C-arm CT for assessing initial failure of iodized oil accumulation in chemoembolization of hepatocellular carcinoma.

OBJECTIVE: The purpose of our study was to assess the feasibility of using C-arm CT to detect incomplete accumulation of iodized oil in hepatocellular carcinoma immediately after transarterial chemoembolization (TACE). MATERIALS AND METHODS: This retrospective study included 80 hepatocellular carcinoma lesions in 55 patients (41 men and 14 women; mean age, 69.2 years; mean tumor size, 18.1 mm [range, 5-55 mm]) who underwent TACE with a flat-detector C-arm angiographic system. C-arm CT images were acquired at the end of each session, and unenhanced MDCT images were obtained 7 days later. Two independent observers scored both sets of images, using a predefined detection scale for incomplete iodized oil accumulation. The accuracy for predicting residual lesions was compared using the area under the receiver-operating characteristic curve (A(z)). Contrast-enhanced CT findings obtained 1 month after TACE served as reference standards. RESULTS: Viable lesions were observed in 18 of the 80 study lesions by contrast-enhanced CT. The accuracy of the C-arm CT (A(z) = 0.816) was not significantly different (p = 0.449) from that of the MDCT (A(z) = 0.841). Sensitivity, specificity, and positive and negative predictive values for C-arm CT (80.5%, 74.2%, 47.5%, and 92.9%, respectively) and MDCT (86.1%, 75.0%, 50.0%, and 94.9%, respectively) did not differ significantly. CONCLUSION: C-arm CT is nearly equivalent to MDCT for detecting incomplete iodized oil accumulation after TACE, suggesting that the immediate assessment of iodized oil accumulation with C-arm CT without the need to perform follow-up unenhanced MDCT is likely feasible.

Prostate cancer detection with MRI: is dynamic contrast-enhanced imaging necessary in addition to diffusion-weighted imaging?

PURPOSE: To assess the feasibility of using magnetic resonance imaging for prostate cancer detection without using a contrast material. MATERIALS AND METHODS: T2-weighted imaging (T2WI), diffusion-weighted imaging (DWI), and dynamic contrast-enhanced imaging (DCEI) were performed using a phased-array coil at 1.5 T. These examinations were performed in 178 patients with elevated serum prostate-specific antigen levels ( > 4.0 ng/mL) before systematic needle biopsy. Two radiologists independently evaluated images from DWI, DCEI, and a combination of the two techniques by referring to a T2WI image and by using a predefined confidence scale for cancer detection. The right and left halves of the peripheral zone and the central gland were separately rated. The diagnostic performance (A < sub > z < /sub > ) of each technique was assessed by analyzing their associated area under the receiver operating characteristic curves. The results of a biopsy served as a reference standard. RESULTS: Prostate cancer was detected in 72 (40.4%) of the 178 patients. For the entire prostate, the diagnostic performances of DWI (Az = 0.848) (P < 0.001) and the combined technique (Az = 0.845) (P < 0.001) were significantly more accurate than that of DCEI (Az = 0.746). DWI (74.8%) (P < 0.001) and the combined technique (72.9%) (P < 0.001) were significantly more sensitive than DCEI (52.8%). The numbers of cancer lesions that were interpreted using only DWI or DCEI were 83 (26.1%) and 13 (4.1%) of the 318 study lesions, respectively. CONCLUSION: DWI and the combined technique are more accurate and sensitive than DCEI in the detection of prostate cancer; however, DWI and DCEI play complementary roles in the accurate detection of prostate cancer.