Small hepatocellular carcinoma: MRI findings for predicting tumor growth rates.

RATIONALE AND OBJECTIVES: Current clinical practice favors imaging rather than biopsy to diagnose hepatocellular carcinoma (HCC). There is a need to better understand tumor biology and aggressiveness of HCC. Our goal is to investigate magnetic resonance imaging (MRI) features of HCC that are associated with faster growth rates (GRs). MATERIALS AND METHODS: After approval from institutional review board, a retrospective evaluation was performed of pre-liver transplant patients. Fifty-two patients who developed a >2 cm HCC on serial imaging were included in the study group, with a total of 60 HCCs seen. Precursor foci were identified on serial MRIs before the specific diagnostic features of >2 cm HCC could be made, and GRs and MRI features, including signal on T1- and T2-weighted images (WI), the presence of intralesional steatosis on chemical shift imaging, and enhancement pattern were analyzed. GRs were correlated with imaging features. RESULTS: The average GR of precursor lesions to >2 cm HCC was determined to be 0.23 cm/mo (standard deviation [SD], 0.32), with a doubling time of 5.26 months (SD, 5.44). The presence of increased signal intensity (SI) on T2-WI was associated with significantly higher growth (P = .0002), whereas increased intensity on T1-WI at the initial study was associated with a significantly lower GR (P = .0162). Furthermore, lesions with hypervascular enhancement with washout pattern had significantly higher GR (P = .0164). There is no evidence of differences in GRs seen in lesions with steatosis. CONCLUSIONS: Small precursor lesions with increased SI on T2-WI and a washout pattern of enhancement are associated with faster GRs, which may suggest more aggressive tumor biology. These features may be helpful in patient management and surveillance for HCC.

Diffusion-weighted imaging (DWI) of adenomyosis and fibroids of the uterus.

PURPOSE: Although magnetic resonance imaging is often able to distinguish between adenomyosis and fibroids, occasionally the imaging features of focal adenomyosis and fibroids overlap. Diffusion-weighted imaging (DWI) may provide useful information in differentiating pathologies. Therefore, the purpose of our study was to evaluate differences, if any, in the apparent diffusion coefficient (ADC) values of fibroids and adenomyosis. MATERIAL AND METHODS: Patients (n = 50) with uterine fibroids and adenomyosis (n = 43), who underwent pelvic MR imaging including DWI, were included in this IRB approved HIPPA compliant retrospective study. DWI was performed with b factors of 50, 400, and 800 s/mm using a 1.5 T scanner. ADC ROI measurements were placed over a fibroid, an area of adenomyosis, unaffected normal myometrium, skeletal muscle, and urine. Histogram analysis of ADC maps in 20 cases each of adenomyosis and fibroids was evaluated to assess the degree of tissue heterogeneity. RESULTS: The ADC values of adenomyosis and fibroids were compared using Student's t test. The mean and the standard deviation of the ADC values of the control group were as follows: fibroid 0.64 ± 0.29, adenomyosis 0.86 ± 0.30, myometrium 1.39 ± 0.36, and urine 3.01 ± 0.2 × 10(-3) mm(2)/s. There was a statistically significant difference among the ADC values of normal myometrium and fibroids (p < 0.0001), normal myometrium and adenomyosis (p < 0.0001), and fibroids and adenomyosis (p < 0.001). Histogram analysis demonstrates less heterogeneity of adenomyosis as compared to fibroids. CONCLUSION: The present study shows that ADC measurements have the potential to quantitatively differentiate between fibroids and adenomyosis.