Nobushige Hayashi

Intravoxel incoherent motion(IVIM)MRI in intracranial, extraaxial tumors and cysts

Intravoxel incoherent motion MRI was used to assess ix intracranial, extraaxial cysts and tumors including two epidermoids, two cystic acoustic schwannomas, and two arachnoid cysts. A maximum gradient strength of 0.7 g/cm was used simultaneously along all axes (maximum gradient b value: 445 s/mm2) and comparisons were made with an external water phantom. In epidermoid tumors the apparent diffusion coefficient (ADC) was similar to that of normal brain, thus indicating their solid nature. In acoustic schwannomas an ADC similar to the external water phantom indicated cystic components, whereas an ADC similar to brain was found in the solid portions of the tumor. The ADC of arachnoid cysts was similar to that of the water phantom, indicating their fluid nature. Due to macroscopic CSF flow, cisternal CSF showed high ADC, which enabled epidermoid tumors to be highlighted.

Radiation exposure to interventional radiologists during manual-injection digital subtraction angiography

Purpose: We investigated the relationship between the amount of radiation exposure to the operator during tableside manual-injection angiographic procedures including digital subtraction angiography (DSA) and the operator’s position, as well as a simple means to decrease radiation exposure.Methods: Measurement of radiation exposure was carried out with thermoluminescent dosimeters (TLDs) in nine abdominal angiographies. In the first study, radiation exposure during DSA or during fluoroscopy was measured using TLDs placed near the angiographic table. In the second study, radiation exposure to the interventional radiologist was measured during manual-injection DSA at a near and a far operator position.Results: Radiation exposure to the operator received during manual-injection DSA accounted for more than 90% of the total procedural exposure. The exposure to the operator markedly decreased at the far position compared with that at the near position when performing DSA.Conclusion: Manual-injection DSA is the largest contributor to radiation exposure received by the interventional radiologist, therefore, the use of a power injector is always recommended when performing DSA. When manual-injection DSA is necessary, radiologists should position themselves as far away from the patient as possible.

Suppression of heat-induced HSF activation by CDDP in human glioblastoma cells

PURPOSE The kinetics of the accumulation of inducible 72-kD heat shock protein (hsp72) and the activation of heat shock transcriptional factor (HSF) after hyperthermia and/or CDDP treatment in two human glioblastoma cell lines, A-172 having the wild-type p53 gene and T98G having the mutated p53 gene were evaluated. METHODS AND MATERIALS Western blot analysis of hsp72, gel-mobility shift assay of HSF, cell survival, and development of thermotolerance were examined. RESULTS The prominent suppression of heat-induced hsp72 accumulation by CDDP was seen in A-172 cells, but not in T98G cells. This was due to the p53-dependent inhibition of heat-induced HSF activation by CDDP. The interactive hyperthermic enhancement of CDDP cytotoxicity was observed in A-172 cells, but not in T98G cells. In addition, the heat-induced thermotolerance was suppressed by the presence of CDDP in the pretreatment. CONCLUSION Suppression of heat-induced hsp72 accumulation by CDDP contributes to an interactive hyperthermic enhancement of CDDP cytotoxicity in the cells bearing the wild-type p53 gene.

Alterations of lactate (+lipid) concentration in brain tumors with in vivo hydrogen magnetic resonance spectroscopy during radiotherapy.

RATIONALE AND OBJECTIVES The authors determine whether assessment of the relative lactate(+lipid) concentration ([r-Lac(+lip)]) obtained from hydrogen magnetic resonance (MR) spectroscopy is useful for predicting the outcome of radiotherapy on brain tumors. METHODS Fifty-one hydrogen MR spectroscopic studies were performed in eight patients with primary or metastatic brain tumor before and during radiotherapy. The r-Lac(+lip) calculated as the ratio of lactate(+lipid) peak area to total water was compared before and during radiotherapy in each case. The change of tumor volume measured on magnetic resonance images also was compared. RESULTS The r-Lac(+lip) substantially decreased in the radiosensitive cases (three lymphomas and one brain cancer) but did not decrease, even at the end of therapy, in the radioresistant cases (two brain cancers and two glioblastomas). CONCLUSION Assessment of r-Lac(+lip) may adjunctively contribute to the early prediction of the radiotherapeutic effect on brain tumors.

Percutaneous long-term arterial access with implantable ports: Direct subclavian approach with US

PURPOSE To clarify the clinical feasibility of getting a long-term arterial access at the subclavian region by directly puncturing the artery under ultrasound guidance. MATERIALS AND METHODS Percutaneous placements of arterial infusion catheters with implantable ports were performed in 30 patients with malignant abdominal tumors. The axillary artery in the subclavian region was punctured directly with an 18G needle under ultrasound guidance. Using the Seldinger technique, a 5Fr catheter was placed with its tip in the hepatic or the other tumor-supplying arteries. The catheter was connected to an implantable port, and both of them were embedded in the subcutaneous pocket. RESULTS Percutaneous placements of infusion catheters were successfully performed in 29 cases. Transarterial chemotherapy through implanted ports was done uneventfully in 26 patients, while in the other three cases, catheter dislodgment occurred. Two local haematomas, one wound infection and one cerebellar infarction were also experienced. CONCLUSION Ultrasound-guided subclavian approach is a minimally invasive way of implanting an infusion catheter for chemotherapy, although its indication for severely atherosclerotic patients should be limited.

Technegas ventilation SPECT for evaluating silicosis in comparison with computed tomography

To compare the subtle pulmonary parenchymal morphologic changes with ventilation function in patients with silicosis, the conventional CT, high resolution CT and technegas ventilation SPECT were performed. In 25 silicotic patients and six controls, the pulmonary ventilation state was evaluated by an index called the coefficient of variation (CV), which expresses the subliminal heterogeneous distribution of technegas in the lungs. The results showed that with silicosis the CV value is significantly higher than that without silicosis. The CV value was proved by multifactorial analysis to independently reflect the extent of the appearance of small scattered interstitial findings such as nodules, septal thickening and bulla, which were typical findings for silicosis. The CV value calculated from the technegas SPECT correlated well with the severity of silicosis. It is considered that the CV value can also express the functional state of the silicotic lung.

Application of a self-expanding metallic stent to a strictured esophagojejunostomy

We placed a Gianturco self-expanding metallic stent across the recurrent stricture of an esophagojejunostomy in a patient with gastric cancer. Though excellent passage of food resulted, intractable reflux occurred. Two months later the patient succumbed to recurrent tumor. At autopsy, the stent was patent and was partially covered by esophageal mucosa. There were narrow but deep ulcers around the stent hooks. The Gianturco metallic stent may provide an additional option for treating recurrent enteric strictures after other methods fail. Further refinements of the technique appear necessary.

Clinical value of triple-energy window scatter correction in simultaneous dual-isotope single-photon emission tomography with123I-BMIPP and201TI

To improve the image quality in simultaneous dual-isotope single-photon emission tomography (SPET) with iodine-123 labelled 15-(p-iodophenyl)-3-methylpentadecanoic acid (BMIPP) and thallium-201, we applied the triple-energy window method JEW) for correction of the cross-talk and scatter artifact. Seventy-one patients with coronary artery disease were included.201T1 cross-talk into the123I acquisition window (group 1,n = 30) and123I cross-talk into the201Tl window (group 2,n = 41) were studied. In group 1,123I images were first obtained (single-isotope images), followed by201Tl injection and SPET acquisition using dual-isotope windows (dual-isotope images). In group 2, the order was reversed. The dual-isotope SPET images with and without TEW were compared with the single-isotope images. Qualitative evaluation was performed by scoring the segmental defect pattern. Detectability of the mismatched fatty acid metabolism on dual-isotope SPET was evaluated by receiver operating characteristic (ROC) curve analysis. Segmental defect pattern agreement between dual and corrected single images was significantly improved by TEW correction (P<0.01). The agreement was particularly improved in segments with absence of uptake. There was no significant difference between TEW-corrected dual-isotope SPET and corresponding single-isotope SPET with regard to either % defect count or background activity. Mismatched fatty acid metabolism depicted by dual-isotope SPET predicted abnormal wall motion more accurately with TEW than without TEW. With TEW, a practical method for scatter and cross-talk correction in clinical settings, simultaneous dual123I-BMIPP/201Tl SPET is feasible for the assessment of myocardial perfusion/metabolism mismatch.

Real-time sonography of palpable breast masses.

In order to evaluate the clinical usefulness of an electronic real-time linear array scanner in breast diseases, ultrasonography was performed in 148 cases of histologically confirmed palpable breast masses. The real-time images were observed on a television monitor while moving the hand-held transducer probes over the masses. It took only a few minutes to examine and diagnose a palpable mass. Among 45 carcinomas, 39 lesions were correctly diagnosed, four lesions were not detected by ultrasound and two were misdiagnosed as fibroadenomas. On the other hand, ten benign lesions were falsely diagnosed as breast cancers: seven mastopathies (including four sclerosing adenosis), two fibroadenomas and one abscess. The sensitivity and specificity for diagnosing breast cancer were 0.87 and 0.90 respectively. Real-time sonography is a simple, time-saving and useful tool for examining palpable breast masses. However, it should be realised that some breast cancers are difficult to image and differentiate from benign lesions.

Nonlinear Geometric Warping of the Mask Image: A New Method for Reducing Misregistration Artifacts in Digital Subtraction Angiography

AbstractPurpose: Misregistration artifact is the major cause of image degradation in digital subtraction angiography (DSA). The purpose of this study was to evaluate the efficacy of a newly developed nonlinear geometric warping method to reduce misregistration artifact in DSA. Methods: The processing of the images was carried out on a workstation with a fully automatic computerized program. After making differential images with a lapracian filter, 49 regions of interest (ROIs) were set in the image to be processed. Each ROI of the live image scanned the corresponding ROI of the mask image searching for the best position to match itself. Each pixel of the mask image was shifted individually following the data calculated from the shifts of the ROIs. Five radiologists compared the images produced by the conventional parallel shift technique and those processed with this new method in 16 series of cerebral DSA. Results: In 14 of 16 series (88%), more radiologists judged the images processed with the new method to be better in quality. Small arteries near the skull base and veins of low density were clearly visualized in the images processed by the new method. Conclusion: This newly proposed method could be a simple and practical way to automatically reduce misregistration artifacts in DSA.