Evaluation of locally recurrent pelvic malignancy: performance of T2- and diffusion-weighted MRI with image fusion.

PURPOSE: To evaluate the performance of T2- and diffusion-weighted magnetic resonance imaging (MRI) with image fusion for detection of locally recurrent pelvic malignancy. MATERIALS AND METHODS: The study group consisted of 28 patients (27 female, 1 male) who underwent pelvic MRI at 1.5 T after treatment of pelvic malignancy. MR images were reviewed independently by three blinded readers. The performance of the four sequences for detecting local recurrence was evaluated using receiver operating characteristic analysis: T2-weighted fast spin-echo (FSE), diffusion-weighted echo-planar imaging (DWI), dynamic contrast-enhanced (DCE) fat-suppressed T1-weighted spoiled gradient echo (SPGR), and T2-DWI with image fusion, the latter created using OsiriX Medical Imaging Software. RESULTS: Local recurrence was confirmed at biopsy in 16 patients. Twelve patients showed no evidence of recurrence on two consecutive MRI studies. The Az value for T2-DWI with image fusion (0.949) was statistically greater than that for T2-weighted FSE (0.849) (P<0.05). The sensitivity and specificity was 87.5% and 47.2%, respectively, for T2-weighted FSE, 100.0% and 50.0% for DWI, 95.8% and 58.3% for DCE fat-suppressed T1-weighted SPGR, and 93.8% and 72.2% for T2-DWI with image fusion. CONCLUSION: For depicting locally recurrent pelvic malignancy, T2-DWI with image fusion outperforms standard T2-weighted FSE and DWI and is comparable to DCE fat-suppressed T1-weighted SPGR.

Gadolinium-enhanced fat-suppressed T1-weighted imaging for staging ureteral carcinoma: correlation with histopathology.

OBJECTIVE: The purpose of this study was to retrospectively compare contrast-enhanced fat-suppressed T1-weighted images with histopathologic findings in ureteral carcinoma to develop accurate preoperative MR criteria for T staging. CONCLUSION: Contrast-enhanced fat-suppressed T1-weighted images can be used to distinguish thickened noncarcinomatous ureteral walls, which occur due to the proliferation of fibrous tissue, from ureteral carcinoma because fibrous tissue enhances more intensely on MRI than ureteral carcinoma. We also observed that when ureteral carcinomas had invaded periureteral fat tissue, a disruption or fragmentation of the intensely enhancing ureteral wall was seen. Using the MR criteria for T staging that we developed on the basis of these findings, we were able to accurately determine whether a carcinoma had invaded periureteral fat tissue in all of our patients.

Preliminary examination to determine the suitable contrast material injection protocol for CT angiography of the pelvis and lower extremities with a multidetector row helical scanner.

PURPOSE: The aim of this study was to determine the best of three protocols for the depiction of arteries in the pelvis and lower extremities by computed tomographic angiography (CTA) with a multidetector row helical scanner. MATERIALS AND METHODS: CTA was performed in five asymptomatic volunteers using a four-channel multidetector row helical scanner. Low-osmolar iodinated contrast material was injected at the flow rate of 3 ml/s using three protocols: 100 ml of 300 mg I/ml, 150 ml of 300 mg I/ml, and 100 ml of 350 mg I/ml. The CT number of opacified blood was measured at six levels. Three doctors independently assessed the degree of depiction of arteries on CTA images without knowing the protocol using a 3-point scale. RESULTS: CT numbers at the level of the popliteal artery on the protocol of 150 ml of 300 mg I/ml were significantly greater than the others. The mean score for the depiction of trifurcation on the protocol of 150 ml of 300 mg I/ml was significantly greater than those in the others. CONCLUSION: The protocol of 150 ml of 300 mg I/ml was the best for depicting arteries in the pelvis and lower extremities by CTA.

[Evaluation of ultra-low-dose thoracic multi-detector-row CT using different reconstruction kernels and new reconstruction algorithms].

CT has great advantages in detecting early-stage small lung cancer and is becoming common in lung cancer screening. Multi-detector-row CT (MDCT) can provide thin-slice images with low radiation exposure. In this study, ultra-low-dose (5 mAs: 10 mAs, 0.5 sec/rot) thoracic MDCT images were evaluated. We describe the differences in image quality and quantity between the different reconstruction kernels. We also propose a new reconstruction algorithm (ultra-low-dose reconstruction algorithm: ULR) for ultra-low-dose thoracic CT, to reduce noise and streak artifacts. We are convinced of the usefulness and possibility of ultra-low-dose thoracic MDCT with ULR algorithms for lung cancer screening.

Artifacts of vena cava filters ex vivo on MR angiography.

We evaluated magnetic susceptibility artifacts of nine types of vena cava filters in MR angiography (MRA) at 1.0T ex vivo in order to assess the filters' compatibility with MRA. Each filter (tulip filter, tulip MReye filter, stainless Greenfield filter, titanium Greenfield filter, TrapEase filter, Simon filter, LGM Vena-Tech filter, Antheor temporary filter, and Bird's nest filter) was inserted into an acrylic tube (20 or 25 mm in diameter, 15 or 30 cm in length). Gd-DTPA was poured into each tube at a concentration of 1/500 and each was placed in a water-filled container for imaging. We evaluated artifacts of the filters according to the following criteria: signal void beyond the tube, 3+; signal void within the tube but at more than one-half the diameter of the tube, 2+; and signal void within the tube but at less than one-half the diameter of the tube, 1+. We evaluated artifacts originating at the tip, intermediate portion, and distal end of the filters. We judged the artifacts as follows: tulip (3+, 3+, 3+); tulip MReye (2+, 1+, 1+); stainless Greenfield (2+, 1+, 2+); titanium Greenfield (1+, 1+, 1+); TrapEase (1+, 2+, 1+); Simon (2+, 2+, 1+); LGM (2+, 2+, 1+); Antheor (2+, 2+, 2+); and Bird's nest (3+, 3+, 3+). The numbers in parentheses refer to the degree of signal void at the tip, intermediate portion, and distal end of the filter, respectively. The tulip filter and Bird's nest filter made of 304 stainless steel caused extensive signal voids beyond the areas defined by the filters. The signal voids in the remaining seven filters were limited to within the tube. We concluded that seven of the nine filters were compatible with MRA ex vivo.

Moderately T2-weighted images obtained with the single-shot fast spin-echo technique: differentiating between malignant and benign urinary obstructions.

The purpose of this study was to determine whether a distinction could be made between benign and malignant urinary obstructions in moderately T(2)-weighted images obtained with the single-shot fast spin-echo technique. Forty-four lesions in 39 patients with urinary obstruction were evaluated with the single-shot fast spin-echo (SSFSE) technique with an effective TE of 90-100 ms and without fat saturation. Benign and malignant lesions were compared for the presence of ureteral wall thickening and a signal intensity relative to the proximal ureteral wall. Statistically significant differences were found between benign and malignant lesions in both morphologic change (P<0.0001) and signal intensity of the lesions at the obstruction position (P<0.0001). The combination of wall thickening and increased signal intensity as a predictor of malignant disease yielded a sensitivity of 88% and a specificity of 100%. Neither increased signal intensity nor wall thickening as a predictor of benign disease yielded a sensitivity of 89% and a specificity of 88%. The moderately T(2)-weighted SSFSE technique without fat saturation can accurately distinguish between benign and malignant urinary obstructions.