MR appearances of radiofrequency thermal ablation region: histopathologic correlation with dog liver models and an autopsy case

RATIONALE AND OBJECTIVES: The purpose of this study was to evaluate the utility of magnetic resonance (MR) imaging for indicating the extent of true tissue necrosis of the liver after radiofrequency (RF) ablation in comparison with histopathologic findings in dog models and an autopsy case. MATERIALS AND METHODS: RF ablation of the liver parenchyma was performed on three dogs under general anesthesia. MR appearances of the RF-ablated regions on T1-weighted fast-low angle shot (FLASH; repetition time/echo time [TR/TE]/flip angle: 120/3.8/70),T2-weighted turbo spin echo (3000/80/echo train = 25) and contrast-enhanced T1-weighted images were compared with histopathologic findings. An autopsy case with hepatocellular carcinoma was also enrolled in this study. RESULTS: All ablated regions showed three zones on T1-weighted FLASH images: a central zone with low intensity, a broad hyperintense middle zone, and a surrounding hypointense band. The central and middle zones corresponded to the degrees of coagulation necrosis observed during histopathologic examination, whereas no viable cells were seen in these zones during the microscopic examination using nicotinamide adenine dinucleotide diaphorase stain. The surrounding hypointense band corresponded to sinusoidal congestion in the acute phase and to fibrotic change in the subacute phase. CONCLUSION: MR imaging using the FLASH sequence can accurately determine the extent of the necrotic area after RF ablation.     

The usefulness of radio-guided surgery in secondary hyperparathyroidism

Recent reports have shown that radio-guided surgery with an intraoperative gamma probe (IGP) is useful for identifying parathyroid adenomas. The aim of this study was to evaluate the usefulness of IGP mapping in patients with secondary hyperparathyroidism. Seven patients with secondary hyperparathyroidism underwent technetium-99m methoxyisobutylisonitrile (Tc-99m MIBI) scintigraphy immediately before undergoing surgical resection of all parathyroid tissues. We compared the sensitivity of Tc-99m MIBI scintigraphy alone with that of the combination of Tc-99m MIBI scintigraphy and IGP mapping. The sensitivity of the combination of Tc-99m MIBI scintigraphy and IGP mapping was 100% (28 of 28 lesions) and was significantly higher than that of Tc-99m MIBI scintigraphy alone (71.4%, 20 of 28 lesions). The combination of the Tc-99m MIBI scintigraphy and IGP mapping has increased sensitivity for identifying parathyroid lesions during parathyroidectomy in patients with secondary hyperparathyroidism.     

Acute cerebral infarction: effect of JPEG compression on detection at CT

PURPOSE: To evaluate the effect of Joint Photographic Experts Group (JPEG) compression ratios of 10:1 and 20:1 on detection of acute cerebral infarction at computed tomography (CT). MATERIALS AND METHODS: CT images obtained in 25 patients with acute cerebral infarction and 25 patients with no lesions were compressed by means of a JPEG algorithm at ratios of 10:1 and 20:1. Normal and abnormal sections (on original and compressed images) were reviewed by using a color soft-copy computed monochrome cathode ray tube monitor. Five observers rated the presence or absence of a lesion with a 50-point scale (0, definitely absent; 25, equivocal; and 50, definitely present). Diagnostic accuracy was evaluated with receiver operating characteristic (ROC) curve analysis. Significant difference was defined as a P value less than.05 for the area tested with a two-tailed paired Student t test. RESULTS: At ROC analysis, no statistically significant difference was detected for all cases considered together (Az [area under the ROC curve] = 0.887 +/- 0.038 [mean +/- SD] on noncompressed images, Az = 0.897 +/- 0.038 on 10:1 compressed images, and Az = 0.842 +/- 0.073 on 20:1 compressed images; P >.05). CONCLUSION: JPEG compression at ratios of 10:1 and 20:1 was tolerated in the detection of acute cerebral infarction at CT.     

A case of atypical type A thymoma with vascular invasion and lung metastasis

We present a case of type A thymoma with invasion of the left brachiocephalic vein and lung metastases. An 84-year-old man underwent extended thymectomy combined with left brachiocephalic vein reconstruction and resection of a lung metastasis. Histological examination showed vascular invasion by the tumor. The lung metastasis had high mitotic activity and slight nuclear enlargement, the so-called “atypical” features, but the main part of the primary tumor did not. However, the intravascular portion of the tumor had “atypical” histological features like the lung metastasis. It seems that “atypical” histological features are related to clinically malignant behavior.     

Intradural extramedullary hemangioblastoma differentiated by MR images in the cervical spine: a case report and review of the literature

We report a rare case of hemangioblastoma existing in the intradural extramedullary location diagnosed by magnetic resonance imaging (MRI) examination alone. A 46-year-old man gradually developed numbness in his lower extremities. MR images revealed a tumor shadow located posterior to the spinal cord at C5-C7. Small signal void shadows were continuously observed from C1 to C5 in the region cranial to the tumor, indicating the presence of enlarged vessels. Under microscopic observation, the tumor with accompanying vessels was resected totally via hemilaminectomy. The postoperative course was uneventful, and MR images obtained 4 months after the operative procedure demonstrated total removal of the tumor and the abnormal vessels. In this case, recognizing the abnormally enlarged vessels outside the tumor mass preoperatively led us to the correct diagnosis on MR images.     

Postoperative changes in mandibular prognathism surgically treated by intraoral vertical ramus osteotomy

This study investigated short- and long-term postoperative skeletal changes following intraoral vertical ramus osteotomy (IVRO) for mandibular prognathism, as determined from lateral cephalograms. The subjects were 20 patients with mandibular prognathism who had undergone surgical orthodontic treatment combined with IVRO. Lateral cephalograms were taken at six time points: 1 month before surgery, and 1 day, 3 months, 6 months, 1 year, and approximately 2 years after surgery. Intermaxillary fixation (IMF) with four monocortical screws was maintained for 1 week in all patients. Mean posterior movement of the menton (Me) was 5.9 mm at surgery. 3 months after surgery, the FMA and FH-CorMe angles had increased 6.3 and 6.2 degrees, respectively, indicating clockwise rotation of the distal segment of the mandible. This rotation was observed in all 20 patients, suggesting that postoperative rotation of the mandible in the postoperative short term is likely to occur after IVRO and could be considered an adaptation of the mastication system newly established by surgery. In the long term after IVRO, Me had moved anteriorly by only 0.9 mm and the relapse ratio was 15.3%. These findings suggest the excellent long-term stability of surgical orthodontic treatment combined with IVRO in patients with mandibular prognathism.     

Effects of sex hormones on induction of intestinal metaplasia by X-irradiation in rats.

The influence of sex hormones on induction of intestinal rnetaplasia was examined in 5 week old Crj: CD (SD) rats of both sexes. At the age of 4 weeks, the animals were gonadectornized and given testosterone or dimethyl estradiol (DES). One week after operation, they were irradiated with two 10 Gy doses of X-rays to the gastric region at a 3 day interval for a total of 20 Gy. At the termination of the experiment, 6 months after the X-irradiation, the incidence of intestinal metaplasia with alkaline phosphatase (ALP) positive foci in males was significantly higher than in females, in orchidectomized males or orchidectomized plus DES treated rats (P <0.01). On the other hand, the incidence of intestinal metaplasia with ALPpositive foci in normal females appeared lower than in ovariectomized females (P < 0.01), and was increased in rats by treatment with testosterone or decreased by DES. Numbers of foci of intestinal metaplasias with Paneth cells and total numbers appeared to increase in males treated with DES. The results suggested a promoting role for testosterone in the development of ALP positive lesions and indicated considerable heterogeneity between intestinal metaplasia subtypes.     

The clinical outcomes and the ability to sit straight in the Japanese style following high tibial osteotomy combined with osteochondral autologous transfer for osteonecrosis of the medial femoral condyle

Background

There have been some reports of high tibial osteotomy combined with osteochondral autograft transfer for osteonecrosis of the medial femoral condyle of the knee. However, few of them have focused on the deep knee flexion needed to sit straight in the Japanese style.

Laparoscopic resection of periadrenal paraganglioma in a patient with multiple endocrine neoplasia type 2A

We report here a case of recurrent pheochromocytoma successfully managed by laparoscopic surgery in a patient with multiple endocrine neoplasia type 2A. A 25-year-old man presented with the contralateral adrenal mass after earlier right adrenalectomy. For the preoperative diagnosis of left adrenal pheochromocytoma, adrenal sparing surgery was considered. From the intraoperative laparoscopic view, we found that the tumor originated in periadrenal sympathetic ganglia, and laparoscopic excision of paraganglioma was successfully performed that preserved the integrity of normal adrenal gland. Extra-adrenal pheochromocytoma is rather rare in MEN 2A and it is important to identify precise intraoperative localization of pheochromocytoma with laparoscopic surgery.