Bladder Carcinoma



Bladder Carcinoma


Todd M. Blodgett, MD

Alex Ryan, MD

Omar Almusa, MD









Axial graphic demonstrates a focal mass arising from the posterior aspect of the bladder near the left ureterovesical junction image.






Axial fused PET/CT in a patient scanned in the prone position shows a focal area of activity image, compatible with known bladder cancer.


TERMINOLOGY


Abbreviations and Synonyms



  • Bladder carcinoma, urothelial carcinoma, transitional cell carcinoma (TCC)


Definitions



  • Malignancy of the urinary bladder


IMAGING FINDINGS


General Features



  • Best diagnostic clue



    • PET/CT: Focal increased FDG activity in primary tumor, ± in regional and distant lymph nodes, lung, liver, bone


    • CT: Enhancing focal/asymmetric mass in the urinary bladder


  • Location



    • Usually arises in the bladder wall


    • Can be multifocal


    • Local invasion



      • Detrusor muscle, prostate, uterus, vagina, seminal vesicles, rectum


    • Lymphatic spread (30% of tumors that only involve bladder wall; 60% of those with extravesicular invasion)



      • Regional (pelvic) lymph nodes (LN)


      • Distant LN


    • Hematogenous spread



      • Lung > > liver, bone


    • Recurrences of superficial bladder cancer remain confined to bladder wall in 70-80% of patients



      • Remaining 20-30% may become muscle-invasive and lead to metastatic disease


    • Common metastatic sites include pelvic and retroperitoneal lymph nodes, lungs, liver, and bones


  • Size: Varies from undetectable on CT to large enhancing mass


  • Morphology



    • Superficial: Most common representing 70-80%



      • Confined to mucosa and lamina propria


      • Project into bladder lumen (papillary)


      • Usually low grade


    • Invasive: Less common, representing 20-30%



      • Detrusor muscle involvement



      • Solid, more infiltrating


      • Usually high grade


Imaging Recommendations



  • Best imaging tool



    • Initial workup: Cystoscopy and biopsy; CT or MR for evaluation of primary tumor and LN metastases



      • CT: Reported accuracy in detecting LN involvement 70-90% with false negative rates 25-40%


      • MR: 73-98% reported accuracy for determining nodal metastases


    • PET/CT



      • Utility mostly for pre-operative staging, distinguishing post-surgical change from recurrence


      • Minimally useful for evaluation of primary tumor, usually obscured by excretory FDG


    • Bone scan: Helpful if there is clinical suspicion of bone metastases


    • CT/MR tend to overestimate degree of extension through bladder wall but underestimate presence of pelvic lymph node metastases


  • Protocol advice



    • PET/CT: 10-15 mCi (370-555 MBq) F18-FDG IV, start imaging at pelvis to avoid FDG filling bladder


    • PET/CT: Excreted FDG in urinary bladder can mask pelvic pathology



      • Techniques include Immediate post-void imaging, retrograde bladder irrigation with normal saline, IV Lasix administration with parenteral hydration


      • Prone positioning may be useful for visualization of posteriorly located lesions


    • Urinary excretion of FDG leads to pooled activity in bladder, making evaluation of bladder wall lesions difficult to impossible with standard protocol



      • Furosemide injected at least 2 hours after radiotracer injection provides excellent urinary radiotracer washout, reducing bladder activity to background levels


      • Oral hydration aids in diuresis


      • Full bladder is required to avoid artifactual thickening of the walls


      • Protocol not satisfactory in patients with cystectomy because urinary diversions show higher residual activities, but recurrence is extremely rare in bladder diversion walls


CT Findings



  • CT findings of primary usually nonspecific (diagnosis often based on biopsy performed during cystoscopy)



    • Focal or diffuse bladder wall thickening


    • Mass projecting into bladder ± enhancement


  • Occasionally calcifications


  • Hydronephrosis 2° to tumor near vesicoureteric junction


  • Extravesicular extension: Nodules, irregularity of outer bladder wall, stranding of perivesicular fat


  • T status of tumor most often determined by biopsy


  • Causes of circumferential bladder thickening that can mimic bladder cancer include



    • Previous biopsy, inflammation, radiotherapy, systemic chemotherapy, and intravesical agents like Bacille Calmette-Guérin (BCG)


  • Sessile or pedunculated soft tissue mass projecting into the lumen; similar density to bladder wall


  • ± Enlarged (> 10 mm) metastatic lymph nodes; extravesical tumor extension


  • Fine punctate calcifications with tumor; may suggest mucinous adenocarcinoma


  • Ring pattern of calcification; may suggest pheochromocytoma


  • Inability to distinguish tumors from bladder wall hypertrophy, local inflammation, and fibrosis


  • Unable to differentiate Ta-T3a, invasion of dome/base of bladder or local organ (due to partial volume effect), nonenlarged lymph nodes


  • Also consider urachal adenocarcinoma



    • Midline abdominal mass ± calcification


    • Solitary lobulated tumor arising from dome of bladder on ventral surface



MR Findings



  • T1WI: Isointense to muscle


  • T2WI: Hyperintense to muscle


  • Superior to CT for assessing deep muscle involvement, invasion of adjacent organs


Nuclear Medicine Findings



  • Focal increased FDG activity in primary tumor, regional and distant LN, lung, liver, bone



    • Bladder cancer may have variable uptake of FDG


    • Baseline PET/CT useful for confirmation of FDG avidity


    • Max SUV may range from 5-10 in typical hypermetabolic bladder lesions


  • Primary tumor may be masked by excreted FDG in urine



    • FDG is not resorbed as glucose and is excreted in the urine


    • With delayed imaging, ratio of tumor:bladder FDG uptake was 13:1 in one study


  • False positives: Bladder diverticula and urinary leak



    • CT portion of PET/CT essential for ruling out such pitfalls


    • CT also useful for precise separation of uptake foci in the bladder wall vs. lymph nodes adjacent to bladder


    • One study showed 3 month period post-resection was sufficient to heal inflammatory reactions and reduce false positives


  • C-11-choline PET/CT radiotracer does not collect in urinary tract, but its value for lesion staging has not been shown superior to conventional methods


  • Bone scan: Bone metastases classically appear as multiple, scattered foci of increased activity, axial > appendicular skeleton


DIFFERENTIAL DIAGNOSIS


Cystitis



  • Usually more diffuse thickening of the bladder wall


  • Chronic urinary tract infection, fungus


  • Radiation- or chemotherapy-induced


  • Hemorrhagic cystitis


Hematoma



  • Trauma


  • Iatrogenic


Cystitis Cystica



  • Degeneration of urothelial cells in Brunn nests


Other Neoplasm



  • Endometriosis


  • Metastases


PATHOLOGY


General Features



  • General path comments



    • ˜ 90% transitional cell carcinomas (TCC); often multifocal


    • 5-10% squamous cell (chronic inflammation)


    • < 5% mixed TCC and squamous cell


    • 2-3% adenocarcinoma (persistent urachal remnant)


    • < 1% rare types (e.g., leiomyomas, lymphoma, melanoma)


  • Etiology



    • Risk factors



      • Cigarette smoking


      • Exposure to aniline, aromatic amines, diesel fumes


      • Phenacetin use (once used as analgesic, now often mixed with cocaine)


      • Infection: Chronic urinary tract infection, schistosomiasis


  • Epidemiology



    • Most common tumor of urinary tract



      • More than 90% are transitional cell carcinoma


    • Men: Fourth most common cancer



      • 7% of all malignancies in men


    • Women: Tenth most common cancer



      • 2% of all malignancies in women

Sep 22, 2016 | Posted by in MAGNETIC RESONANCE IMAGING | Comments Off on Bladder Carcinoma
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