Kinetic Curves

Kinetic Curves

Julie A. Ritner, MD

Sagittal T1 C+ FS MR (left) and axial angiomap image (right) show a rapidly enhancing oval mass with spiculated margins image. Mixed kinetics image are seen. Pathology was grade II IDC.

Kinetics of the mass in the previous images show medium (50-100% at 90 sec) initial enhancement image with persistent (blue) image, plateau (yellow) image, and washout (red) image delayed-phase curves.


Abbreviations and Definitions

  • Kinetics: Dynamic contrast enhancement characteristics of lesion

    • Initial and delayed phases

    • Objective evaluation = plotted graph of ROI enhancement time-course points

      • Visual analysis is subjective; limited by progressive glandular enhancement

  • Enhancement

    • Post-contrast T1 signal intensity of lesion compared with pre-contrast signal

  • Dynamic acquisition

    • Sequential T1W FS imaging before and after contrast administration

    • Refers to temporal resolution

      • 1st post-contrast acquisition should be < 2 minutes after injection to capture peak initial enhancement

      • Peak enhancement may occur later

      • Ideally 60-90 seconds per acquisition

  • Region of interest (ROI)

    • Selected area within enhancing lesion for analysis of time-course kinetics

      • Selective ROI (3-4 pixels) important for accurate evaluation

      • Larger ROIs lead to averaging of kinetic features and falsely less suspicious appearance

      • Can be drawn manually and plotted over time

      • ROI summaries can be generated by computer-aided detection (CAD) software

      • Most suspicious enhancement should be reported

  • Time-signal intensity curve (TIC) = kinetic curve

    • Graph of ROI pixel value over time

    • Initial phase: Enhancement pattern within 1st 2 minutes or when curve starts to change (per BI-RADS)

    • Delayed phase: Enhancement pattern after 1st 2 minutes or when curve starts to change (per BI-RADS)

  • Maximum intensity projection (MIP)

    • 3D reconstruction of 1st post-contrast subtraction series

  • Subtraction series

    • Post-processed images created by subtracting pre-contrast series from selected post-contrast series

      • Clearly displays areas of enhancement

    • Used in 2D imaging as “fat-suppressed” images

    • Patient motion may lead to image misregistration and false depiction of enhancement

    • MIP images generated from 1st post-contrast subtraction series

  • Signal intensity (SI)

  • Dynamic contrast-enhanced (DCE) MR = modified post-contrast acquisition

    • Very high temporal resolution at expense of spatial resolution

    • To assess physiologic parameters (vessel permeability, tissue perfusion, & others)

      • Research evaluating neoadjuvant chemotherapy response


Initial Phase

  • Early enhancement, determined by signal change from baseline pre-contrast series to 1st post-contrast series

  • Most optimal phase for cancer detection: Greatest T1 difference between enhancing cancer and background

  • Predictive kinetic feature

  • Qualitative and quantitative assessment described

    • Qualitative: Visual assessment of enhancement intensity

    • Quantitative: Calculated assessment, used for kinetic curve analysis

      • Defined as percent signal increase from pre-contrast signal to 1st post-contrast series

      • Slow, medium, rapid

  • Threshold of initial phase determines presence or absence of CAD color assignment

    • Below threshold: Slow enhancement (< 50% SI increase) does not receive color assignment

      • Typically benign, though morphology must determine level of suspicion

      • Time-course not predictive for level of suspicion

    • Lower threshold: Medium (> 50% SI increase) and rapid receive color assignment

    • Higher threshold: Only rapid (≥ 100% SI increase) receives color assignment

      • Invasive cancers typically show rapid enhancement

      • Benign parenchyma, benign proliferative and inflammatory lesions, and benign lymph nodes may show rapid enhancement

    • Can be manually adjusted to different levels of sensitivity

Delayed (Post-Initial) Phase

  • Kinetic time point analysis after initial phase

    • Variable number of delayed time points depending on temporal resolution, typically 4-6

    • Peak enhancement may occur in initial phase or later in delayed phase

    • Minimum of 1 point required (4-7 minutes post-injection) to define curve shape

  • Curve type determined by time point analysis after peak enhancement

    • Type I curve = persistent: > 10% continued increase in signal intensity after peak enhancement

      • Typically benign pattern, though suspicious morphology should prompt biopsy

      • Multiple foci of persistent enhancement may be benign pattern (may be described as moderate or marked background enhancement)

    • Type II curve = plateau: Steady signal intensity after peak enhancement

      • ± 10% of peak signal intensity

      • Suspicious pattern: 64-77% PPV for malignancy

    • Type III curve = washout: > 10% decrease in signal intensity after peak enhancement

      • Highly suspicious pattern: 87-92% PPV

      • Washout may occur in later delayed phase (at 3-4 minutes), considered suspicious

      • Benign lesions may show washout, lowering specificity: Lymph nodes, adenosis, papillomas

  • Identification of curve shapes has high interobserver agreement (κ = 0.85)


    • Software programs that automate image post-processing, in particular regarding enhancement kinetics

      • Kinetics demonstrated by color-coded parametric overlays in areas of threshold enhancement

    • Post-processing is subject to potential errors

      • Rigorous quality control is essential to avoid misdiagnoses and false-negative interpretations

      • Cardiac kinetic curve (rapid enhancement with washout) verifies contrast administration and correct processing

      • Knowledge of software limitations, artifacts, and potential pitfalls is important

  • Threshold enhancement

    • Presence of CAD color assignment based on initial enhancement reaching selected threshold

  • Generates color parametric overlay of enhancement kinetics, subtraction and MIP images, and ROI summaries

    • Parametric kinetic mapping shows color overlay of areas that reach threshold enhancement

      • Specific color assignment based on delayed-phase enhancement curves (type I, II, or III); color assignments vary with each vendor

      • False washout color assignment can be seen with misregistration from patient motion

      • Absence of color assignment of rapidly enhancing masses can occur with incorrect image processing

    • MIPs useful for background enhancement, vascularity, and focal enhancing lesions

      • Increased breast vascularity associated with invasive cancers

    • ROI summaries

      • Enhancement curves are generated on pixel by pixel basis

  • MR interpretation should not be based solely on CAD-generated images

    • CAD images are post-processed and may show false analyses if processed incorrectly

    • Source images must always be reviewed



  • High MR sensitivity for cancer detection largely due to rapid enhancement of invasive carcinomas

    • Reported sensitivity, specificity, and accuracy of TIC

      analysis: 91-96%; 83-86%; 86%

    • Enhancement occurs in benign lesions and normal fibroglandular tissue

    • Kinetic analysis improves specificity

  • High temporal resolution essential for accurate kinetic analysis

Anatomic Considerations

  • Enhancement related in part to vessel density and capillary permeability

    • Benign fibroglandular tissue is hormonally responsive and may show suspicious enhancement

    • Tumor neovascularity causes rapid enhancement and washout


  • Most predictive feature: Margin morphology > enhancement kinetics

  • Presence of any type of enhancement is important

    • Typical invasive cancers show rapid enhancement with plateau or washout kinetics

    • Up to 15% of invasive malignancies may show slow enhancement

    • 94-100% NPV for nonenhancement to exclude invasive cancer


  • Morphology > > kinetics

    • Slow enhancement with delayed peak could lead to false-negative interpretation

    • 20% of invasive cancers in high-risk patients were NMLE (1 series)

  • 70-96% sensitivity for MR DCIS detection

    • 10-16% of DCIS lesions show no enhancement

  • Symmetry useful to determine level of suspicion

Kinetic Analysis Pitfalls

  • 1st post-contrast scan > 2 minutes

    • Misses peak enhancement, falsely benign curve

  • False-negative study

    • Absent contrast

      • Suspect with strongly “negative” MIP

      • Validate contrast injection: Cardiac kinetic curve

    • Cancer not included in field of view

    • Excessive compression, limits enhancement

    • Incorrect post-processing

  • Misregistration due to patient motion

    • Suspect with nonphysiologic jagged curve shape

    • May mimic suspicious enhancement

    • Edge artifact = color artifact at fat-parenchyma interfaces


1. Kuhl C: The current status of breast MR imaging. Part I. Choice of technique, image interpretation, diagnostic accuracy, and transfer to clinical practice. Radiology. 244(2):356-78, 2007

2. Lehman CD et al: A new automated software system to evaluate breast MR examinations: improved specificity without decreased sensitivity. AJR Am J Roentgenol. 187(1):51-6, 2006

3. Schnall MD et al: Diagnostic architectural and dynamic features at breast MR imaging: multicenter study. Radiology. 238(1):42-53, 2006

4. Kuhl CK et al: Dynamic bilateral contrast-enhanced MR imaging of the breast: trade-off between spatial and temporal resolution. Radiology. 236(3):789-800, 2005

5. Szabó BK et al: Dynamic MR imaging of the breast. Analysis of kinetic and morphologic diagnostic criteria. Acta Radiol. 44(4):379-86, 2003

Image Gallery

Kinetic curve analysis includes initial phase, defined as percent signal change from pre-contrast, at 90 secs to 2 mins. Rapid & medium enhancement typically get color assignments. Slow enhancement does not receive color.

Delayed-phase enhancement determines curve type. Type 1 = persistent (blue); type 2 = plateau (yellow); type 3 = washout (red). Color assignments vary by CAD vendors.

(Left) Staging MR in a 41 year old with a palpable mass, malignant on FNA, shows the malignancy as a heterogeneously enhancing round mass with spiculated margins on dynamic sagittal (left) and delayed axial (right) image images. (Right) Sagittal T1WI C+ FS MR (left) and axial delayed image (right) of the same breast show a 2nd mass, oval, smooth, with nonenhancing septations, and rapid initial and plateau delayed enhancement image.

(Left) Sagittal T1WI C+ FS MR with color shows the known malignancy to have rapid initial enhancement (color assignment) with dominantly persistent (type I: Blue) and plateau (type II: Yellow) delayed kinetics. (Right) Sagittal T1WI C+ FS MR with CAD color overlay shows the 2nd mass to have rapid initial enhancement and only persistent (blue) delayed kinetics. Morphology and kinetics suggest a probably benign mass. Biopsy proved a fibroadenoma.

(Left) Kinetic curve from the same known malignancy shows rapid initial-phase enhancement (> 100% at 90 seconds) image with persistent (type I: Blue) image and plateau (type II: Yellow) image delayed-phase curves. (Right) Kinetic curve from the fibroadenoma shows rapid initial enhancement (> 100% at 90 seconds) image and persistent (type I) image delayed enhancement.

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Sep 18, 2016 | Posted by in OBSTETRICS & GYNAECOLOGY IMAGING | Comments Off on Kinetic Curves
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