Difference between T1 and T2 weighted MR images in avascular necrosis of the femoral head

T1 and T2 weighted MR images were compared in 32 hips with avascular necrosis, and the difference between them was discussed. In 27 of 32 hips, abnormal low intensity area in the affected femoral head is smaller in T2 weighted images than in T1 weighted images. The area of low intensity on T1 weighted image and high on T2 weighted image might be granuloma in reactive tissue and surrounding hyperemia. The difference between T1 and T2 weighted images must be taken into consideration especially in determination of the border of affected bone.     

Radiotherapy of metastatic bone tumor with a synthetic calcitonin derivative (Elcatonin) with irradiation

Twenty cases of metastatic bone tumors were treated with Elcatonin together with irradiation, achieving pain relief in 47.3% of cases, improved bone scintigrams in 16.7% of cases and radiographic improvement of invaded bone in 7.7% of cases. It has reported that calcitonin is effective for pain relief in 50% of cases but for the radiographic improvement of bone lesions in only 0-10%. The life quality of patients with bone metastases is controversial since treatment techniques for advanced oncological patients has progressed remarkably. The pain relief obtained with calcitonin contributes significantly to improving the quality of life for such patients when administered in combination with conventional treatment modes.     

Binding cells of125I-iodoamphetamine in rat liver

We recently reported that transrectal or intestinal portal scintigraphy with¹²³I-iodoamphetamine (IMP) could be a useful method for the non-invasive and quantitative evaluation of the portosystemic shunt in portal hypertension, but what cells in the liver trap IMP has not been clarified. This study was aimed at elucidating whether IMP was extracted by parenchymal cells, sinusoidal endothelial cells, Kupffer cells or fat storing cells. Each type of liver cell was isolated from rats and cultured. The cells were incubated with¹²⁵I-IMP and the radioactivity of the lysate was determined. Nonspecific binding was assessed in the presence of an excess of unlabeled IMP, and specific binding was determined by subtracting the nonspecific from total binding. Specific binding observed in parenchymal cells, endothelial cells and Kupffer cells was 70.2 ± 0.4, 4.2 ± 1.4 and 2.3 ±0.8 pmol/well, respectively, but no specific binding was observed in fat storing cells. The binding in parenchymal cells was much higher than that in endothelial cells or Kupffer cells (p < 0.005). In addition, the binding to parenchymal cells reached equilibrium within 20 min and was not saturable over the concentration range tested (0.5–10 μM). These findings indicate that IMP is mostly extracted by parenchymal cells in the liver.     

Solitary renal hamartoma not associated with tuberous sclerosis: roles of CT and angiography

CT and angiography of five solitary renal hamartomas not associated with tuberous sclerosis are reviewed. CT revealed fat in four hamartomas and was the more reliable in the differentiation from renal cancer. Bleeding from the tumour was detected in two cases and the extent of each haematoma was precisely determined by CT. Angiography showed specific findings in only one tumour. In a pararenal hamartoma, angiography was of value in clarifying the renal origin of the tumour. Though angiography may be of help when CT is inconclusive, we think it should not be relied upon as a major diagnostic tool and we utilise it mainly for preoperative mapping and embolisation. In one case CT did not detect fat and preoperative diagnosis was impossible. In one case with haematoma, detection of fat was difficult. We believe potential hamartomas with no detectable fat should be treated as malignancy until proved otherwise. There seems to be discrepancy between the vascularity of the hamartoma and the degree of contrast enhancement (CE) with a bolus injection method; hamartomas seem to show weaker CE than that expected for renal cancer of equal vascularity, a fact which may differentiate solitary hamartoma from cancer.     

Synthesis of pyruvate-1-11C as a radiopharmaceutical for tumor imaging

Pyruvate-1-11C was prepared enzymatically by the exchange reaction of 11CO2 with the carboxyl group of pyruvic acid using pyruvate-ferredoxin oxidoreductase from Clostridium butyricum. 11C-Labeled pyruvate was purified by sublimation in specially made glassware. The radiochemical yield of pure pyruvate-1-11C was 80% 35 min after the end of bombardment. The distribution of 11C in tumor-bearing rabbits after an i.v. injection of pyruvate-1-11C was observed using a gamma camera. In contrast to normal organs, the tumor was positively visualized. We also conducted a number of successful clinical studies. A case of brain tumor which exhibited a positive image on positron-emission tomography (PET) using pyruvate-1-11C is presented.     

The value of the modified high temporal resolution phase analysis for the detection of myocardial infarction

Recently, cardiac nuclear medicine, especially gated RI cardiac blood pool scan has been improved remarkably, and now phase analysis has been introduced. We have developed a new modified phase image, with the objective of improving the time resolution, by displaying a special range of phase angles (about pi/3 radian) with 16 color scales, which correspond to the ventricles. Compared with the conventional method, the high resolution phase image improved the sensitivity of diagnosis of the region of myocardial infarction. The sensitivity of the modified phase image was 91% (10 cases our of 11), whereas that of the conventional method was 27% (3 cases out of 11).     

Visualization of cerebellopontine angle diseases by nuclear magnetic resonance imaging

The preliminary results from the clinical use a prototype whole body nuclear magnetic resonance (NMR) machine constructed by Toshiba Inc. are presented. Cranial NMR scans were performed on more than 30 cases with broad spectrum of neurologic diseases using saturation-recovery and inversion-recovery sequences with a field strength of 1500 Gauss. Selective excitation sequence was used for the slice selection and filtered backprojection was used to reconstruct the images. They were displayed on a 256 X 256 matrix as 12 mm thick sections. Data acquisition time varied between 3 and 12 minutes. Our initial experiences with six cases harboring cerebellopontine angle lesions disclosed advantages and disadvantages of NMR imaging in comparison with X-ray CT. The advantages were the absence of linear artifacts from the surrounding bone, the marked gray-white matter differentiation, and the variety of tomographic planes available. The disadvantages included the lack of bone detail, the lack of visualization of the major intracranial vessels, and the long time required for scanning (several minutes per slice). Although much continued evaluation is necessary, NMR seems to have vast potential as a diagnostic tool.