Shigeru Mitsuka

Discrepancies in brain perfusion SPECT findings between Tc-99m HMPAO and Tc-99m ECD: evaluation using dynamic SPECT in patients with hyperemia.

Discrepancies have been reported between the findings of Tc-99m HMPAO and Tc-99m ECD brain perfusion SPECT imaging. This study investigated the discrepancies in the accumulation of these tracers using dynamic SPECT to detect the super early phase of distribution. Thirteen patients with luxury perfusion or high flow states were studied with both dynamic and standard SPECT using Tc-99m HMPAO and Tc-99m ECD within 1-3 days. Standard SPECT showed discrepancies in 6 of 13 patients. Patients with meningioma and cerebral thrombosis had increased accumulation of Tc-99m HMPAO and decreased uptake of Tc-99m ECD. Patients with arteriovenous malformation, subarachnoid hemorrhage, and cavernous angioma had decreased accumulation of both tracers, but to different degrees. Dynamic SPECT showed increased or normal accumulation (i.e., essentially no discrepancy) in the first few minutes. However, Tc-99m HMPAO had a longer retention time than Tc-99m ECD in the ensuing 5-10 minutes. Dynamic SPECT revealed a similar accumulation pattern but different washout rates for the two tracers. Tc-99m HMPAO might be a more suitable tracer to detect high flow states or luxury perfusion because the findings on standard SPECT were more in agreement with those of dynamic SPECT using this tracer.

Long-term observations in cases with spontaneous carotid-cavernous fistulas

Twenty-six cases with spontaneous carotid-cavernous fistulas were followed up for periods ranging between 4 months and 9 years 8 months. A complete regression of symptoms without reappearance for more than 6 months was noted in 19 cases, a marked improvement in 2 cases, and a moderate regression in 3 cases. In 2 cases, symptoms have continued for 9 years 8 months and for 1 year. The regression of symptoms was usually delayed in patients less than 60 years old, in cases in which the symptoms developed slowly, and in cases with multiple draining veins. According to our observations a regression of symptoms may occur after very slight changes of haemodynamics. Compression of the cervical carotid artery for a short time or a temporary occlusion of the carotid artery by a balloon catheter should be considered as the treatment of choice in the first instance in cases with spontaneous carotid-cavernous fistulas showing relatively low pressure and low flow shunt.

Surgical Treatment of Multiple Aneurysms

The authors reviewed surgical results of 618 surgically treated patients with intracranial aneurysms. Multiple aneurysms were observed in 106 (20%) patients. In cases of multiple aneurysms, their policy has been to treat all aneurysms, ruptured and unruptured, in a one-stage operation whenever possible. All aneurysms of 92 patients were treated in one-stage operations. Eighty three (90%) patients improved or remained stationary, 6 (7%) deteriorated, 3 (3%) died postoperatively. The cause of deterioration or death were due to cerebral vasospasm, primary brain damage or surgical procedure for ruptured aneurysms. No significant difference was found in comparing the rupture site of the aneurysm or the timing of the operation in each preoperative clinical grade. Furthermore, all patients were classified into three groups according to the location of the aneurysms. Sixty-two patients had unilateral aneurysms including aneurysms in the midline, i.e. anterior communicating artery aneurysms, distal basilar artery aneurysms and/or bilateral pericallosal artery aneurysms (unilateral group), and 30 patients had bilateral aneurysms (bilateral group). Morbidity and mortality in unilateral group was 6% and 3%, while in bilateral group, 7%, 3% respectively. No significant difference was observed in the bilateral group compared with the unilateral group, and surgical results of each group appeared to be satisfactory. Neither death nor deterioration was found attributable to operative procedure when unruptured aneurysms were added to the surgery for ruptured aneurysms in a one-stage operation. These surgical results for 92 cases were similar to the results in the rest of the 526 cases. Based on these results, the one-stage operation is recommended, whenever possible, for patients with multiple aneurysms, even if bilateral craniotomy is needed.

Quantitative Autoradiographical Evaluation of Protein Synthesis in a Brain Tumor Model Using 14C-labeled Valine

Since tumor tissue grows rapidly, it can be assumed that a large amount of protein has to be synthesized in the tissue. Previous studies have already shown evidence that a very high exogenous uptake of amino acid is present in human brain tumor [1,2]. The studies were done by positron emission tomography (PET) using 11C-DL-valine, 11C-DL-tryptophan [1], and L-11C-methionine [2]. An autoradiographical method for the measurement of the rate of protein synthesis has also been introduced [3,4]. A variation of this method has been applied to some experimental brain tumors as well [5]. The kinetic model for L-1-14C- leucine incorporation into proteins, described by Smith et al. [3], was applied to L-1-14C-valine, and the rate constants were measured in several normal brain structures [6]. In this paper, we describe the measurement of the rate constants and the rate of valine incorporation into proteins in AA ascites tumors implanted into rat brains. The reliability and the applicability of the kinetic model to the tumor model is also discussed.