Application of a continuous ventricular function monitor with miniature cadmium telluride detector to patients with coronary artery bypass grafting

A continuous ventricular function monitor with a miniature cadmium telluride detector was evaluated and applied to patients with coronary bypass surgery (CABG). Ejection fraction (EF) at rest and change in EF from rest to exercise and postexercise (Y) measured with the device correlated with that of the gamma camera (X) (Y = 0.86x + 6.8(%), r = 0.87, n = 110, p less than 0.001, and Y = 0.96x + 0.4(%), r = 0.90, n = 37, p less than 0.001 respectively). Left ventricular function during and after supine ergometer exercise was monitored in 54 patients before and after CABG. The EF change from baseline to peak exercise improved from -5.9% +/- 8.9% before CABG to 7.2% +/- 7.9% after CABG (p less than 0.001). In all patients but two, a rapid EF increase just after exercise over baseline EF was observed. This EF "overshoot" during recovery increased from 11.5% +/- 6.5% to 16.4% +/- 6.0% (p less than 0.001) after CABG. The time from the cessation of exercise to EF overshoot decreased from 153 +/- 80 sec to 76 +/- 49 sec (p less than 0.001) after CABG. The continuous ventricular function monitor with a miniature cadmium telluride detector is able to measure EF reliably. Following successful aortocoronary bypass, EF response during exercise improved and the EF overshoot in the recovery phase became faster and higher.

A quantitative approach to technetium-99m hexamethylpropylene amine oxime

A non-invasive, simple method for the quantitative evaluation of brain perfusion is presented using intravenous radionuclide angiography with technetium-99m hexamethylpropylene amine oxime (99mTc-HM-PAO). Graphical analysis was employed for the evaluation of the unidirectional influx constant (ku) of the tracer from the blood to the brain. The ku values were standardized to provide objective and comparable values, brain perfusion indices (BPI), among studied subjects by setting the ratio of ROIbrain size to ROIaorta size at 10. The whole-brain BPI values for the normal control subjects showed a significant negative correlation with advancing age (r = -0.632, P = 0.0204, n = 13). The mean of the whole-brain BPI of 7.0 (SD = 1.4) in 20 patients with cerebrovascular disorders was significantly lower than that of 10.6 (SD = 1.5) in 13 normal control subjects. The BPI measurements showed only minimal intra- and interobserver variability. Changes of the ratio of ROIaorta size and ROIbrain size did not significantly influence the BPI values. Hemispherical BPI values in 19 subjects (n = 38) showed highly significant correlations with the hemispherical mean cerebral blood flow values obtained from Xenon-133 single photon emission tomography (SPET) (r = 0.926, P = 0.0001 for the early picture method and r = 0.932, P = 0.0001 for the sequential picture method). This technique is easy to apply as an adjunct to SPET and may be helpful in the quantitative evaluation of brain perfusion in routine clinical studies.

[Characteristics of the myocardial SPECT images of 99mTc-MIBI and 99mTc-teboroxime]

Characteristics of the myocardial distribution of 99mTc-MIBI and 99mTc-Teboroxime was compared with the myocardial distribution of 201Tl. We made summed myocardial images, in which central three short-axis SPECT slices were added. Rectangular region of interest (ROI) was set on each myocardial segment, and mean counts of each myocardial region was obtained using summed short-axis images. The ratio of inferior-to-anterior mean counts (I/A) was 0.69 +/- 0.20 in 99mTc-MIBI and 0.62 +/- 0.16 in 201Tl. The ratio of inferior-to-lateral mean counts was 0.70 +/- 0.18 and 0.65 +/- 0.13, respectively. Both ratios in 99mTc-MIBI were significantly higher than those in 201Tl (p less than 0.05). 201Tl to 99mTc-MIBI ratios of these two values were 1.11 +/- 0.17 (I/A) and 1.08 +/- 0.16 (I/L). The ratios of I/A and I/L of 99mTc-MIBI were about 10 percent higher than those of 201Tl. 99mTc-Teboroxime dynamic short-axis SPECT images of every three-minute were obtained. The ratios of counts in each wall were calculated similarly. After about 8 minutes, gradual increase in hepatic activity can be a cause of quantitative error in the assessment of SPECT images. We obtained the data with a human cardiac phantom. The myocardial phantom filled with 99mTc or 201Tl was placed in the mediastinal portion that is surrounded by the lung (saw dust) and vertebra (plastic bar). The ratio of I/A was 0.79 and I/L was 0.85 in 201Tl. The I/A ratio was 0.93 and I/L was 0.97 in 99mTc. Both ratios in 99mTc were about 15 percent higher than those in 201Tl.(ABSTRACT TRUNCATED AT 250 WORDS)

Paradoxical enhancement of hypoperfusion single photon emission CT images in epileptic focus with bemegride activation. Observation from subtraction of 99mTc hexamethyl-propyleneamine oxime brain single photon emission CT images

Changes of brain images in single photon emission CTs (SPECTs) before and after intravenous injection of bemegride were examined with simultaneous EEG recording in a patient with occipital lobe epilepsy and in a hysteric patient, using a new method, i.e. subtraction of the SPECT images with 99mTc hexamethyl-propyleneamine oxime. The bemegride injection in the epileptic patient paradoxically intensified the hypoperfusion images as epileptic foci in SPECTs, associated with enhanced interictal epileptic discharges, whereas the hysteric showed no such effects. These findings suggest that the hypoperfusion images closely correlate to the severity of epileptic activity, reflecting a functional rather than a morphological deficit.

Widespread reduction of regional cerebral blood flow during hyperventilation-induced EEG slowing ('buildup'). Observation from subtraction of brain imaging with single photon emission computed tomography using technetium-99m hexamethyl-propyleneamine oxime

To study the pathophysiological mechanisms of hyperventilation-induced EEG showing, i.e., the so-called 'buildup' phenomenon, changes in regional cerebral blood flow (rCBF) were investigated before and during the phenomenon in a 16-year-old woman with headache, thought to be of neurotic origin, by subtraction technique of brain images with single photon emission computed tomography using technetium-99m hexamethyl-propyleneamine oxime (99mTc-HMPAO). The tracer uptake during buildup decreased by 31-42% as compared to baseline values at rest before buildup in all of the measured regions, reflecting a widespread reduction in rCBF. Gas analyses of arterial blood collected during buildup showed a decrease in PaCO2, and increases in PaO2 and pH with a slight decrease in blood pressure and an increase in pulse rate. These results directly demonstrate a close correlation between the hyperventilation-induced EEG and rCBF changes, suggesting that the buildup phenomenon results from cerebral ischemic change, presumably due to cerebral vasoconstriction caused by the PaCO2 decrease.

Asymmetric abnormality of renal perfusion with symmetric function in aortic dissection

Two cases of aortic dissection are presented in which discordance between renal perfusion and function has been demonstrated with Tc-99m DTPA. Renal perfusion on the affected side was decreased on blood flow imaging, whereas renal function, including parenchymal accumulation and excretion assessed by subsequent sequential imaging, were similar for both kidneys. These results suggest that blood flow imaging more readily demonstrates a unilateral renal abnormality in patients with aortic dissection.

Acutely administered haloperidol-induced pattern changes of regional cerebral blood flow in schizophrenics. Observation from subtraction of brain imaging with single photon emission computed tomography using technetium-99m hexamethyl-propyleneamine oxime

Changes in regional cerebral blood flow in brain images with single photon emission computed tomography using technetium-99m hexamethyl-propyleneamine oxime before and after intramuscular injection of haloperidol (0.08 mg/kg) were studied in 5 medicated subjects in their twenties, consisting of 5 schizophrenics and 1 patient with histrionic personality disorder, by a subtraction method of brain images. The haloperidol injection induced two types of perfusion pattern change; in 2 of the schizophrenics, a relative hypoperfusion in the frontal lobes in the images prior to injection was converted to a relative hyperperfusion. In the other 3 schizophrenics and in the patient with histrionic personality disorder, the slight left hemispheric dominance was changed to a marked right hemispheric dominance. The results indicate that haloperidol affects perfusion patterns in schizophrenics.

[Distribution of myocardial damage in patients with hypertrophic cardiomyopathy: evaluation by exercise thallium-201 scintigraphy]

The characteristic of myocardial damage in hypertrophic cardiomyopathy (HCM) was evaluated as to whether the damage is limited to the hypertrophied wall or extends throughout the entire wall. The myocardial damage was detected by exercise thallium-201 (Tl-201) scintigraphy and was evaluated using circumferential profile analysis, calculation of initial uptake and washout rate. Eleven patients with asymmetrical hypertrophy (ASH), whose septal and posterior wall thickness ratio exceeded 1.3 on left ventriculography and biventriculography, and 13 age-matched control subjects without heart disease were studied. The mean values of initial uptake in both groups did not differ significantly, but the washout rate for the entire heart was significantly decreased only in the HCM group (p < 0.05). All of the regional washout rates (antero-septal, apical and postero-lateral) were significantly decreased in the HCM group (p < 0.05), without any difference between the hypertrophied wall and the non-thickened free wall being noted. These results demonstrated that the analysis of myocardial damage by exercise Tl-201 scintigraphy using calculation of the washout rate is a very sensitive means of detecting myocardial damage in HCM, and that such myocardial damage is not restricted to the hypertrophied wall, but rather extends to the entire wall, including the free wall which is not thickened.

Regional cerebral blood flow in patients with schizophrenia. A preliminary report

Regional cerebral blood flow was evaluated using Tc99m-HMPAO SPECT in 10 medicated patients with schizophrenia and 9 healthy volunteers. There were no prefrontal regions in the patient group with lower regional indices than in the control group. However, in the left hippocampal region, relative blood flow was significantly increased in the patient group compared with the control group. Furthermore, there was a relative increase in blood flow in the left basal ganglia of the patient group. A negative correlation coefficient was calculated between the relative blood flow in the left middle prefrontal cortex and the severity of the blunted affect, as well as between the relative blood flow in the left basal ganglia and the severity of the anhedonia-asociality. These findings indicate that prefrontal hypoactivity is not invariably present in all schizophrenics and that left basal ganglial hyperactivity may be associated with the effects of antipsychotic treatment and clinical improvement. Moreover, the left hippocampal hyperactivity may correspond to left limbic dysfunction in schizophrenia.

Thallium-201 SPECT depicts radiologically occult lung cancer

A case of radiologically occult lung cancer is presented in which 201TI SPECT of the chest clearly delineated the involved area. A 66-yr-old man underwent chest screening examinations for asymptomatic smokers and presented a positive sputum cytology for lung cancer. Conventional chest x-ray, tomography of computed radiography, and a CT scan failed to locate the lesion in the lung. Thallium-201 SPECT, however, was successful in depicting the area of the involvement.

Assessment of right ventricular overload by a thallium-201 SPECT study in children with congenital heart disease

Thallium-201 planar and SPECT studies were performed in 38 children with congenital heart disease using high-resolution three-headed SPECT. The 201Tl total or average right ventricular-to-left ventricular (RV/LV) count ratios were measured by summed short-axis images. In the planar study, the RV/LV systolic pressure ratio correlated with 201Tl RV/LV average count ratio (r = 0.91) better than that in the SPECT study (r = 0.78). However, in the SPECT study, patients with atrial septal defect (n = 9), ventricular septal defect (n = 13), tetralogy of Fallot and double outlet right ventricle (n = 6) showed a characteristic distribution in the plot of RV/LV pressure ratio versus 201Tl RV/LV total count ratio. A prospective study showed that the RV/LV average count ratio was a good predictor of RV/LV pressure ratio (n = 19, r = 0.91). Three-headed SPECT is useful for pediatric cardiac studies, and the overload types found in congenital heart disease seemed to be differentiated by the SPECT study.

Synthesis and characterization of 99Tcm-p-halophenethyl diaminodithiol analogs

In an effort to develop new, clinically useful 99Tcm-diaminodithiol (99Tcm-DADT) complexes for the evaluation of regional cerebral perfusion, basic diaminodithiols (DADT-TM, DADT-HM and DADT-MHM) and three diaminodithiol ligands functionalized with p-iodophenethyl (DADT-IPE), N-ethyl-p-fluorophenethyl amine (DADT-EFPE) or N-ethyl-p-iodophenethyl amine (DADT-EIPE), whose chemical structures are analogous to N-isopropyl-p-iodoamphetamine (IMP), were synthesized, labelled with 99Tcm and evaluated comparatively in experimental animals. In addition, the relationships between the chemical properties of the derivatives and their brain uptake and retention were investigated. The results were: (1) Isomeric configuration of 99Tcm-DADT complexes has an influence on uptake and retention in the rat brain. (2) In basic 99Tcm-DADT complexes, a correlation exists between initial brain uptake and lipophilicity, but in 99Tcm-DADT complexes containing a chemical structure similar to that of IMP, no correlation exists. (3) 99Tcm-DADT-IPE has relatively high uptake and long retention in the rat brain.

[Assessment of myocardial viability by 24-hour imaging after stress thallium-201 scintigraphy]

Twenty-four-hour delayed imaging after stress thallium-201 scintigraphy was assessed for more accurate detection of viable myocardium. Thirty-two patients with coronary artery disease who showed fixed perfusion abnormality (FPA) at 3 hr imaging after stress Tl study were evaluated with 24 hr delayed imaging. Of 37 areas with FPA, 19 areas (51%) showed redistribution (RD) at 24 hr imaging. After successful coronary artery bypass grafting (n = 19) or transluminal coronary angioplasty (n = 3), stress Tl scintigraphy was performed. Of 13 areas with RD at 24 hr imaging, 12 revealed improvement of Tl uptake after revascularization. On the other hand, of 12 areas with FPA until 24 hr, 8 showed no improvement. In conclusion, conventional stress Tl-201 scintigraphy underestimates myocardial viability, and additional 24 hr imaging permits more accurate assessment of myocardial viability.

[Cardiac response to exercise before and after coronary artery bypass grafting: evaluation by continuous ventricular function monitor]

Cardiac response to exercise was evaluated with continuous ventricular function monitor (VEST) with cadmium telluride detector. Thirty-nine patients (30 male and 9 female, aged 57 +/- 8, 23 had old myocardial infarction) were monitored with VEST during and after supine ergometer exercise before and 4 weeks after coronary artery bypass grafting (CABG). Left ventricular ejection fraction (EF) responses were classified into 4 types; type A showed EF increase greater than 5% till end of exercise, type B demonstrated initial increase followed by decrease in EF, type C revealed no significant EF change, type D showed continuous EF decrease. Before CABG, each EF response type A, B, C, and D consisted of 4, 2, 12, 21 patients respectively and after CABG each type included 18, 10, 9, 2. The EF change from rest to peak exercise (delta EF-Ex) improved from -6.4 +/- 8.8% to 5.0 +/- 7.4% (p less than 0.001) after CABG. All patients showed rapid EF increase after exercise or "EF overshoot" (EF-OS). After CABG, the EF change from rest to EF-OS (delta EF-OS) and time to EF-OS (T-OS) were improved from 9.9 +/- 5.2% to 14.9 +/- 5.3% (p less than 0.001) and 162 +/- 86 sec to 80 +/- 48 sec (p less than 0.001) respectively. Type A, B patients showed higher delta EF-OS and shorter T-OS than type C, D patients, suggesting EF overshoot was contingent upon cardiac function during exercise. After CABG, in patients with myocardial infarction, T-OS shortened but delta EF-OS showed less improvement than patients without infarction, suggesting loss of myocardium hampered EF-OS.

[Clinical application of Tc-99m HMPAO labeled leukocyte imaging in inflammatory disease]

A radionuclide imaging with Tc-99m HMPAO labeled leukocyte was performed in order to determine its clinical usefulness in inflammatory disease. The mixed leukocyte isolated from 40 ml of whole blood containing 5 ml of acid citrate dextrose A and 7 ml of 6% hydroxyethyl starch was incubated with 370 MBq (10 mCi) of Tc-99m HMPAO at 37 degrees C for 30 minutes. Because the labeling efficiency of Tc-99m HMPAO labeled leukocyte was 60.2 +/- 6.3%, the procedure of washing Tc-99m, leukocyte with 5 ml of physiological saline was necessary before intravenous injection, in order to remove the unlabeled Tc-99m HMPAO. The recoveries of Tc-99m leukocyte in the blood after intravenous injection were 41.1 +/- 6.7% at 5 minutes, 33.4 +/- 2.1% at 30 minutes, and 27.2 +/- 3.4% at 2 hours after injection. Moreover, the labeled leukocyte was not stained with trypan blue. Therefore, the biological activity of the Tc-99m leukocyte was maintained as that of In-111 oxine labeled leukocyte. In the 39 patients with clinical suspicion of inflammatory disease including 15 patients with acute and chronic infectious disease where both Tc-99m leukocyte and Ga-67 citrate imagings were performed, the sensitivity, specificity and accuracy for infectious disease were 47%, 100% and 79% with Tc-99m leukocyte, and 67%, 79% and 74% with Ga-67 citrate. These results suggest that Tc-99m HMPAO labeled leukocyte imaging is promising for evaluating inflammatory disease because of the much higher specificity, the ready availability of Tc-99m HMPAO, the good image quality, and the lower radiation dose to the patient.

201Tl SPECT in the detection of mediastinal lymph node metastases from lung cancer

201Tl SPECT was performed to detect mediastinal involvement in 80 patients with lung cancer who underwent surgery within a week after the SPECT study. Out of 29 patients with mediastinal involvement 16 (55%) were positive on the 201Tl early scan at 15 min postinjection and 22 (76%) were positive on the delayed scan at 3 h. These metastatic lymph nodes tended to be visualized much better on the delayed scan. In all patients with true positive results on the delayed scan, the mediastinal lymph nodes were plural, with a lesion of more than 14 mm in size. Seven false negative cases were found to have metastatic lesions less than 12 mm in size. Both the early and delayed scans showed false positive accumulation in six of 51 patients without mediastinal involvement (specificity 88%). Thus the overall accuracy for the delayed scan was 84%. The 201Tl delayed SPECT is thought to be a good noninvasive method for assessing mediastinal lymph node metastases from lung cancer.

Tc-99m HMPAO SPECT analysis of neuroleptic effects on regional brain function

This report describes a new approach to the evaluation of neuroleptic effects on regional brain function. Using Tc-99m HMPAO SPECT imaging, consecutive brain perfusion studies before and after acute haloperidol administration were performed on three schizophrenic patients and two normal volunteers. The antipsychotic drug ameliorated the hypoactivity in the frontal lobe and suppressed the hyperactivity in the temporo-occipito-parietal lobe selectively in the dominant hemisphere in the schizophrenic patients. It did not exert a significant influence on the brain perfusion pattern in normal volunteers. This nuclear medicine technique seems to be useful for the evaluation of drug effects in psychiatric diseases.

SPECT evaluation of brain perfusion reserve by the acetazolamide test using Tc-99m HMPAO

This report describes a new approach to the evaluation of brain perfusion reserve using Tc-99m HMPAO SPECT. Consecutive brain Tc-99m HMPAO SPECT studies before and after acetazolamide (Diamox) administration were performed within 30 minutes on 19 patients with significant vascular occlusive lesions. Thirteen patients showed decreased perfusion reserve and four patients maintained perfusion reserve in the affected vascular territories after Diamox administration, providing additional information to baseline Tc-99m HMPAO SPECT in 17 (89%) patients. Although flow augmentation post-Diamox was underestimated, possibly due to the nonproportionality of Tc-99m HMPAO activity to true blood flow, significant changes in the brain perfusion pattern were both visually and quantitatively determined using an image subtraction technique. This consecutive Tc-99m HMPAO SPECT technique seems to be of practical use for the evaluation of brain perfusion reserve and for the improvement of the sensitivity of detecting pathologic areas.

[Evaluation of brain perfusion SPECT imaging using 99mTc-ECD]

Fundamental and clinical evaluation was performed on 99mTc-ECD, a new agent for brain perfusion SPECT. Radiochemical purity reaches a plateau of approximately 98% at 30 min after reconstitution and remains stable up to 24 hours later. A biodistribution study showed approximately 5% injected dose in the brain, very slow brain washout of 5.6% per hour on the average, and rapid washout from the other organ mainly through the urinary system. Brain ECD distribution was determined within 2 min postinjection and remained stable for up to 1 hour. Three hours later, slight but significant changes in brain distribution were observed, that were relative reduction of cerebral cortical activity and gray to white matter activity ratio, and relative elevation of white matter and thalamic activities. Comparative studies of ECD images with IMP and HMPAO images revealed that radioactivity contrast between affected and unaffected areas was less prominent in ECD than in IMP in cerebral and cerebellar cortical lesions, more prominent in ECD than in IMP in striatal and thalamic lesions, and somewhat more prominent in ECD than in HMPAO in both lesions. Imaging around 1 hour postinjection seems to be more appropriate than immediate postinjection imaging because of the clearance of the extracranial radioactivity and somewhat better radioactivity contrast between affected and unaffected areas.

Dynamic acquisition with a three-headed SPECT system: application to technetium 99m-SQ30217 myocardial imaging

A method for SPECT data acquisition, "continuous repetitive rotation acquisition," was developed with a high-sensitivity three-headed SPECT system. The method was applied to the dynamic imaging of 99mTc-SQ30217, a new myocardial imaging agent. After acquisition and reconstruction of SPECT data every minute, projection images at arbitrary intervals were used for tomographic reconstruction to determine the best timing of SPECT imaging in 99mTc-SQ30217. Based on a comparison of several possible acquisition intervals, SPECT data acquisition within 9 min after injection is recommended because of high myocardial uptake (myocardium-to-lung ratio, 2.83 +/- 0.42 (mean +/- s.e.m.) at 3-6 min) and relatively low hepatic uptake (myocardium-to-liver ratio, 0.85 +/- 0.13 at 3-6 min). The rate constant of the clearance of 99mTc-SQ30217 from the myocardium obtained by SPECT was: k1 = 0.249 +/- 0.050 per min (average half-life = 2.8 min) and k2 = 0.012 +/- 0.004/min (average half-life = 58 min). The continuous repetitive rotation acquisition SPECT study appears useful for imaging SQ30217 with its rapidly changing myocardial distribution.

[Clinical evaluation of 123I-MIBG for assessment of the sympathetic nervous system in the heart (multi-center clinical trial)]

Multi-center clinical trial of 123I-metaiodobenzylguanidine (123I-MIBG) was carried out to assess its utility as a scintigraphic imaging agent reflecting sympathetic neuronal function in cardiovascular field. Studies were performed on patients with heart diseases of three categories, myocardial infarction, angina pectoris and cardiomyopathy. Scintigraphic images, reflecting sympathetic neuronal function were obtained with 123I-MIBG from all of those categories of patients and the efficacy of the imaging was revealed in 781 (95.0%) out of 822 patients. In some patients abnormality was suggested in sympathetic neuronal function with 123I-MIBG imaging, in spite of normal findings with myocardial perfusion scintigraphy by 201TlCl. In all 981 patients studied with 123I-MIBG, there have been no severe adverse reactions, except complaints of burning on injection site of the agent or nausea, etc. from 4 patients. We conclude that 123I-MIBG imaging is one of the effective tools for diagnostic use reflecting topical sympathetic neuronal function in the heart, judging from its safety and efficacy.

Papillary carcinoma in ectopic thyroid detected by TJ-201 scintigraphy

A 37-year-old man with papillary carcinoma in an ectopic thyroid is presented. Excisional biopsy revealed the cervical mass to be a metastasis from thyroid cancer. X-ray, ultrasonography, and computed tomography, however, failed to identify the primary tumor in the thyroid. Incidental TI-201 uptake was noted in the midline of the anterior neck, and a palpable nodule was discovered in this area. Fine needle aspiration cytology demonstrated Class V papillary adenocarcinoma, and subsequent surgery confirmed a papillary carcinoma in the ectopic thyroid. This case suggests the usefulness of TI-201 scintigraphy for the detection of ectopic thyroid malignancy.

[Basic evaluation of an ambulatory ventricular function monitor with a a cadmium telluride detector]

The reliability of a new ambulatory ventricular function monitor (VEST) with cadmium telluride (Cd-Te) detector was validated. No counting loss was observed under 20 kcps. In phantom study, more than 200 ml with 6 cm distance from the detector and more than 300 ml with 6-12 cm distance, underestimation of volume was observed. Ejection fraction (EF) calculated in phantom study showed close value to the true EF in 50-400 ml of end-diastolic volume. In 10 patients, 1-2 cm detector shift toward right upper, upper and left showed underestimation of EF. Good correlation of gamma camera EF (X) and VEST EF (Y) was obtained (Y = 0.96X + 3.6(%), n = 37, r = 0.93, p less than 0.001). EF change from rest values, obtained from each comparable exercise and post exercise stage by gamma camera (X) and VEST (Y), showed good correlation (Y = 0.95X + 0.8, n = 20, r = 0.85, p less than 0.001). In conclusion Cd-Te VEST was considered as a reliable EF measurement technique similar to gamma camera.