[Evaluation of imaging before lung volume reduction surgery for pulmonary emphysema; fused image of multi-detector row computed tomography and scintigram].

Lung volume reduction surgery (LVRS) is performed as surgical therapy for severe pulmonary emphysema. In assessing diagnostic imaging indications, emphysematous change is the strongest in the thoracic computed tomography (CT), while the accumulation decrease is most remarkable in ventilation scintigram and lung perfusion scintigram. Preoperative evaluation of imaging using multidetector-row CT (MDCT) and scintigram were performed, and the multiplanar reconstruction (MPR) image of the MD CT and the single photon emission CT (SPECT) image of the scintigram were fused by the workstation. It was possible to evaluate the excision and the range of LVRS easily by looking at the fused image, and it was useful in deciding on the surgical approach. It is believed that accurate, comprehensible imaging information contributed to an improvement in the surgical outcome of LVRS.

New functional polar maps for estimating regional cardiac function using ECG-gated technetium-99m-tetrofosmin SPECT.

OBJECTIVE: The purpose of this work was to develop functional parameters to analyze regional cardiac function using ECG-gated 99mTc-tetrofosmin SPECT. Our goal was to develop a methodology that used slice thickness correction, the generation of a time-activity curve and a polar map. METHODS: Fourteen normal patients without evidence of coronary artery disease were studied. One hour after intravenous injection of 740-1110 MBq (20-30 mCi) 99mTc-tetrofosmin, ECG-gated SPECT data were acquired by dividing a cardiac cycle into 12 frames. The SPECT data were reconstructed from 11 of 12 frames into 3 views. The reconstruction of these images was repeated after performing slice thickness correction. Excluding the effect of different apex-to-base lengths at any frame during a cardiac cycle, 10 short-axis images with the same slice thickness were obtained. Each short-axis image was divided by 40 radii into 40 segments. The time-activity curve was generated from the total counts included in each segment plus both neighboring segments. Subsequently the curve fitting was performed using the second Fourier function. RESULTS: From fitted curves and their differentials, we calculated end-systolic count, end-diastolic count, percent count increase, uptake, peak contraction rate, peak distention rate and contraction time. CONCLUSION: The functional polar maps visually demonstrated regional myocardial function. This method is expected to be helpful for assessing regional cardiac function using 99mTc-tetrofosmin.

External carotid endarterectomy with patch angioplasty using internal jugular vein--two case reports.

A 59-year-old male and a 74-year-old male presented with occlusion of the right internal carotid artery and stenosis at the origin of the ipsilateral external carotid artery manifesting as cerebral ischemia. External carotid endarterectomy with patch angioplasty using the internal jugular vein was performed. Special care was taken to obliterate the stump of the carotid artery using a Weck clip in one case and plication with non-absorbable sutures in the other. Cerebral blood flow in the affected hemisphere was increased after surgery and the patients remained asymptomatic. External carotid endarterectomy has several special aspects such as patch angioplasty and elimination of the stump which must be understood.

[A modified method of cardiac functional analysis for ECG gated SPECT: study of functional G-maps].

To evaluate the cardiac function accurately using ECG gated SPECT images, we performed a modified method of cardiac functional analysis (Functional G-maps). One hour after the intravenous injection of 1,110 MBq of 99mTc-tetrofosmin, gated SPECT data was acquired dividing a cardiac cycle into 12 frames. Every short-axis images were usually reconstructed using first 11 of 12 frames. The reconstruction of these images was repeated performing slice thickness correction. Because the apex-to-base length is different at any frame during a cardiac cycle, 10 slices of short-axis images were obtained with the same thickness for each frame. Subsequently each short-axis image was divided by 40 radii, and the time activity curve was generated from the total counts included in each segment plus both neighboring segments. Afterwards the curve fitting was performed using the second reverse Fourier function. From fitted curves and their differentials, we estimated a variety of parameters including Max (End-systolic count), Min (End-diastolic count), %CI (Percent count increase), Uptake, PCR (Peak contraction rate), PDR (Peak distention rate) and CT (Contraction time). In 5 normal subjects, %Max was greater in the anterior and septal regions, whereas %Min was greater in the apex and lateral regions. %CI and %PCR were similarly greater in the septal, anterior and inferior regions. On the other hand, %PDR in the lateral or inferior region was lower than the values in the other regions. In conclusion, this modified method is expected to be useful for accurate assessment of regional cardiac function and myocardial perfusion.

[Use of 99mTc-labeled myocardial perfusion agents in the Kanto-Koshinetsu area].

We sent out a questionnaire to investigate how the 99mTc-labeled myocardial perfusion agents are used in the Kanto-Koshinetsu area. Answers were obtained from 83 laboratories. Examinations using 99mTc-labeled agents were performed more frequently than those using 201T1 only in 10 of 83 laboratories. Main reasons for not using 99mTc-labeled agents were as follows: two injections required in the stress study, superiority of thallium-201 in the assessment of myocardial viability, a large amount of clinical data cumulated in thallium-201 imaging, and problems caused by abdominal uptake of 99mTc-labeled agents. Comparing purposes of the examinations using 201T1 and 99mTc-labeled agents, evaluation of myocardial viability was more common in 201Tl imaging, meanwhile, detection of myocardial ischemia was more common in imaging with 99mTc-labeled agents. It was pointed out that dual isotope imaging using 201Tl and 99mTc-labeled agents and simultaneous evaluation of myocardial perfusion and cardiac function are clinically feasible as new diagnostic procedures.

How precisely do SPECT images reflect tracer uptake in myocardial infarction? A comparison of thallium-201 and technetium-99m using a myocardial phantom.

OBJECTIVE: We compared the count ratios of 201TI and 99mTc on SPECT images and the true radioactivity in a myocardial phantom to study how precisely SPECT images reflect tracer uptake in myocardial infarction. METHODS: A defect with 20%, 40% or 60% of normal myocardial radioactivity was placed in the anterior or inferior wall of a myocardial phantom to simulate myocardial infarction. Lung radioactivity was kept at 10% or 30% of normal myocardial radioactivity. The count ratio on short-axis SPECT images was calculated using the circumferential profile curve analysis. RESULTS: The count ratios of 201TI and 99mTc SPECT images with an anterior wall defect was lower than the true radioactivity in the phantom. The count ratio on SPECT images with the inferior wall defect was greater than the true radioactivity for the 20% and 40% defects and lower for the 60% defect. CONCLUSION: SPECT images overestimated decreased perfusion in the anterior wall. SPECT images underestimated decreased perfusion for 20% and 40% perfusion defects in the inferior wall.

Comparison of regional myocardial technetium-99m-MIBI uptake between ECG-gated and ungated SPECT imaging.

UNLABELLED: Technetium-99m-MIBI uptake was compared between ECG-gated and ungated SPECT images in 10 normal subjects and 10 patients with coronary artery disease to investigate the effects of wall motion on regional myocardial uptake. METHODS: Left ventricular ejection fraction (LVEF) and wall motion were evaluated using the first-pass data acquired immediately after injection of 1110 MBq 99mTc-MIBI. A transaxial ungated image was reconstructed with cumulative data during a cardiac cycle. For transaxial gated images, data during a cardiac cycle were divided into eight frames and the first seven frames were used. The lateral/septal ratios for ungated and gated images were obtained using the counts in the ROIs drawn in the lateral and the septal walls. RESULTS: In 10 normal subjects, the lateral/septal ratio for gated increased during end-systole. The mean of the lateral/septal ratio was significantly lower for ungated than for gated (1.025 vs. 1.077, p < 0.05). In patients with septal wall asynergy and a normokinetic lateral wall, the mean of the lateral/septal ratios was significantly lower for ungated than for gated (1.267 vs. 1.325, p < 0.01). CONCLUSION: Ungated SPECT acquisition may underestimate regional myocardial uptake when myocardial wall motion is good, therefore, ECG-gated data should be acquired for accurate assessment of regional myocardial uptake of 99mTc-MIBI.

Mechanical efficiency in hypertrophic cardiomyopathy assessed by positron emission tomography with carbon 11 acetate.

This study was performed to assess the relation between the regional work and oxidative metabolism in hypertrophic cardiomyopathy (HCM). By using carbon 11 acetate as a tracer of myocardial blood flow (%A(0)) and oxygen consumption (k value), 12 patients with HCM with asymmetric septal hypertrophy and 10 normal subjects were studied. Regional work rate (RWR) of the left ventricle was estimated by wall stress and wall thickness. %A(0) in hypertrophied septum was similar to that in nonhypertrophied free wall (92.6% +/- 2.8% vs 93.5% +/- 3.8%; p = not significant). However, oxygen consumption was significantly lower in hypertrophied septum than in nonhypertrophied free wall (0.043 +/- 0.011 vs 0.057 +/- 0.013 min(-1); p < 0.001). The k value in nonhypertrophied free wall was similar to the value observed in normal subjects (0.062 +/- 0.013). Average values for RWR in hypertrophied septum, nonhypertrophied free wall, and normal subjects were 0.26 +/- 0.07,0.62 +/- 0.02,and 1.98 +/- 0.15 J/cm3/ min, respectively. Furthermore, the analysis of covariance, in which the effect of RWR was removed as a covariate, revealed that the overall RWR-corrected k value was much larger in patients with HCM (0.109 vs 0.062, p < 0.0001) than expected from the decreased regional myocardial work, suggesting that there was a diffused inefficiency in oxygen consumption. We concluded, therefore, that the relative value of oxidative metabolism in patients with HCM is significantly higher than that of the normal subjects, suggesting the presence of reduced mechanical efficiency.

[Reproducibility of regional cerebral blood flow measurement at rest with autoradiography method using 123I-IMP and SPECT].

Reproducibility of regional cerebral blood flow (rCBF) values obtained by the autoradiography (ARG) method with one SPECT scan and one point arterial blood sampling at 10 min after 123I-N-isopropyl-p-iodoamphetamine (IMP) infusion was evaluated. The variation in the cross calibration factor between SPECT counts and well-type scintillation counts remained 2.2% for 13 months. The error in rCBF by sampling time difference was less than 3% when sampling time was within 10 min +/- 30 sec after infusion. There was a favorable correlation between the rCBF values in two separate resting scans measured by the ARG method in 10 patients (r = 0.907). And the mean ratio of rCBF values by the second study to those by the first study in the cerebellum and cerebral lobes in 10 patients was 0.989 +/- 0.056 (mean +/- SD). There was no significant difference in rCBF values between two separate studies. Reproducibility of rCBF with the ARG method was proved to be good. The ARG method was thought to be useful for the assessment of treatment effects and clinical courses.