Fig. 4

Assessment of spinal dynamic contrast-enhanced MRI to obtain qualitative time-intensity curves (a), semi-quantitative (b), and quantitative (c) parametric maps and features of regions-of-interest in the spine and of reference tissues in the same patient as in Fig. 3. Cortical endplates, basivertebral veins, normal anatomical variants, and benign lesions like Schmorl’s nodules and Modic changes were avoided during segmentation. Regions-of-interest and reference tissue segmentations were matched with the anatomical sequences for optimal detailed segmentation. a Suspected focal lesions ≥ 5 mm in the 10th thoracic, 1st lumbar, and 1st sacral vertebra (arrows on the sagittal spinal dynamic contrast-enhanced MRI T1 Twist sequence, 50 s after gadolinium contrast administration) (Gadovist 7.5 mL, gadobutrol 1.0 mmol/mL, 0.1 mmol/kg, Bayer) and diffuse abnormal signal intensities can be observed in the spinal bone marrow. On the derived time-intensity curve, the thoracic and lumbar vertebral bone marrow (L3-third lumbar vertebra; T9-ninth thoracic vertebra) show active type IV curves with a steep first pass corresponding to high perfusion, high tissue vascularization, and low capillary resistance. The steep wash-in of a type IV curve and strong wash-out depict the effect of a highly vascularized region in combination with a small interstitial space. The suspected focal lesions in the 1st lumbar (FL L1) and 1st sacral (FL S1) vertebrae also show active type IV curves. The suspected focal lesion in the 10th thoracic (FL T10) vertebra shows an inactive type I curve without enhancement which is comparable to the reference paravertebral muscle vascularization, indicative of its benign character due to a recent compression fracture. Remark that the diffuse bone marrow infiltration also shows a type IV curve, indicative that active myeloma disease invades the entire spine diffusely. b Sagittal spinal positive enhancement integral parametric map generated in SyngoVia VB60 (Siemens) postprocessing software to assess the semi-quantitative features describing the time-intensity curve. Extracted features are wash-in, wash-out, arrival time, positive enhancement integral, time-to-peak, and initial area-under-the-time-intensity-curve (60 s). E.g. the positive enhancement integral is low (0.033) in the paravertebral muscles as reference tissue. The bone marrow of the ninth thoracic vertebral body and the focal lesion in the first lumbar vertebra have a positive enhancement integral of 0.244 and 0.441, respectively, which is 7–13 times higher than that of the reference muscle. c Sagittal spinal Ktrans (volume transfer constant) parametric map generated in SyngoVia VB60 (Siemens) postprocessing software to assess the quantitative features resulting from the Tofts model describing the time-concentration curve. Extracted features are Ktrans (volume transfer constant), Kep (rate constant), Ve (volume of the extracellular extravascular space), and initial area-under-the-time-concentration-curve (60 s). E.g. the Ktrans is low (0.094) in the paravertebral muscles as reference tissue. The bone marrow of the ninth thoracic vertebral body and the focal lesion in the first lumbar vertebra have a Ktrans of 1.094 and 1.494, respectively, which is 12–16 times higher than that of the reference muscle. Ao aorta, AT arrival time, A.U. arbitrary unit, DCE-MRI dynamic contrast-enhanced magnetic resonance imaging, FL focal lesion, iAUC initial area-under-the-curve, Kep rate constant, Ktrans volume transfer constant, L1/L3 first/third lumbar vertebra, PEI positive enhancement integral, s second, S1 first sacral vertebra, sag sagittal, SI signal intensity, T1 T1-weighted, T9/T10 ninth/tenth thoracic vertebra, TCC time-concentration curve, TIC time-intensity curve, TTP time-to-peak, Ve volume of the extracellular extravascular space, vs. versus