Jeong Kyong Lee

Usefulness of T1-weighted image with fast inversion recovery technique in intracranial lesions: comparison with T1-weighted spin echo image

To evaluate the usefulness of T1-weighted images using the fast inversion recovery (T1FIR) technique as compared with routine T1-weighted spin echo (T1SE) images in various intracranial lesions. Routine spin echo and T1FIR images were performed in 15 consecutive patients with 18 lesions, cerebral infarction in five, astrocytoma in four, vascular lesion in three, encephalomalacia and hemorrhage in each two, arachnoid cyst and meningioma in each one. T1FIR images were performed with 1.5-T Signa [repetition time (TR)/echo time (TE)/inversion time (TI) was 2000/34/800 in 14, 4000/34/1200 in four lesions] and qualitatively compared with the T1SE images in signal intensity, lesion detectability, determination of lesion extent and conspicuity, contrast between lesion and background. Additionally, gray-to-white matter and cerebrospinal fluid (CSF)-to-white matter contrast were evaluated. The signal intensity of the lesions was similar on both T1FIR and T1SE images in all cases. The lesion detectability was similar on both sequences in 15 lesions, and the determination of the lesion extent was definitely higher in 16 lesions on the T1FIR images. Lesion conspicuity was superior in 11, similar in 5, and inferior in 2 patients on the T1FIR images. And also, contrast of lesion-to-background, gray-to-white matter, and CSF-to-white matter was superior on the T1FIR images. The T1FIR technique improved the determination of lesion extent and lesion conspicuity and was qualitatively superior for image contrast as compared with T1SE, but it takes more time than T1SE. The clinical application of T1FIR images depends on whether the superior aspect of the T1FIR images outweighs the disadvantage of the longer time required for this technique.

Dual-Energy CT in the Assessment of Mediastinal Lymph Nodes: Comparative Study of Virtual Non-Contrast and True Non-Contrast Images

Objective To evaluate the reliability of virtual non-contrast (VNC) images reconstructed from contrast-enhanced, dual-energy scans compared with true non-contrast (TNC) images in the assessment of high CT attenuation or calcification of mediastinal lymph nodes. Materials and Methods A total of 112 mediastinal nodes from 45 patients who underwent non-contrast and dual-energy contrast-enhanced scans were analyzed. Node attenuation in TNC and VNC images was compared both objectively, using computed tomography (CT) attenuation, and subjectively, via visual scoring (0, attenuation ≤ the aorta; 1, > the aorta; 2, calcification). The relationship among attenuation difference between TNC and VNC images, CT attenuation in TNC images, and net contrast enhancement (NCE) was analyzed. Results CT attenuation in TNC and VNC images showed moderate agreement (intraclass correlation coefficient, 0.612). The mean absolute difference was 7.8 ± 7.6 Hounsfield unit (HU) (range, 0-36 HU), and the absolute difference was equal to or less than 10 HU in 65.2% of cases (73/112). Visual scores in TNC and VNC images showed fair agreement (κ value, 0.335). Five of 16 nodes (31.3%) which showed score 1 (n = 15) or 2 (n = 1) in TNC images demonstrated score 1 in VNC images. The TNC-VNC attenuation difference showed a moderate positive correlation with CT attenuation in TNC images (partial correlation coefficient [PCC] adjusted by NCE: 0.455) and a weak negative correlation with NCE (PCC adjusted by CT attenuation in TNC: -0.245). Conclusion VNC images may be useful in the evaluation of mediastinal lymph nodes by providing additional information of high CT attenuation of nodes, although it is underestimated compared with TNC images.

CT Characteristics of Pleural Plaques Related to Occupational or Environmental Asbestos Exposure from South Korean Asbestos Mines.

Objective This study evaluated the CT characteristics of pleural plaques in asbestos-exposed individuals and compared occupational versus environmental exposure groups. Materials and Methods This study enrolled 181 subjects with occupational exposure and 98 with environmental exposure from chrysotile asbestos mines, who had pleural plaques confirmed by a chest CT. The CT scans were analyzed for morphological characteristics, the number and distribution of pleural plaques and combined pulmonary fibrosis. Furthermore, the CT findings were compared between the occupational and environmental exposure groups. Results Concerning the 279 subjects, the pleural plaques were single in 2.2% and unilateral in 3.6%, and showed variable widths (range, 1-20 mm; mean, 5.4 ± 2.7 mm) and lengths (5-310 mm; 72.6 ± 54.8 mm). The chest wall was the most commonly involved (98.6%), with an upper predominance on the ventral side (upper, 77.8% vs. lower, 55.9%, p < 0.001) and a lower predominance on the dorsal side (upper, 74.9% vs. lower, 91.8%, p = 0.02). Diaphragmatic involvement (78.1%) showed a right-side predominance (right, 73.8% vs. left, 55.6%, p < 0.001), whereas mediastinal plaques (42.7%) were more frequent on the left (right, 17.6% vs. left, 39.4%, p < 0.001). The extent and maximum length of plaques, and presence and severity of combined asbestosis, were significantly higher in the occupational exposure group (p < 0.05). Conclusion Pleural plaques in asbestos-exposed individuals are variable in number and size; and show a predominant distribution in the upper ventral and lower dorsal chest walls, right diaphragm, and left mediastinum. Asbestos mine workers have a higher extent of plaques and pulmonary fibrosis versus environmentally exposed individuals.

US characteristics for the prediction of neoplasm in gallbladder polyps 10 mm or larger.

PurposeTo evaluate the characteristics of gallbladder polyps 10 mm or larger to predict a neoplasm in US examinations.Materials and methodsFifty-three patients with gallbladder polyps ≥ 10 mm with follow-up images or pathologic diagnosis were included in the retrospective study. All images and reports were reviewed to determine the imaging characteristics of gallbladder polyps. Univariate and multivariate analyses were used to evaluate predictors for a neoplastic polyp.ResultsA neoplastic polyp was verified in 12 of 53 patients and the mean size was 13.9 mm. The univariate analysis revealed that adjacent gallbladder wall thickening, larger size (≥15 mm), older age (≥57 years), absence of hyperechoic foci in a polyp, CT visibility, sessile shape, a solitary polyp, and an irregular surface were significant predictors for a neoplastic polyp. In the multivariate analysis, larger size (≥15 mm) was a significant predictor for a neoplastic polyp.ConclusionA polyp size ≥15 mm was the strongest predictor for a neoplastic polyp with US. The hyperechoic foci in a polyp and CT visibility would be useful indicators for the differentiation of a neoplastic polyp, in addition to the established predictors.Key Points• A polyp size ≥15 mm is the strongest predictor for a neoplastic polyp with US.• Hyperechoic foci in a polyp and CT visibility are new predictors.• The rate of malignancy is low in polyps even 10 mm or larger (15.1 %).

Hepatobiliary phase of gadoxetic acid-enhanced MR in patients suspected of having gallbladder dyskinesia: comparison with hepatobiliary scintigraphy.

OBJECTIVE To compare hepatobiliary phase of gadoxetic acid-enhanced magnetic resonance (HMR) and hepatobiliary scintigraphy (HBS) for evaluation of cystic duct patency and gallbladder contractility in patients suspected of having gallbladder dyskinesia. MATERIALS AND METHODS Eighteen patients underwent HMR and HBS. Cystic duct patency and gallbladder ejection fraction (GBEF) were compared to determine a significant difference between HMR and HBS. RESULTS HMR and HBS had 15 concordant and 3 discordant results for cystic duct patency. GBEF in eight patients showed no significant difference between both modalities. CONCLUSION HMR may be an alternative to HBS for the functional evaluation of cystic duct patency and GBEF.

Extrahepatic Soft Tissue Mimicking Applicator-Tract Implantation After Percutaneous Radiofrequency Ablation of Hepatic Malignancy

OBJECTIVE The purpose of our study was to identify extrahepatic soft tissue mimicking applicator-tract implantation after percutaneous radiofrequency ablation of hepatic malignancy on triple-phase dynamic CT. MATERIALS AND METHODS A database was reviewed for 131 patients who underwent percutaneous radiofrequency ablation for treatment of a hepatic tumor over a 3-year period. Patients who developed extrahepatic soft tissue adjacent to the previous ablation zone mimicking applicator-tract implantation were identified. The clinical features of patients, characteristics of extrahepatic soft tissue on CT, soft-tissue changes on follow-up CT, and histopathologic results were evaluated. RESULTS Extrahepatic soft tissue developed in five patients (3.8%) at 2-8 months after percutaneous radiofrequency ablation. Extrahepatic soft tissue showed progressive enhancement during the delayed phase of dynamic CT. Four lesions were completely resolved without any treatment. However, one lesion was enlarged and xanthogranulomatous inflammation was diagnosed by percutaneous biopsy. Univariate analysis showed that an index tumor with a subcapsular location and a prior biopsy had high odds ratios. CONCLUSION The possibility of a benign inflammatory lesion should be considered when extrahepatic soft tissue showing radiologic findings similar to applicator-tract implantation develops after radiofrequency ablation of a hepatic tumor.