Feasibility of small bowel flow rate measurement with MRI.

OBJECTIVE: To evaluate whether it is feasible to measure the segmental flux of small bowel content using MR phase-contrast (PC) pulse sequences. MATERIALS AND METHODS: Using a phantom the accuracy of flux measurements was validated. Afterwards, 10 volunteers were included in a prospective clinical trial. To provide standardized small bowel distension, all volunteers ingested four equal portions of 400 mL of water doped with 5 mL gadoterate and 5.8 g Metamucil mite. The MR protocol covering the sagittal cross-sections of the small bowel included several two-dimensional (2D) PC sequences with a velocity encoding of 7 cm/second at a temporal resolution of 0.55 second. As proof of concept time-dependent flux was measured after intravenous (i.v.) administration of a spasmolytic agent in one volunteer. RESULTS: Phantom measurements resulted in an excellent correlation between pump and PC measured flow rates (R = 0.999). Time-resolved small bowel flux was successfully measured in distended small bowel loops of all volunteers. A mean flow rate of 0.188 mL/second (standard deviation +/- 0.144 mL/second) was documented. The flux plots presented a sinus wave-like shape with regular aboral and oral flow. A spasmolytic effect both on flux and motility could be shown with residual flux despite complete arrest of small bowel motility. CONCLUSION: PC MRI allows time-resolved in vivo measurement of small bowel flux in single well-distended bowel loops filled with gadolinium-doped aqueous solution.

Comparison of diffusion-weighted whole body MRI and skeletal scintigraphy for the detection of bone metastases in patients with prostate or breast carcinoma.

PURPOSE: To prospectively compare the diagnostic accuracy of diffusion-weighted whole body imaging with background whole body signal suppression (DWIBS) with skeletal scintigraphy for the diagnosis and differentiation of skeletal lesions in patients suffering from prostate or breast cancer. MATERIAL AND METHODS: A diagnostic cohort of 36 patients was included in skeletal scintigraphy and 1.5 T DWIBS MRI. Based on morphology and signal intensity patterns, two readers each identified and classified independently, under blinded conditions, all lesions into three groups: (1) malignant, (2) unclear if malignant or benign and (3) benign. Finally, for the definition of the gold standard all available imaging techniques and follow-up over a minimum of 6 months were considered. RESULTS: Overall, 45 circumscribed bone metastases and 107 benign lesions were found. DWIBS performed significantly better in detecting malignant skeletal lesions in patients with more than 10 lesions (sensitivity: 0.97/0.91) compared to skeletal scintigraphy (sensitivity: 0.48/0.42). No statistical difference could be found between DWIBS (0.58/0.33) and skeletal scintigraphy (0.67/0.58) in the sensitivity values for malignant skeletal lesions in patients with less than 5 lesions. For benign lesions, scintigraphy scored best with a sensitivity of 0.93/0.87 compared to 0.20/0.13 for DWIBS. Interobserver agreement with Cohen's kappa coefficient was calculated as 0.784 in the case of scintigraphy and 0.663 for DWIBS. CONCLUSION: With respect to staging, in prostate and breast carcinoma, the DWIBS technique is not superior to skeletal scintigraphy, but ranks equally. However, in the cases with many bone lesions, markedly more metastases could be discovered using the DWIBS technique than skeletal scintigraphy.

Clinical experience in timed arterial compression contrast-enhanced magnetic resonance angiography of the hand.

PURPOSE: A retrospective analysis of the diagnostic performance of the timed arterial compression (TAC) technique, which allows freezing of the contrast bolus during first-pass contrast-enhanced (CE) magnetic resonance angiography (MRA) to diagnose vascular pathologies in the hand. MATERIAL AND METHODS: A total of 14 consecutive CE-MRAs of the hand were acquired by using the TAC technique. By inflating a blood pressure cuff up to 200 mm Hg triggered to the arterial contrast filling of the hand, prolonged measurement times up to 144 seconds, with a spatial resolution of 0.59 × 0.59 × 0.8 mm(3), could be realized. Overall image qualities, arterial signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), and vessel conspicuity besides the final diagnosis were evaluated. RESULTS: All 14 TAC-CE-MRAs of the hand were successfully accomplished without any adverse events and yielded, in all cases, a final diagnosis with a high total number of vascular pathologies (57). High arterial SNR and CNR values exceeding the soil of 85 and 60, respectively, resulted. Thus, overall vessel visibility (>90%), vessel conspicuity (mean Δ signal intensity [SI]/mm = 1,193) and image quality on a per patient level (>60%) were rated as excellent or good. CONCLUSIONS: TAC-CE-MRA of the hand offers high diagnostic performance because of its increased spatial resolution while preserving contrast, which allowed detection of tiny stenoses of the digital arteries.