Nobuyoshi Ishikawa

The functional hepatic volume assessed by99mTc-GSA hepatic scintigraphy

The accuracy of measurement of the functional hepatic volume by single photon emission computed tomography (SPECT) with99mTc-galactosyl serum albumin (99mTc-GSA) was evaluated.99mTc-GSA planar scintigraphic images were obtained dynamically and the hepatic SPECT imaging was then performed in 25 patients with hepatobiliary tumors. The patients were divided into 4 groups with normal hepatic function, and mild, moderate and severe hepatic dysfunction. The functional hepatic volume determined by SPECT was compared with the morphological hepatic volume determined by computed tomography. The ratio of the hepatic volumes obtained by the two methods was calculated. The mean hepatic volume ratio was 96.6 ± 2.3% in the normal hepatic function group and 95.9 ± 2.2% in the mild dysfunction group (n.s.). In both the moderate and severe hepatic dysfunction groups, the hepatic volume ratio was smaller than that in the normal group (87.9 ±5.2%, p < 0.001, and 71.9 ± 7.6%, p < 0.0001, respectively). There was a linear correlation between the hepatic volume ratio and various indices of reserve hepatic function, such as LHL15 (r = 0.83, p < 0.0001), HH15 (r = 0.74, p < 0.0001), and ICG15 (r = 0.75, p < 0.0005). These results indicate that the hepatic volume ratio is proportional to the severity of hepatic dysfunction, and suggest that the functional hepatic volume measured with99mTc-GSA faithfully reflects the functioning hepatocyte mass.99mTc-GSA scintigraphy and hepatic SPECT therefore provide information regarding global and regional reserve hepatic function.

N-isopropyl-p-[123I]iodoamphetamine SPECT in MELAS syndrome: comparison with CT and MR imaging.

Regional cerebral perfusion was studied in three patients with the mitochondrial encephalomyopathy with lactic acidosis and stroke-like episodes (MELAS) syndrome, using single photon emission computed tomography (SPECT) with N-isopropyl-p-[123I]iodoamphetamine (IMP). Accumulation of the tracer was relatively decreased in the parietooccipital regions and also in the frontotemporal regions after stroke-like episodes. However, quantitative regional cerebral blood flow (rCBF) measurement showed that rCBF was relatively well preserved even at these sites, and a hyperemic state was observed at the sites of normal accumulation. IMP SPECT may be useful in the diagnosis and assessment of the progress of the MELAS syndrome.

Radioiodinated Metaiodo-benzylguanidine Scintigraphγ for Pheochromocytoma

Radioiodinated metaiodobenzylguanidine (MIBG) scintigraphy is known for its high specificity in detecting pheochromocytoma and other tumors of neural crest origin. We describe herein the first case of

Quantitative phase analysis of myocardial wall thickening by technetium-99m 2-methoxy-isobutyl-isonitrile SPECT

Regional wall thickening was assessed by ECG-gated SPECT using technetium-99m 2-methoxy-isobutyl-isonitrile (99mTc-MIBI). For myocardial segments with an optimal short axis, regional count changes from end-diastole to end-systole were used to calculate the regional wall thickening. Functional images displaying amplitude, % wall thickening (% WT), and phase were generated by a fundamental Fourier analysis. In the control subjects, % WT analysis showed heterogeneous contraction among the left ventricular wall segments. The amplitude values showed a similar pattern to the %WT values. Phase images demonstrated that the timing of ventricular contraction was almost homogenous between the various wall segments. In the CAD patients, regional decreases in amplitude and %WT corresponding to zones of reduced perfusion were shown in the ischemic segments. Phase images also indicated asynchronous contraction in these segments. Phase analysis of regional wall thickening in 99mTc-MIBI scintigraphy seems to be useful for understanding regional myocardial function in combination with perfusion scanning.

Study on the primary visual cortex of visually impaired subjects by means of123I-IMP SPECT and MRI

We conducted a study of rCBF in the primary visual cortex of visually impaired subjects who have not been subjected to external stimulation for a long period, by means of123I-IMP SPECT and MRI. The four subjects had lost their sight due to brain tumors (n = 2), glaucoma (n = 1) and trauma (n = 1).123I-DVIP SPECT showed no differences between the visually impaired group and a visually sound control group on visual analysis as well as semiquantitative analysis. MRI of the visually impaired subjects showed no organic changes, such as atrophy, in the occipital cortex.In conclusion, visually impaired subjects have no decrease in rCBF and no anatomical changes in the primary visual cortex.

Epilepsy accompanied by intracranial arachnoid cysts: studies on volume and regional cerebral blood perfusion using MRI and SPECT

Abstract To evaluate whether arachnoid cysts (ACs) can directly cause epilepsy by cortical compression, we studied the relationships among seizures, the volume of ACs, and regional cerebral blood perfusion around ACs. Subjects were 11 patients (10.5 ± 7.2 years) with primary intracranial ACs. The AC volume was calculated from axial T 1 -weighted magnetic resonance imaging (MRI). N-isopropyl p-iodoamphetamine ( 123 I-IMP) single photon emission computed tomography (SPECT) was used to evaluate cerebral blood perfusion. The lesional side to normal side ratio (L/N ratio) was calculated from rectangular and irregular region of interests (ROIs) in frontal and temporal area around the ACs. The volume of ACs in nonepileptic patients was significantly larger than in epileptic patients. In nonepileptic patients, SPECT demonstrated hyperperfusion around ACs, whereas in epileptic patients it showed hypoperfusion. The L/N ratio of rectangular ROIs in the posterior temporal area and irregular ROIs in the temporal area were significantly lower in epileptic patients than in nonepileptic ones. Our results suggest that epilepsy with ACs is related to the cerebral blood perfusion in the surrounding brain structures rather than to the volume of the ACs. Not only compression but also complicated brain parenchymal lesions may participate in the development of epilepsy.

A giant tumor thrombus in the right atrium clearly detected by 111In-oxine labeled platelet scintigraphy

A 54-year-old man was admitted to hospital with a 3-month history of progressive dyspnea with coughing. A giant right atrial mass, originating from a hepatocellular carcinoma, was visualized by computed tomography, and digital subtration angiography. The volume of the right atrial mass was increasing rapidly. It was therefore essential to determine whether this giant mass was a tumor thrombus or a multiplication of the hepatocellular carcinoma. 111In-oxine labeled platelet scintigraphy revealed active accumulation in the right atrium caused by the presence of active platelet deposition, and slight accumulation in the lung fields probably due to embolic showers originating from the tumor thrombus in the right atrium. This is the first case report showing that 111In-oxine labeled platelet scintigraphy can aid in confirming the nature of a giant tumor thrombus in the right atrium and can clarify the pathogenesis of the respiratory symptoms.

A study of ventricular contraction sequence in complete right bundle branch block by phase analysis

Twenty-four patients with complete right bundle branch block (CRBBB) combined with and without left axis deviation (LAD) on ECG, were compared with 17 normal subjects to evaluate the right ventricular contraction sequence and pattern in detail. Blood pool scintigrams were obtained in the left anterior oblique projection, and these images were analyzed by first component Fourier harmonics.In the normal subjects, the phase value distribution representing the pattern of ventricular contraction was almost homogeneous in both the right and left ventricles (RV & LV). In the CRBBB patients without LAD, the phase images showed apparent phase delay in the right ventricle. In the CRBBB patients with LAD, the phase images showed many different contraction patterns varying from normal to RV phase delay, owing to the effects of the hemiblock. Quantitative analysis of the absolute values, showed that the mean (RV-LV) value was 6.6±8.4 msec in the normal subjects. In the CRBBB patients without LAD, the duration of the QRS complex correlated with the mean (RV-LV) value, whereas no difference was observed between the duration of the QRS complex and the standard deviation of the right ventricle. Using phase analysis the degree of the RBBB can be determined from the phase images, and can be quantitatively analyzed as in electrical studies.

Ga-67 scintigraphy in chromomycosis

We examined an interesting case of chromomycosis that had a characteristic Ga-67 accumulation. This patient had had widespread chromomycosis skin lesions for 8 years. We performed Ga-67 scintigraphy in an attempt to obtain additional information on the site and extent of the lesion. Ga-67 scintigraphy revealed not only all subcutaneous nodules but also an unsuspected enlarged lymphnode and a visceral lesion. This case indicates that Ga-67 scintigraphy is a very useful method to use in detecting the site and extension of chromomycosis, especially in the nodal and the visceral lesions, and sometimes might help in differential diagnosis.

Perfusion and mechanical analysis with technetium-99m 2-methoxy-isobutyl-isonitrile in a case of dilated cardiomyopathy

With technetium-99m 2-methoxy-isobutyl-isonitrile (99mTc-MIBI), regional wall thickening in a patient with dilated cardiomyopathy was analyzed by the first component Fourier method. The regional wall thickening was compared with thallium-201 and99mTc-MIBI SPECT imaging. Thallium-201 SPECT images showed mildly reduced perfusion in the posterior wall and redistribution in the septum, whereas99mTc-MIBI images showed heterogeneous accumulation around the left ventricular circumference. By means of phase analysis, diffusely decreased wall thickening and discontinuity of percent wall thickening in neighboring segments were observed throughout the left ventricle. Regional wall motion and wall thickening correlated roughly. However, discrepancies between the mechanical function and myocardial perfusion, and discrepancies in regional myocardial perfusion between thallium-201 and99mTc-MIBI were observed.