmonary artery, upper lobe branch

7. Left scapula

8. Superior vena cava

9. Ascending aorta

10. Main pulmonary artery

11. Left main bronchus

12. Right atrium, superior aspect

13. Esophagus

1.2.2 Case 2

A 43-year-old woman with occasional dyspnea and chest tightness. Chest X-ray and CT were performed, finding a mediastinal mass and considering lymphoma or thymoma as differential diagnoses, so 18F-FDG PET/CT was performed. Images showed an irregular, well-defined anterior mediastinal mass, with an adequate cleavage plane with the vascular structures, with mild homogeneous FDG uptake. With these findings, the diagnosis of low-grade thymoma was suggested and biopsy confirmed a type AB thymoma (Fig. 12) [22].

Fig. 12

1. Anterior mediastinal mass with mild homogeneous FDG uptake, consistent with thymoma type AB

2. Left ventricle

3. Left renal pelvis

4. Right middle ureter

5. Cavo-atrial junction

6. Ascending aorta

7. Descending aorta

8. Left main bronchus

9. Homogeneous cystic lesion in the right thyroid lobe

10. Left thyroid lobe

11. Aortic root

12. Right ventricle

13. Right atrium

14. Left pericardial recess

1.2.3 Case 3

A 50-year-old man with progressive dyspnea and chest pain. Chest X-ray and CT showed an anterior mediastinal mass, so 18F-FDG PET/CT was performed. Images showed a large, irregular, but not infiltrative, mild, metabolically active anterior mediastinal mass with dystrophic calcifications. Extensive pleural invasion with the same mild, diffuse uptake as the primary tumor was observed. The findings suggested a low-grade thymoma and later biopsy confirmed a thymoma type B1 (Fig. 13) [22].

Fig. 13

1. Slight hypermetabolic anterior mediastinal mass corresponding to thymoma type B1

2. Thymoma type B1, left superior aspect with dystrophic calcifications

3. Superior vena cava

4. Common pulmonary artery

5. Extensive left pleural invasion

6. Thymoma type B1, right inferior aspect

7. Left ventricular wall

8. Right main pulmonary artery

9. Right lung lower lobe

10. Left main bronchus

11. Sternum

12. Descending aorta

13. Right internal mammary vessels

14. Pericardial fat

1.2.4 Case 4

A 58-year-old patient with atypical and occasional chest pain who underwent an echocardiogram, finding a poorly defined mediastinal lesion. Contrast CT and 18F-FDG PET/CT revealed a poorly defined infiltrative mediastinal lesion with high and homogeneous FDG uptake, as well as a right inferior pleural seeding. The findings were suspicious of a high-grade thymoma, and postsurgical pathology of the pleural lesion confirmed the diagnosis of a thymoma type B3 (Fig. 14) [22].

Fig. 14

1. Increased activity in the infiltrating mass, consistent with thymoma type B3

2. Metabolically active right lower lobe pleural seeding

3. Gastric antrum physiologic FDG uptake

4. Right upper lobe

5. Ascending aorta

6. Common pulmonary artery

7. Right lower lobe

8. Right main bronchus

9. Descending aorta

10. Left main bronchus

11. Left upper lobe

12. Left ventricle

13. Lower esophagus

14. Right ventricle

15. Right atrium

16. Left lower lobe

1.2.5 Case 5

A 58-year-old female patient with a history of diffuse, large B-cell lymphoma with lymph node involvement, treated with chemotherapy achieving complete metabolic response. In the last 18F-FDG PET/CT checkup, multiple new hypermetabolic mediastinal lymph nodes were noted, with a distribution in bilateral hilar, subcarinal, and right paratracheal areas (lambda sign). Also, diffusely increased activity was detected in the soft tissues of the lower lumbar region and left gluteal region. Given the suspicion of lymphoma recurrence, biopsy of both the lymph nodes and the soft tissue lesions was performed, where chronic granulomatous changes consistent with sarcoidosis were reported (Fig. 15).

Fig. 15

1. Metabolically active mediastinal lymph nodes, lambda sign

2. Ascending aorta

3. Right hilar lymph nodes, level 10R

4. Right main bronchus

5. Subcarinal lymph nodes, level 7

6. Main pulmonary artery

7. Left hilar lymph nodes, 10L

8. Esophagus

9. Descending aorta

10. Left main bronchus

11. Right ureter, distal third

12. Gluteus medius muscles

13. Increased activity at left iliac bone involvement

14. Left iliopsoas muscle

15. Left iliac wing

16. Left sacroiliac joint

17. Increased activity at left gluteal soft tissue involvement

18. Right gluteus maximus muscle

19. Sacrum

20. Left acetabular roof

21. Metabolically active intergluteal lymph node

1.2.6 Case 6

A 51-year-old man with dyspnea and chest pain, with normal chest X-ray. Suspecting pulmonary embolism (PE) , chest CT angiography was requested, finding an extensive filling defect in the pulmonary trunk, the entire right pulmonary artery and the branch for the superior lobe, as well as in the proximal left pulmonary artery. However, the filling defect was irregular and showed enhancement, indicating that it was more likely a soft tissue lesion or a tumor thrombus, so 18F-FDG PET/CT was performed. Images showed marked increased activity in the irregular intravascular lesion without other findings. A primary angiosarcoma of the pulmonary artery was suggested as the diagnosis, which was later confirmed with biopsy (Fig. 16) [23].

Fig. 16

1. Metabolically active tumor in the pulmonary artery

2. Angiosarcoma involvement at the main pulmonary artery

3. Angiosarcoma involvement at the right pulmonary artery

4. Angiosarcoma involvement at the right upper lobe artery

5. Ascending aorta

6. Left atrium superior aspect

7. Descending aorta

8. Right interlobar artery

9. Superior vena cava

10. Left pulmonary artery

11. Right main bronchus

12. Sternum

13. Spinal canal

14. Left rib posterior arc

15. Left main bronchus

16. Left upper lobe pulmonary artery

17. Thoracic vertebra left transverse process

18. Esophagus

19. Right costovertebral joint

1.2.7 Case 7

A 28-year-old woman with occasional chest pain. Chest X-ray was performed finding a mediastinal mass, so 18F-FDG PET/CT was ordered for further evaluation. Initial images (superior) showed intense FDG uptake in a bulky anterior mediastinal mass, as well as metabolically active enlarged lymph nodes at the lower neck and right cardiophrenic and left retroperitoneal areas. The diagnosis of primary mediastinal B-cell lymphoma was confirmed and first-line chemotherapy was started. Two cycles later, in the follow-up 18F-FDG PET/CT, complete metabolic resolution of the previously visualized lesions was observed. This unique and rare subtype of non-Hodgkin lymphoma occurs in only 2–3% of cases (Fig. 17) [24].

Fig. 17

1. Metabolically active bulky anterior mediastinal mass

2. Hypermetabolic enlarged lymph nodes in the bilateral lower neck

3. Focal increased activity in right cardiophrenic lymph node

4. Focal increased activity in left retroperitoneal lymph node

5. Focal increased activity in right hilar lymph node

6. Thoracic vertebral body spinous process

7. Thoracic vertebral body left transverse process

8. Left scapula

9. Right ventricle

10. Right costovertebral junction

11. Descending aorta

12. Left ventricle

13. Posttreatment residual calcification

14. Residual soft tissue lesion in the anterior mediastinum with no definite FDG uptake (Deauville 1)

15. Sternum

16. Left breast tissue

17. Left major pectoralis muscle

18. Left minor pectoralis muscle

19. Left axillary fossa

20. Left rib, lateral arc

21. Carina

22. Superior vena cava

23. Esophagus

1.2.8 Case 8

A 54-year-old woman with diagnosis of infiltrating ductal carcinoma of the left breast and suspected axillary lymph node metastases. As part of staging, 18F-FDG PET/CT was performed. Images showed diffuse, increased activity in the left breast, predominantly toward the lower outer quadrant, where the primary lesion was confirmed. Furthermore, multiple metabolically active lymph node metastases were observed at all left axillary levels, supraclavicular region, and mediastinum. In the normal right breast parenchyma, diffuse FDG uptake is perceived, which represents normal physiologic activity frequently seen in premenopausal women (Figs. 18 and 19) [25].

Fig. 18

1. Hypermetabolic diffuse infiltrative left breast cancer

2. Multiple hypermetabolic lymph node metastasis

3. Normal right breast tissue with mild, diffuse FDG uptake

4. Right internal mammary chain, normal

5. Sternum

6. Right atrium

7. Left atrium

8. Common pulmonary artery

9. Hypermetabolic infracarinal lymph node (level 7)

10. Ascending aorta

11. Right hilum (11R metastasis)

12. Lower esophagus

13. Left hypermetabolic lymph node (level L11)

14. Left main bronchus

15. Left scapula

Fig. 19

1. Bilateral superior mediastinal lymph nodes (level 1–2)

2. Right lung, upper lobe

3. Level III hypermetabolic lymph node

4. Level II hypermetabolic lymph nodes

5. Level I hypermetabolic lymph node

6. Left major pectoralis muscle

7. Left minor pectoralis muscle

8. Interpectoral lymph node (Rotter lymph node)

9. Right clavicle

10. Left lung, upper lobe

11. Trachea

12. Right thyroid lobe with mild, diffuse uptake

13. Hypermetabolic left supraclavicular lymph nodes

14. Left deltoid muscle

15. Left trapezius muscle

1.2.9 Case 9

A 48-year-old woman with progressive pain, redness, and hardening of the left breast, associated with bloody nipple discharge. Ultrasound and biopsy were performed confirming the diagnosis of an inflammatory carcinoma and 18F-FDG PET/CT was requested for staging. Images showed a metabolically active multifocal left breast cancer with increased activity at marked skin thickening. Multiple hypermetabolic metastatic lymph nodes were also observed, predominantly in the axillary level I, as well as same-side interpectoral area and internal mammary chain (Fig. 20) [25].

Fig. 20

1. Metabolically active multifocal left breast cancer

2. Multiple hypermetabolic metastatic lymph nodes

3. Left renal pelvis

4. Right ureter

5. Left adnexal physiologic activity

6. Normal right breast tissue

7. Increased activity at skin thickening in the left breast

8. Mediastinal vessels

9. Left internal mammary lymph node metastasis

10. Minor pectoralis muscle

11. Metastatic left axillary lymph nodes, level I

12. Left scapula

13. Right axillary fossa

14. Trachea

15. Right subclavian vessels

16. Right lung apex

17. Left first rib, anterior arc

18. Interpectoral lymph node (Rotter) metastasis

19. Left major pectoralis muscle

20. Left second rib, posterior arc

1.2.10 Case 10

An 80-year-old male patient with history of scalp angiosarcoma, treated with surgery and chemotherapy. Follow-up 18F-FDG PET/CT was performed 8 months after surgery and showed multiple new lesions, including a small left upper lobe pneumothorax chamber, increased activity at a right middle lobe ground glass opacity, and multiple randomly distributed, thin-walled cystic lesions, some with peripheral FDG uptake. Hypermetabolic lymph nodes were also noted in the subcarinal and bilateral hilar areas. Ultrasound-guided endobronchial biopsy revealed the suspected diagnosis: angiosarcoma metastasis (Fig. 21) [26].

Fig. 21

1. Metabolically active right hilar lymph nodes

2. Diffusely increased activity in ground-glass opacities at the right middle lobe

3. Left renal pelvis

4. Thin-walled cystic metastasis with peripheral uptake at the right upper lobe

5. Hypermetabolic subcarinal lymph nodes

6. Right lower lobe with multiple thin-walled cystic metastasis

7. Small left upper lobe pneumothorax chamber

8. Hypermetabolic left hilar lymph node

9. Left lower lobe

10. Diffusely increased uptake in the left ventricular wall

11. Thin-walled cystic metastasis with peripheral uptake at the left lower lobe

1.2.11 Case 11

A 43-year-old male patient, currently smoker, who presented with persistent productive cough with occasional drops of blood. 18F-FDG PET/CT was performed, finding multiple metabolically active solid nodules with random distribution in both lungs, with two dominant lesions at the right lung, one of them with central cavitation. Ultrasound-guided endobronchial biopsy confirmed the diagnosis of primary pulmonary melanoma at the right upper lobe, with multiple bilateral metastases. Additionally, a metastatic mediastinal lymph node conglomerate with necrotic components was found involving levels 7, 10R, and 11R, as well as a right neck level II metabolically active lymph node (Figs. 22 and 23) [27].

Figs. 22 and 23

1. Right upper lobe hypermetabolic cavitated nodule

2. Mediastinal lymph node conglomerate with uneven uptake due to necrosis

3. Trachea

4. Aortic arch

5. Right upper lobe hypermetabolic solid nodule

6. Left upper lobe metastatic ground glass nodule

7. Solid metastases

8. Right upper lobe

9. Left upper lobe

10. Right main bronchus

11. Carina

12. Descending aorta

13. Left bronchus

14. Right middle lobe

15. Anterior junction line of the pleura

16. Left lower lobe, lingula

17. Diaphragm, liver dome

18. Right ventricle

19. Left ventricle

20. Right lower lobe

21. Left lower lobe

22. Right neck level II lymph node metastasis

1.2.12 Case 12

A 74-year-old woman with significant weight loss. Chest X-ray showed a mediastinal mass, so 18F-FDG PET/CT was performed. Images revealed a high metabolically active left hilar mass with multiple mediastinal and lower neck metastatic lymph nodes, as well as a retroperitoneal lymph node. The diagnosis of a primary lung cancer was suggested, but transbronchial biopsy confirmed a diffuse, large B-cell lymphoma. Findings that favor the diagnosis of lymphoma include the presence of a bulky mass with bulky lymph nodes, which surrounds or encases the bronchial and vascular structures, without compressing or invading them. Also, the presence of lymph nodes in other locations can give a clue, although there is no definitive finding to differentiate them from metastasis of a primary lung tumor (Fig. 24) [28].

Fig. 24

1. Lymphoma involvement at lower cervical lymph nodes

2. Metabolically active left hilar mass, consistent with diffuse large B-cell lymphoma

3. Superior vena cava

4. Carina

5. Tip of the right scapula

6. Lymphoma involvement at upper aortocaval lymph node

7. Right breast fibroglandular tissue

8. Sternum

9. Lymphoma involvement at subcarinal lymph nodes

10. Lymphoma involvement at right hilar lymph nodes

11. Thoracic vertebral body

12. Lymphoma involvement at prevascular lymph nodes

13. Azygos vein

14. Ascending aorta

15. Esophagus

16. Descending aorta

17. Right main pulmonary artery

18. Common pulmonary artery

19. Left main bronchus

20. Spinal cord

1.2.13 Case 13

A 75-year-old female patient with history of breast cancer and recent diagnosis of small cell lung cancer, in treatment with immunotherapy (atezolizumab). Follow-up 18F-FDG PET/CT showed increased size of metabolically active primary tumor in the left upper lobe, with a peripheral area of necrosis, as well as increased activity in two lesions that were previously not so evident, one in the left diaphragmatic crus and other in the right perirenal area. At this time, the possibility of a pseudo-progression due to the ongoing treatment was considered, which was confirmed with the following follow-up, where metabolic response of all the described lesions was observed (Fig. 25) [29].

Fig. 25

1. Metabolically active primary tumor in the left upper lobe. Note the posterior necrotic component of the mass in the follow-up study

2. Right main bronchus

3. Left main bronchus

4. Small amount of left pleural effusion

5. Left mastectomy post-op changes

6. Increased activity at nodular lesion in the right perirenal space

7. Thoracic vertebral body osteophyte

8. Left pulmonary hilum

9. Ascending colon

10. Right kidney, inferior pole

11. Aortocaval space

12. Right psoas muscle

13. Left ureter

14. Left perirenal fat

15. Descending colon

16. T11 right costovertebral junction

17. Spinal canal

18. Right diaphragmatic crus

19. Caudate lobe

20. Left hepatic lobe

21. Increased activity at nodular lesion in the left diaphragmatic crus

1.2.14 Case 14

A 59-year-old woman with a history of breast cancer 25 years ago. She attended due to progressive dyspnea and chest radiograph showed diffuse opacity of the left lung, so 18F-FDG PET/CT was performed. Images showed marked increased activity in diffuse nodular pleural thickening of the left lung, with involvement of the major fissure; there was no significant pleural effusion or mediastinal lymph nodes. Pleural mesothelioma was initially suspected, but biopsy confirmed the diagnosis of pleural metastases from breast carcinoma. Although it is not the most frequent site of metastasis, the pleura can be the only manifestation of recurrent disease in up to 40% of cases (Fig. 26) [30].

Fig. 26

1. Marked increased activity at diffuse left pleural nodular thickening

2. Increased activity at left major fissure involvement

3. Increased activity at the deep left costophrenic angle involvement

4. Sternum

5. Ascending aorta

6. Right main pulmonary artery

7. Right scapula

8. Pulmonary trunk

9. Left main bronchus

10. Right pulmonary hilum

11. Gastroesophageal junction

12. Right hepatic lobe

13. Abdominal aorta

14. Ascending colon

15. Trachea

16. Aortic arch

1.2.15 Case 15

A 54-year-old woman with dyspnea and fatigue for several months. Chest X-ray was performed, finding bilateral pleural effusion and cardiomegaly. Given the suspicion of pulmonary embolism, contrast-enhanced CT was performed, finding a soft tissue mass involving the right ventricle, superior vena cava, and innominate veins, as well as mild pericardial effusion. 18F-FDG PET/CT was performed for whole body evaluation, observing moderate, diffuse, increased activity in the soft tissue lesion described in tomography. Final diagnosis was consistent with a superior vena cava angiosarcoma (Fig. 27) [23].

Fig. 27

1. Hypermetabolic angiosarcoma, right ventricle component

2. Physiologic uptake in the left ventricle wall

3. Trachea

4. Pericardial effusion

5. Bilateral pleural effusion

6. Left ventricle

7. Esophagus

8. Hypermetabolic angiosarcoma, superior vena cava component

9. Sternum

10. Sphenoid sinus

11. Nasopharynx

12. Oropharynx

1.2.16 Case 16

A 34-year-old male patient with progressive odynophagia and night sweats. 18F-FDG PET/CT was performed finding a metabolically active mass in the oropharynx, consistent with biopsy-confirmed diffuse, large B-cell lymphoma; no other hypermetabolic lesion suggestive of lymphoma involvement was found. However, two incidental cardiac findings were found: (1) diffuse increase in FDG uptake at the right ventricular wall, secondary to pulmonary hypertension and (2) focal FDG uptake at the upper portion of the interventricular septum, protruding into the left ventricle. The last finding corresponds to an asymmetric or isolated septal hypertrophy, also known as interventricular septal bulge (Fig. 28) [31].

Fig. 28

1. Metabolically active oropharyngeal lymphoma

2. Cerebellum

3. Diffuse FDG uptake in the right ventricular wall

4. Diffuse FDG uptake in the left ventricular wall

5. Right atrium

6. Descending aorta

7. Thoracic vertebral body

8. Spinal cord

9. Right costovertebral junction

10. Vertebral right transverse process

11. Vertebral spinous process

12. Right costal cartilage

13. Right ventricle papillary muscle

14. Left rib, lateral arc

15. Left rib, posterior arc

16. Asymmetric or isolated septal hypertrophy, also known as interventricular septal bulge

1.2.17 Case 17

An 18-year-old man with diagnosis of Hodgkin lymphoma with inguinal lymph nodes involvement, undergoing treatment with first-line chemotherapy. After the second cycle, follow-up 18F-FDG PET/CT was performed, where complete resolution of the previously visualized lymph nodes was observed. However, as a new finding, increased activity was found at the aortic root, consistent with inflammatory changes (aortitis), more likely related to the established treatment (Fig. 29) [32].

Fig. 29

1. Diffusely increased activity at the aortic root

2. Increased activity at the vocal cords

3. Increased activity at the distal esophagus, probable esophagitis

4. Renal pelvis

5. Right middle ureter

6. Right ventricle

7. Left atrium

8. Left pulmonary vein

9. Spinal canal

10. Right atrium

11. Right pulmonary vein

12. Right costovertebral junction

13. Esophagus

14. Descending aorta

1.2.18 Case 18

A 32-year-old man diagnosed with Hodgkin lymphoma with nodal involvement. 18F-FDG PET/CT was performed for end-of-therapy follow-up, where complete resolution of previously identified lymph nodes was found, consistent with metabolic complete response. However, increased activity was found in the bilateral neck, supraclavicular fossae, and thoracic paravertebral areas, corresponding in the CT to fat with no underlying lesion. This finding represents metabolically active adipose tissue or brown fat and is a common finding specially related to cold temperatures (Fig. 30) [33].

Fig. 30

1. Brown adipose tissue in typical locations: neck, supraclavicular fossa and paravertebral space

2. Right double collecting system

3. Right first rib

4. Trachea

5. Left clavicle

6. Left humeral head

7. Left glenoid

8. Left scapula

9. Thyroid gland, left lobe

10. Left sternohyoid muscle

11. Left pectoralis major muscle

12. Left subclavian vessels

13. Left trapezius muscle

14. Left paraspinal muscles

15. Right third rib posterior arc

16. Liver

17. Right kidney

18. Stomach

19. Spleen

20. Descending colon

21. Mastoid air cells

22. Nuchal ligament

23. Parotid gland

24. Mandible ramus

25. Pulmonary hilum

1.2.19 Case 19

A 71-year-old man with progressive fatigue, weight loss, and dyspnea, as well as fever in the last 3 weeks. Chest X-ray and CT did not show any remarkable findings, so 18F-FDG PET/CT was performed to rule out occult malignancy. Images showed multiple hypermetabolic mediastinal lymph nodes in paratracheal and bilateral hilar areas, as well as markedly increased activity in the enlarged spleen. Widespread FDG uptake was noted in both lungs without any CT abnormality. Transbronchial lymph node biopsy confirmed the diagnosis of diffuse, large B-cell lymphoma. Although the initial bronchoalveolar lavage only showed increased alveolar macrophages, without evidence of abnormal lymphocytes, in the follow-up study all pulmonary findings disappeared as did the lymph nodes and splenomegaly. There are some cases with similar lung findings reported in the literature, where the histopathologic diagnosis of intravascular large B-cell lymphoma has been confirmed with the presence of large atypical lymphocytes in the lumina of the capillary vessels, so in this case, these findings and their evolution most likely represent lymphoma involvement (Fig. 31) [34].

Fig. 31

1. Hypermetabolic right paratracheal lymph nodes

2. Diffusely increased activity at bilateral lungs without discernible CT abnormality

3. Metabolically active splenomegaly

4. Hypermetabolic lymph nodes in prevascular area

5. Trachea

6. Esophagus

7. Thoracic vertebral body

8. Left costovertebral junction

9. Left rib posterior arc

10. Anterior junction line

11. Right main bronchus

12. Right lower lobe

13. Left main bronchus

14. Left lower lobe

15. Left hepatic lobe

16. Right hepatic lobe

17. Stomach

1.2.20 Case 20

A 62-year-old woman with a history of Takayasu arteritis, who consulted for acute thoracoabdominal pain. Other possible causes of pain were ruled out, and 18F-FDG PET/CT was performed to assess disease activity and thus define treatment. Images showed generalized increased activity in the walls of the thoracoabdominal aorta, with involvement of the main cervical trunks, the iliac bifurcation, and the proximal iliac arteries. These findings indicate an active acute phase of the disease. No areas of stenosis or aneurysmal dilatation were observed (Fig. 32) [35].

Fig. 32

1. Ascending aorta

2. Brachiocephalic trunk

3. Left common carotid artery

4. Aortic arch

5. Descending aorta

6. Abdominal aorta

7. Iliac bifurcation

8. Common iliac arteries

9. Main pulmonary artery

10. Right pulmonary hilum

11. Sternum

12. Anterior junction line

13. Left atrium

14. Thoracic vertebral body

15. Spinal canal

16. Right costovertebral joint

17. Right renal pelvis

18. Left kidney

19. Right perirenal space

20. Ascending colon

21. Proximal duodenum

22. Stomach

23. Descending colon

24. Left psoas muscle

25. Left paraspinal muscles (multifidus and erector spinae)

1.2.21 Case 21

A 52-year-old male patient with a known diagnosis of Langerhans cell histiocytosis (LCH). After almost 2 years asymptomatic, he presented with lower back pain, so imaging studies including 18F-FDG PET/CT were performed. Images showed diffusely increased activity in a permetative and aggressive lytic lesion involving the left iliac bone and sacral ala, as well as a smaller lesion with same characteristics in the right iliac bone; both lesions corresponded to LCH involvement. Additionally, minimal diffuse increased uptake was observed in both lungs, with multiple small irregular cystic lesions and septal thickening, with findings also corresponding to LCH involvement (Fig. 33).

Fig. 33

1. LCH involvement at the left iliac bone and sacral ala

2. LCH involvement at the right iliac bone

3. Prostatic urethra

4. Testes

5. Right main bronchus

6. Anterior junction line

7. Ascending aorta

8. Left pulmonary hilum

9. Left main bronchus

10. Trachea

11. Right lung apex

12. Horizontal lung fissure

13. Right middle lobe

14. Oblique lung fissure

15. Right lower lobe

16. Left ventricle

17. Left diaphragmatic cupola

18. Sigmoid colon

19. Right iliac wing

20. Right iliac tuberosity

21. Sacral ala

22. Abdominis rectus muscles

23. Right anterior superior iliac spine

24. Right iliopsoas complex

25. Right sacroiliac joint

1.3 Abdomen and Pelvis

1.3.1 Case 1

A 73-year-old man with a history of occasional dysphagia and weight loss. Upper digestive tract endoscopy showed suspicious findings of malignancy, so 18F-FDG PET/CT was performed. Images showed focal increased activity at the distal third of the esophagus in a concentric solid mass, which was later confirmed to correspond to a squamous cell carcinoma. No abnormal lymph nodes or distant metastasis were noted (Fig. 34) [14, 36].

Fig. 34

1. Metabolically active esophageal squamous cell carcinoma

2. Right atrium

3. Left atrium

4. Ascending aorta

5. Descending aorta

6. Aortic knob

7. Left main bronchus

8. Fibrotic changes at the right lung apex

9. Liver dome

10. Gastric fundus

11. Sphenoid sinus

12. Nasopharynx

13. Oropharynx

14. Pharynx

15. Trachea

16. Aortic arch

17. Clivus

18. Right main bronchus

19. Pulmonary artery

1.3.2 Case 2

A 26-year-old female patient with occasional chest pain and reflux. Chest X-ray showed a mediastinal mass, so 18F-FDG PET/CT was performed, finding markedly increased activity in a prominent wall-based mass at the distal esophagus, with exophytic growth and no lumen obstruction or mucosal involvement. The diagnosis of a gastrointestinal stromal tumor (GIST) was considered as the first possibility, which was later confirmed with biopsy (Fig. 35) [36].

Fig. 35

1. Large metabolically active mass in the wall of the distal esophagus

2. Optic nerves

3. Right nipple

4. Right renal pelvis

5. Left ventricle papillary muscle

6. Right ventricle

7. Left ventricle

8. Esophageal lumen

9. Descending aorta

10. Interventricular septum

11. Superior vena cava

12. Left T9 costovertebral junction

1.3.3 Case 3

A 49-year-old man with chronic upper abdominal pain and weight loss. Endoscopic evaluation and biopsy were performed, finding an advanced gastric adenocarcinoma, so 18F-FDG PET/CT was performed for staging. Images showed increased metabolic activity in the gastric fundus and body at irregular wall thickening, consistent with the primary tumor. Metabolically active enlarged lymph nodes at the gastro-hepatic and right retrocrural areas were also noted (Figs. 36 and 37) [16].

Figs. 36 and 37

1. Metabolically active gastric wall thickening: primary gastric adenocarcinoma

2. Hypermetabolic lymph node metastasis at the gastro-hepatic ligament

3. Left hepatic lobe

4. Right hepatic lobe

5. Inferior vena cava

6. Spleen

7. Gallbladder

8. Hepato-duodenal ligament

9. Gastro-splenic ligament

10. Right retrocrural lymph node metastasis

11. Pancreatic tail

12. Left adrenal gland

1.3.4 Case 4

A 54-year-old male patient with weight loss and night sweats during the last 2 months. 18F-FDG PET/CT was performed on suspicion of malignancy, where a bulky metabolically active mass was found in the stomach, as well as multiple prominent hypermetabolic retroperitoneal lymph nodes. With these findings, a lymphoma was suggested, and the subsequent biopsy confirmed the diagnosis: diffuse, large B-cell lymphoma (Fig. 38) [37].

Fig. 38

1. Metabolically active bulky stomach mass

2. Falciform ligament

3. Gallbladder

4. Inferior vena cava

5. Left kidney

6. Gastro-hepatic ligament

7. Hepatic flexure of the colon

8. Spleen

9. Right kidney

10. Hypermetabolic aortocaval lymph nodes

11. Hypermetabolic preaortic lymph nodes

12. Hypermetabolic left paraaortic lymph nodes

13. Pancreatic body

14. Abdominal aorta

1.3.5 Case 5

A 79-year-old woman with acute abdominal pain and vomiting. Contrast-enhanced CT was performed, finding a partial low-grade bowel obstruction with transition zone at the distal ileum. After managing the acute condition, 18F-FDG PET/CT was performed, finding a metabolically active concentric mass at the distal ileum with lumen reduction, without adjacent mesenteric fat stranding or other findings. Surgical resection was performed, confirming a primary large B-cell lymphoma (Fig. 39) [37].

Fig. 39

1. Hypermetabolic concentric mass in the distal ileum

2. Urinary bladder

3. Right femoral head

4. Right iliac wing

5. Sacrum

6. Iliac bifurcation

7. Left acetabulum

8. Left femoral shaft

9. Right gluteus medius muscle

10. Right external iliac vessels

11. Rectum

12. Left piriformis muscle

13. Left gluteus Maximus muscle

14. Ascending colon

15. Right psoas muscle

16. Small bowel loops

17. Left levator ani muscle

18. Left femoral artery

1.3.6 Case 6

A 38-year-old man who attended an annual checkup completely asymptomatic. Colonoscopy and biopsy revealed a colon adenocarcinoma. 18F-FDG PET/CT was performed for staging, finding a focal increased activity in the distal transverse colon corresponding to the primary tumor, as well as a metabolically active mesenteric lymph node metastasis. No distant metastases were noted (Fig. 40) [13].

Fig. 40

1. Metabolically active distal transverse colon adenocarcinoma

2. Metastatic mesenteric lymph node

3. Second portion of duodenum

4. Right adrenal gland

5. Right diaphragmatic crus

6. Spleen

7. Transverse colon

8. Pancreatic body

9. Pancreatic tail

10. Pancreatic head, uncinate process

11. Inferior vena cava

12. Proximal small bowel loops

13. Accessory spleen

1.3.7 Case 7

A 52-year-old woman with a history of constipation and occasional rectal bleeding. 18F-FDG PET/CT was performed to rule out malignancy. Images showed focal increased activity at the sigmoid colon suggesting a polypoid lesion. Colonoscopy and biopsy were performed confirming the diagnosis of sigmoid colon adenocarcinoma. No abnormal hypermetabolic lymph nodes or metastasis were detected (Fig. 41) [13].

Fig. 41

1. Metabolically active sigmoid colon adenocarcinoma

2. Right acetabulum anterior wall

3. Right femoral head

4. Right acetabulum posterior wall

5. Coccygeal vertebral body

6. Subcutaneous fat, anterior abdominopelvic wall

7. Right iliacus muscle

8. Right gluteus medius muscle

9. Right gluteus maximus muscle

10. Mesenteric fat, normal appearance

11. Small bowel loops

12. Descending colon loops

13. Sacrum

14. Right sacral ala

15. Right sacroiliac joint

16. Left paraspinal muscles

17. Left piriformis muscle

1.3.8 Case 8

A 60-year-old man with a history of occasional rectal bleeding worsened in the last 2 weeks. Clinical examination and rectoscopy were performed and confirmed the presence of a mass, so 18F-FDG PET/CT was performed. Images showed a focal increased activity in the lower rectum at the primary tumor site, with no other hypermetabolic lesions suggesting metastasis. Final biopsy confirmed an adenocarcinoma (Fig. 42) [13].

Fig. 42

1. Metabolically active rectal adenocarcinoma

2. Right obturator internus muscle, posterior aspect

3. Prevesical space

4. Prostate gland with dystrophic calcifications

5. Rectum, thickened

6. Right levator ani muscle, puborectalis

7. Left obturator internus muscle, medial aspect

8. Urinary bladder

9. Levator ani muscles, pubococcygeus

10. Seminal vesicles

11. Perirectal fat

12. Coccyx

13. External iliac vessels

14. Perivesical fat

1.3.9 Case 9

A 71-year-old man with a history of ascending colon adenocarcinoma 2 years ago, treated with laparoscopic right hemicolectomy and chemotherapy. He attended due to nodular feeling at the umbilical port scar where ultrasound showed a suspicious mass, so 18F-FDG PET/CT was performed. Images showed a metabolically active spiculated lesion involving the subcutaneous tissue and both rectus abdominis muscles. Biopsy confirmed the presence of metastatic adenocarcinoma, probably secondary to a seeding during prior surgery (Fig. 43) [38].

Fig. 43

1. Hypermetabolic recurred colon cancer in the umbilical port scar

2. Left rectus abdominis muscle

3. Left transversus abdominis muscle

4. Left internal oblique muscle

5. Left external oblique muscle

6. Left psoas muscle

7. Left quadratus lumborum muscle

8. Left erector spinatus muscle

9. Small bowel mesentery

10. Descending colon

11. Small bowel loops

12. Left lumbar neural foramen

13. Abdominal aorta

14. Inferior vena cava

15. Lumbar vertebral body

16. Right vertebral lamina

17. Spinous process

18. Subcutaneous fat, left abdominal wall

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Nov 6, 2022 | Posted by in MAGNETIC RESONANCE IMAGING | Comments Off on and Anatomy of PET/CT

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