Taro Shimono

Clinically mild encephalitis/encephalopathy with a reversible splenial lesion

Objective: To clarify whether patients with clinical diagnoses of encephalitis/encephalopathy with a reversible lesion in the splenium of the corpus callosum (SCC) share common clinical features. Methods: Possible encephalitis/encephalopathy patients with a reversible isolated SCC lesion on MRI were collected retrospectively. Their clinical, laboratory, and radiologic data were reviewed. Results: Fifteen encephalitis/encephalopathy patients with a reversible isolated SCC lesion were identified among 22 patients referred for this study. All 15 patients had relatively mild clinical courses. Twelve of the 15 patients had disorders of consciousness. Eight patients had seizures, and three of them received antiepileptic drugs. All 15 patients clinically recovered completely within 1 month (8 patients within a week) after the onset of neurologic symptoms. The SCC lesion was ovoid in six patients; it extended irregularly from the center to the lateral portion of SCC in the other eight patients. Homogeneously reduced diffusion was seen in all seven patients who underwent diffusion-weighted imaging. There was no enhancement in the five patients so examined. The SCC lesion had completely disappeared in all patients at follow-up MRI exams between 3 days and 2 months after the initial MRI (within 1 week in eight patients). Conclusion: The clinical features among the affected patients were nearly identical, consisting of relatively mild CNS manifestations and complete recovery within 1 month.

Contrast Harmonic Sonography-Guided Radiofrequency Ablation Therapy Versus B-Mode Sonography in Hepatocellular Carcinoma: Prospective Randomized Controlled Trial

OBJECTIVE The purpose of this study was to evaluate the effectiveness of contrast harmonic sonographic guidance in radiofrequency ablation of locally progressive hepatocellular carcinoma poorly depicted with B-mode sonography. SUBJECTS AND METHODS A series of 40 patients with hepatocellular carcinoma with local tumor progression poorly depicted with B-mode sonography were randomly treated with radiofrequency ablation guided by either contrast harmonic sonography (n = 20) or conventional B-mode sonography (n = 20). Unpaired Students t tests were performed to compare numbers of treatment sessions. RESULTS Treatment analysis showed that the complete ablation rate after a single treatment session was significantly higher in the contrast harmonic sonography group than in the B-mode sonography group (94.7% vs 65.0%; p = 0.043) and that the number of treatment sessions was significantly lower in the contrast harmonic sonography group (mean, 1.1 +/- 0.2 vs 1.4 +/- 0.6; p =0.037). CONCLUSION Contrast harmonic sonography-guided radiofrequency ablation is an efficient technique for guiding further ablation of local tumor progression not clearly demarcated with B-mode sonography.

Transient splenial lesion of the corpus callosum associated with antiepileptic drugs: evaluation by diffusion-weighted MR imaging.

Abstract. Transient focal lesions in the splenium of the corpus callosum have been reported in epileptic patients receiving antiepileptic drugs. The characteristic imaging features included an oval high signal lesion on T2-weighted images in the central part of the splenium, no enhancement on post-contrast MR images, and complete reversibility without specific treatment. We report identical MR imaging findings in a depressive patient who had received antiepileptic drugs. In addition, diffusion-weighted MR imaging findings are described in our case, which is the first report on this unique lesion associated with antiepileptic drugs. Although this lesion has been assumed to be vasogenic edema in the previous reports, diffusion-weighted MR imaging showed markedly restricted diffusion of the lesion in the present case, suggesting that cytotoxic edema was the main pathophysiological abnormality.

Integrated FDG-PET/CT compared with intravenous contrast-enhanced CT for evaluation of metastatic regional lymph nodes in patients with resectable early stage esophageal cancer

ObjectiveTo assess whether integrated fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) can improve the diagnostic accuracy of metastatic regional lymph nodes (LNs) in esophageal cancer compared with contrast enhanced CT (CECT).MethodsWe examined 180 consecutive patients with esophageal cancer by integrated PET/CT between April 2006 and March 2007. Eighteen patients (M:F 14:4) underwent radical esophagectomy after evaluations by PET/CT and CECT of 5–7-mm-thick slices 70–80 s after injection. Regional LNs of esophageal cancer were retrospectively reviewed on CECT images by two blinded evaluators on the basis of the following cutoff sizes: 7 mm for all regional LNs (Protocol A), 10 mm for paratracheal LNs (Protocol B), and 7 mm for others. In addition, the maximum standardized uptake value (SUVmax) on PET/CT was evaluated for positive uptake by LNs.ResultsOf 210 LNs excised at surgery, 25 were positive and 185 were negative for metastasis at pathology. The PET/CT images identified 15 true-positive and 184 truenegative LNs, whereas CECT identified 15 true positives and 176 true negatives in Protocol A, and 14 true positives and 180 true negative in Protocol B. The sensitivity, specificity, accuracy, positive, and negative predictive values of PET/CT were respectively 60.0%, 99.5%, 94.8%, 93.8%, and 94.8%, whereas those of CECT were 60.0%, 95.1%, 91.0%, 62.5%, and 94.6% (Protocol A) and 56.0%, 97.3%, 92.4%, 73.7%, and 94.2% (Protocol B). A comparison of the two CECT protocols revealed fewer false-positive LNs in Protocol B, but slightly lower sensitivity in Protocol B than in Protocol A. Substantial numbers of false-positive LNs were determined by CECT in the paratracheal regions (6 of 9, 66.7%) and CECT revealed central necrosis in 4 of 15 (26.7%) true-positive LNs > 1.8 cm. The mean SUVmax on PET/CT was 2.9 (range 1.7–5.5) in true-positive LNs. The smallest LN metastasis detectable by PET/CT was 6 mm.ConclusionsIntegrated PET/CT improves the PPV of regional LNs when compared with CECT.

Comparison of short inversion time inversion recovery (STIR) and fat-saturated (chemsat) techniques for background fat intensity suppression in cervical and thoracic MR imaging.

The purpose of this study was to compare short inversion time inversion recovery (STIR) fast spin‐echo (FSE), and fat‐saturated T2‐weighted FSE sequences in terms of uniformity of fat suppression and lesion conspicuity for magnetic resonance (MR) imaging of the neck and thorax. STIR FSE and fat‐saturated T2‐weighted FSE images were scored for uniformity of fat suppression (n = 40) and lesion conspicuity (n = 35). Five‐point rank score analyses were utilized by three experienced radiologists. The mean scores of STIR and fat‐saturated FSE techniques for uniformity of fat suppression were 4.3 and 2.3, respectively (P < 0.0001). The mean scores of STIR and fat‐saturated FSE techniques for lesion conspicuity were 4.2 and 3.5, respectively (P < 0.0001). Insufficient fat suppression was prominent in the mandible, supraclavicular region, anterior mediastinum, epipericardial fat, and subdiaphragmatic fat. In addition, fat‐saturated T2‐weighted FSE showed inadvertent water suppression in 25%. The STIR FSE technique was superior to the fat‐saturated FSE technique for cervical and thoracic MR imaging. J. Magn. Reson. Imaging 2000;11:56–60.

Preoperative diagnosis of ovarian tumors, focusing on the solid area based on diagnostic imaging

Aim:  The objectives were to attempt to differentiate between benignancy and malignancy by focusing not on macroscopic finding of tumor sections, but on the solid areas by diagnostic imaging. To investigate the usefulness of diagnostic imaging for ovarian tumors, we examined the solid areas in the tumor and their shape and analyzed the relationship between these factors and the malignant potential.

Quantitative evaluation of norcholesterol scintigraphy, CT attenuation value, and chemical-shift MR imaging for characterizing adrenal adenomas

ObjectiveThe objective of our study was to evaluate diagnostic ability and features of quantitative indices of three modalities: uptake rate on norcholesterol scintigraphy, computed tomography (CT) attenuation value, and fat suppression on chemical-shift magnetic resonance imaging (MRI) for characterizing adrenal adenomas.MethodsImage findings of norcholesterol scintigraphy, CT, and MRI were reviewed for 78 patients with functioning (n = 48) or nonfunctioning (n = 30) adrenal masses. The norcholesterol uptake rate, attenuation value on unenhanced CT, and suppression on in-phase to opposed-phase MRI were measured for adrenal masses.ResultsThe norcholesterol uptake rate, CT attenuation value, and MR suppression index showed the sensitivity of 60%, 82%, and 100%, respectively, for functioning adenomas of <2.0 cm, and 96%, 79%, and 67%, respectively, for those of ≥2.0 cm. A statistically significant correlation was observed between size and norcholesterol uptake, and between CT attenuation value and MR suppression index. Regarding norcholesterol uptake, the adenoma-to-contralateral gland ratio was significantly higher in cortisol releasing than in aldosterone-releasing adenomas.ConclusionsThe norcholesterol uptake rate was reliable for characterization of adenomas among adrenal masses of ≥2.0 cm. CT attenuation value and MR suppression index were well correlated with each other, and were useful regardless of mass size.

T-staging of gastric cancer of air-filling multidetector-row CT: Comparison with hydro-multidetector-row CT

PURPOSE The purpose of this study was to evaluate the accuracy of T-staging of gastric cancer by air-filling multidetector-row CT (air-MDCT) compared with water-filling MDCT (hydro-MDCT). MATERIALS AND METHODS One hundred fifteen patients with histologically diagnosed gastric cancer were included in this study. Fifty-eight patients underwent air-MDCT, and the remaining 57 had hydro-MDCT using a 64-channel scanner. Based on the volumetric data of contrast-enhanced MDCT obtained about 75 s after intravenously injecting 525 mg iodine per kilogram patients weight (525 mgI/kg) nonionic contrast material at the rate of 2 ml/s, oblique coronal and oblique sagittal multi-planar reformatted images perpendicular to the stomach wall, including the tumor, were reconstructed on a workstation. Mural invasion of gastric cancer into the gastric wall, as visualized by CT, was classified according to the TNM classification, and the results of T-staging by MDCT were compared with those by pathologic analysis after surgery. RESULTS Correct assessment of T-staging by air-CT was achieved in 48 of 58 patients (83%), and that by hydro-MDCT was 49 of 57 patients (86%). The sensitivity, specificity, and accuracy of the technique in determining the invasion of serosa were 88%, 93%, and 91% for air-CT and 83%, 95%, and 91% for hydro-CT. There were no significant differences between hydro-MDCT and air-MDCT in sensitivity (P=0.73), specificity (P=0.71) and accuracy (P=0.98). CONCLUSION Air-MDCT is a very valuable tool in T-staging of gastric cancer as well as hydro-MDCT.

Acute bilateral medial medullary infarction: a unique 'heart appearance' sign by diffusion-weighted imaging.

Acute Bilateral Medial Medullary Infarction: A Unique ‘Heart Appearance’ Sign by Diffusion-Weighted Imaging Masayuki Maeda a, Taro Shimonob, Hirokazu Tsukahara c, Stephan E. Maierd, Kan Takeda a aDepartment of Radiology, Mie University School of Medicine, Mie, bDepartment of Radiology, Kinki University School of Medicine, Osaka, and cDepartment of Pediatrics, Fukui Medical University, Fukui, Japan; dDepartment of Radiology, Brigham and Women’s Hospital, Boston, Mass., USA

A case of TUBA1A mutation presenting with lissencephaly and Hirschsprung disease

Gene mutation of tubulin alpha-1A (TUBA1A), a critical component of microtubules of the cytoskeleton, impairs neural migration and causes lissencephaly (LIS). The approximately 45 cases of disease-associated TUBA1A mutations reported to date demonstrate a wide spectrum of phenotypes. Here we describe an 8-year-old girl with lissencephaly, microcephaly, and early-onset epileptic seizures associated with a novel mutation in the TUBA1A gene. The patient developed Hirschsprung disease and the syndrome of inappropriate antidiuretic hormone secretion (SIADH), which had not previously been described in TUBA1A mutation-associated disease. Our case provides new insight into the wide spectrum of disease phenotypes associated with TUBA1A mutation.