Comparison of MRI features of pathologically proven hepatocellular carcinoma between patients with hepatitis B and hepatitis C infection.

PURPOSE: To compare MRI features of pathologically-proven hepatocellular carcinoma (HCC) between patients with hepatitis B (HBV) and hepatitis C (HCV) infection. METHODS: Two radiologists assessed 51 confirmed HCCs on MRI in HBV (n=18) or HCV (n=33) patients; a third, more experienced, radiologist resolved discrepancies. RESULTS: Arterial hyperenhancement occurred more frequently in HCV (90.9% vs. 66.7%; P=.032), DWI/T2WI hyperintensity more frequently in HBV [(DWI: 78.6% vs. 45.8%, T2WI: 77.8% vs. 48.5%; P=.073-0.088)]. Tumors were larger in HBV (P≤.016). Washout, pseudocapsule, homogeneity, circumscribed margins, lipid, iron, and visually low ADC were not different. CONCLUSION: Larger studies are required to confirm these preliminary findings.

Investigation of Multisequence Magnetic Resonance Imaging for Detection of Recurrent Tumor After Transurethral Resection for Bladder Cancer.

PURPOSE: The aim of this study was to evaluate multisequence magnetic resonance imaging (MRI) in detecting local recurrence after transurethral resection for bladder cancer. METHODS: Thirty-six patients with bladder cancer with previous transurethral resection underwent bladder MRI incorporating T2-weighted imaging, diffusion-weighted imaging, and delayed contrast-enhanced T1-weighted imaging, followed by cystoscopy. Two radiologists (R1 and R2) evaluated examinations for suspicious findings. RESULTS: Forty-seven percent of patients had recurrent tumor at cystoscopy and biopsy. Using multisequence MRI, sensitivity and specificity were 67% and 81% for R1 and 73% and 62% for R2. Both readers missed 1 high-grade pathologic stage T1 recurrent tumor; otherwise, all missed tumors were low-grade pathologic stage Ta lesions. All false positives for R1 and 7 of 9 false positives for R2 were in patients receiving previous bacillus Calmette-Guerin therapy. Furthermore, 40% to 50% of solitary abnormalities and 83% to 100% of multifocal abnormalities were tumor recurrences; 12% to 20% of smooth wall thickening, 50% to 75% of irregular wall thickening, and 88% to 100% of papillary masses were tumor recurrences. CONCLUSIONS: Although multisequence MRI exhibited moderate performance for detecting recurrent tumor, nearly all missed tumors were low grade and noninvasive.

Directional asymmetry of pelvic vestiges in threespine stickleback.

Extensive reduction of the size and complexity of the pelvic skeleton (i.e., pelvic reduction) has evolved repeatedly in Gasterosteus aculeatus. Asymmetrical pelvic vestiges tend to be larger on the left side (i.e., left biased) in populations studied previously. Loss of Pitx1 expression is associated with pelvic reduction in G. aculeatus, and pelvic reduction maps to the Pitx1 locus. Pitx1 knockouts in mice have reduced hind limbs, but the left limb is larger. Thus left-biased directional asymmetry of stickleback pelvic vestiges may indicate the involvement of Pitx1 in pelvic reduction. We examined 6,356 specimens from 27 Cook Inlet populations of G. aculeatus with extensive pelvic reduction. Samples from 20 populations exhibit the left bias in asymmetrical pelvic vestiges expected if Pitx1 is involved, and three have a slight, non-significant left bias. However, samples from three populations have a significant right bias, and one large sample from another population has equal frequencies of specimens with larger vestiges on the left or right side. A sample of fossil threespine stickleback also has significantly left-biased pelvic vestiges. These results suggest that silencing of Pitx1 or the developmental pathway in which it functions in the pelvis is the usual cause of pelvic reduction in most Cook Inlet populations of G. aculeatu, and that it caused pelvic reduction at least 10 million years ago in a stickleback population. A different developmental genetic mechanism is implicated for three populations with right-biased pelvic vestiges and for the population without directional asymmetry.