Taniguchi M

123I-labelled BMIPP fatty acid myocardial scintigraphy in patients with hypertropic cardiomyopathy: SPECT comparison with stress 201Tl.

123I-labelled 15-(p-iodophenyl)-3-(R,S)-methylpentadecanoic acid (BMIPP) myocardial single photon emission computed tomography (SPECT) was performed in 17 patients with hypertrophic cardiomyopathy, and was compared with 201Tl exercise stress myocardial perfusion SPECT images. Fourteen patients showed asymmetrical hypertrophy, and three demonstrated apical hypertrophy. SPECT was performed 20 min and 3 h after injection of 111 MBq 123I-BMIPP at rest. Exercise stress 201Tl SPECT was performed at 10 min and 3 h after injection and was compared with BMIPP imaging. In 13 patients BMIPP accumulation in the hypertrophied area in the 20 min image was lower than that of 3 h 201Tl uptake. Interestingly, six patients demonstrated 201Tl redistribution in the region where the uncoupling of BMIPP uptake at 20 min and 201Tl accumulation at 3 h after exercise was observed. These findings suggest that impaired fatty acid metabolism or utilization in hypertrophic myocardium and ischaemia or impaired coronary flow reserve may be one of the causes of the abnormality of fatty acid accumulation.

Comparison of 99Tcm-sestamibi and 201Tl-chloride to estimate right ventricular overload in children.

SummaryTo evaluate right ventricular overload in paediatric patients with congenital cardiac disease (n = 25), the uptakes of 201Tl and 99Tcm-sestamibi (99Tcm-MIBI) were compared. 99Tcm-MIBI showed a clearer myocardial border and better contrast between the myocardium and ventricular cavity. Although hepatic activity may influence right ventricular myocardial activity, it did not have significant effect on the quantitative data of myocardial uptake. The right ventricle-to-background (RV/BG) ratio and left ventricle-to-background (LV/BG) ratio were lower with 99Tcm-MIBI than with 201Tl, and the RV/LV count ratio was also significantly lower in the 99Tcm-MIBI study. The parameters fo the RV/LV count ratios showed good correlations between the 201Tl and 99Tcm-MIBI studies. The RV/LV pressure ratio was estimated using the formula: RV/LV pressure ratio = 0.99 (RV/LV®) + 0.02 (R = 0.90, P < 0.0001). To estimate RV overload or the RV/LV pressure ratio scintigraphically, we conclude that 99Tcm-MIBI be used instead of 201Tl 99Tcm-MIBI studies are a good adjunct to perfusion studies when estimating RV pressure.

Diagnostic values of gallbladder hyperperfusion and the rim sign in radionuclide angiography and hepatobiliary imaging

The diagnostic values of hyperperfusion to the gallbladder fossa and the rim sign were retrospectively evaluated in 24 histopathologically proven cases of gallbladder disease. Although 12 of 13 patients (92%) with acute cholecystitis had nonvisualization of the gallbladder, the positive predictive value with this finding was 71%. However, when the finding was associated with hyperperfusion to the gallbladder fossa or the rim sign, the positive predictive value with both (90%) was markedly increased compared to the prevalence ratio of 54%. Such a combination could be useful for preserving a high positive predictive value in the diagnosis of acute cholecystitis.

Estimation of right ventricular pressure by 201Tl scintigraphy in paediatric cardiac disease.

To estimate right ventricular overload in paediatric cardiac disease, 201 T1 scintigraphy was used to quantify right ventricular uptake. Six methods for calculating the 201 T1 right-to-left ventricular uptake ratio (TRL) were compared, based on the location of regions of interest (ROIs), use of total count or mean count density, and the ROI-based method or profile method. When the TRL was compared with the right-to-left ventricular peak systolic pressure ratio (RVP/LVP), the mean count density method using entire right and left ventricular ROIs seemed to be appropriate, considering its simplicity, reproducibility and regression line. The linear regression line was RVP/LVP=1.15×TRL-0.13 (n=15, P=-0.0001), and RVP(mm Hg)=162× TRL-33 (n = 15, P=0.0001). In four patients with pulmonary stenosis, the changes of TRL were in good agreement with the right ventricular pressure changes after percutaneous balloon valvuloplasty. Thus, evaluation of thallium scintigraphy using this quantitative method can be a simple and effective way to evaluate patients with right ventricular pressure overloading.

Discordant hepatic uptake of Tc-99m HIDA and Tc-99m colloid in a patient with segmental biliary obstruction.

Discordant hepatic uptake between Tc-99m HIDA and Tc-99m colloid occurred in a 63-year-old female with segmental biliary obstruction due to cholangioma. Radiographic CT and a percutaneous transhepatic cholangiogram revealed the obstructed right hepatic duct as well as the dilated intrahepatic duct in the right lobe. At surgery this was confirmed, and a 2 cm mass encasing the right hepatic duct was identified. It should be included in the gamut of discordant hepatic uptake of Tc-99m IDA and Tc-99m colloid.

Functional mapping of ventricular contraction and phase using single-photon emission computed tomography (SPECT).

A method for functional mapping of ventricular contraction and phase was developed using gated blood-pool SPECT. Parameters of contraction and phase were calculated using length-based and count-based Fourier analyses. In length-based Fourier analysis (LFA), percentage-shortening and length-based phase were calculated based on the changes of lengths from a ventricular centre to edges. In count-based Fourier analysis (CFA), phase and amplitude were also calculated using serial tomographic phase images. Two-dimensional polar display format was employed to summarize the SPECT data of whole cardiac surface. This program was applied to evaluate coronary artery disease and conduction anomalies. The polar functional map using gated blood-pool SPECT can be an effective method to integrate three-dimensional cardiac information in conjunction with myocardial SPECT studies.