Comparison of myocardial fatty acid metabolism with left ventricular function and perfusion in cardiomyopathies: by<Superscript>123</Superscript>I-BMIPP SPECT and<Superscript>99m</Superscript>Tc-tetrofosmin electrocardiographically gated SPECT

Objective: To investigate myocardial fatty acid metabolism and its relationship with left ventricular (LV) function and perfusion in hypertrophic cardiomyopathy (HCM) and dilated cardiomyopathy (DCM).Methods: Thirty-nine patients with cardiomyopathies (58±14 y), comprising 15 DCM and 24 HCM, and 9 age-matched healthy controls were studied with¹²³I-15-(p-iodophenyl)-3-(R,S)-methylpentadecanoic acid (BMIPP) and^99mTc-tetrofosmin (TF) electrocardiographically gated SPECT. As parameters of myocardial fatty acid metabolism, the heart-to-mediastinum ratio (H/M) and global washout of BMIPP were calculated from early and delayed planar images, while regional BMIPP uptake and washout were calculated from SPECT. In TF study, the H/M (H/M-TF) and LV ejection fraction (LVEF) were calculated as global parameters of perfusion and function, while regional TF uptake and wall thickening index were calculated as regional parameters of perfusion and function using the Quantitative Gated SPECT software. The differences in the parameters and the correlations between the parameters from the 2 studies were investigated by one-way ANOVA and multiple linear regression analysis.Results: BMIPP uptake was decreased (p<0.05), and its washout was increased (p<0.05) in DCM and HCM. In multiple linear regression analysis, global BMIPP parameters showed no significant correlation with LVEF (p>0.05), but showed a significant correlation with H/M-TF (p<0.05) in DCM and HCM. According to the partial correlation coefficient, early H/M was the only significant factor (p<0.05) for predicting H/M-TF in DCM and HCM. Multiple linear regression analysis on regional parameters showed regional BMIPP parameters had no correlation with regional function (p>0.05) but had a significant correlation with regional perfusion (p<0.0001) in DCM. In HCM, regional BMIPP parameters showed significant multiple linear correlations with both regional function (p<0.005) and perfusion (p<0.0001). According to the partial correlation coefficients, delayed regional BMIPP uptake was the most significant factor for predicting regional function in HCM, while early regional BMIPP uptake was the only or the most significant factor for predicting regional perfusion in DCM and HCM, respectively.Conclusion: In DCM, BMIPP uptake and washout could not reflect LV function. In HCM, regional delayed BMIPP uptake might be useful for evaluating regional function. In DCM and HCM, early BMIPP uptake might be largely determined by myocardial perfusion.     

Single-photon agents for tumor imaging:<Superscript>201</Superscript>TI,<Superscript>99m</Superscript>Tc-MIBI,and<Superscript>99m</Superscript>Tc-tetrofosmin

This review aims at fostering comprehension and knowledge not only for expert physicians who can skillfully handle various techniques for tumor imaging but also for young practitioners in the field of nuclear medicine. As image processing software and hardware become smaller, faster and better, SPECT will adapt and incorporate these advances. A principal advantage of SPECT over PET is the more widespread availability of the equipment and lower cost for the introduction of the system in community-based facilities. Moreover, SPECT has become less dependent on a limited number of acknowledged experts for its interpretation owing to a variety of handy computer tools for imaging analyses. The increasing use of PET in tumor imaging is not necessarily proportional to the decline of SPECT. General physicians' attention to SPECT technology would also increase more by evoking their interest in "tracer imaging."     

Evaluation of brain tumor recurrence by <Superscript>99m</Superscript>Tc-tetrofosmin SPECT: a prospective pilot study

Objective The differentiation between brain tumor recurrence and post-irradiation injury remains an imaging challenge. Computed tomography (CT) and magnetic resonance imaging (MRI) cannot always distinguish between the two. Although glioma cell line studies substantiated a plausible imaging superiority of ^99mTc-tetrofosmin (^99mTc-TF) over other radiopharmaceuticals, little has been reported on its in vivo imaging properties. We assessed ^99mTc-TF single-photon emission CT (SPECT) in cases where morphologic brain imaging was inconclusive between recurrence and radionecrosis. Methods A total of 11 patients (7 men, 4 women) were evaluated. The initial diagnosis was glioblastoma multiforme (4), anaplastic astrocytoma (1), anaplastic oligodendroglioma (3), grade-II astrocytoma (2), and low-grade oligodendroglioma (1). All patients had been operated on and then received adjuvant external-beam radiotherapy. After a mean follow-up period of 25 months, there was clinical suspicion of recurrence, for which ^99mTc-TF SPECT was performed. Results In 8/11 cases, an abnormally increased tracer uptake appeared in the region that CT and/or MRI indicated as suspicious; in half of these cases, recurrence was confirmed histologically after surgery and in the other four by growth of the lesion over a 6-month follow-up period, and clinical deterioration. The remaining 3/11 patients had faint tracer uptake in the suspicious region, compatible with radiation injury; these lesions remained morphologically unaltered in a mean 12-month follow-up period, with no clinical deterioration in the patient's condition, a course strongly favoring the diagnosis of radiation injury. Conclusions Metabolic brain imaging by ^99mTc-TF could offer useful information in the workup of treated brain tumors, where radiomorphologic findings between recurrence and radionecrosis are inconclusive.     

Reduction of <Superscript>99m</Superscript>Tc-sestamibi and <Superscript>99m</Superscript>Tc-tetrofosmin uptake in MRP-expressing breast cancer cells under hypoxic conditions is independent of MRP function

Hypoxia reduces the uptake of technetium-99m sestamibi (MIBI) in human cancer cell lines. In the current investigation, we attempted to identify the relationship between hypoxia-induced alteration of ^99mTc-MIBI accumulation and expression of multi-drug resistance-associated protein (MRP) in the MCF7/WT breast cancer cell line and its subclonal cell line, MCF7/VP, which expresses high levels of MRP1. A second cationic compound, ^99mTc-tetrofosmin (TF), was also examined. Cellular uptake of ^99mTc-MIBI and ^99mTc-TF was significantly higher in parental MCF7/WT cells than in MCF7/VP cells. Hypoxic conditions generated with a mixture of 95% N₂ and 5% CO₂ reduced cellular uptake of the two tracers in both parental MCF7/WT cells and MRP1-expressing MCF7/VP cells. Cell binding assay with iodine-125-labelled anti-MRP1 antibody demonstrated its specific binding to MCF7/VP cells. Hypoxia did not affect the amount of antibody bound to MCF7/VP cells. These results indicate that hypoxia-induced reduction of tracer uptake in tumour cells is a phenomenon independent of MRP function.     

Evaluation of right and left ventricular function by quantitative blood-pool SPECT (QBS): Comparison with conventional methods and quantitative gated SPECT (QGS)

Though quantitative ECG-gated blood-pool SPECT (QBS) has become a popular tool in research settings, more verification is necessary for its utilization in clinical medicine. To evaluate the reliability of the measurements of left and right ventricular functions with QBS, we performed QBS, as well as first-pass pool (FPP) and ECG-gated blood-pool (GBP) studies on planar images in 41 patients and 8 healthy volunteers. Quantitative ECG-gated myocardial perfusion SPECT (QGS) was also performed in 30 of 49 subjects. First, we assessed the reproducibility of the measurements of left and right ventricular ejection fraction (LVEF, RVEF) and left and right ventricular end-diastolic volume (LVEDV, RVEDV) with QBS. Second, LVEF and RVEF obtained from QBS were compared with those from FPP and GBP, respectively. Third, LVEF and LVEDV obtained from QBS were compared with those from QGS, respectively. The intra- and inter-observer reproducibilities were excellent for LVEF, LVEDV, RVEF and RVEDV measured with QBS (r = 0.88 to 0.96, p < 0.01), while the biases in the measurements of RVEF and RVEDV were relatively large. LVEF obtained from QBS correlated significantly with those from FPP and GBP, while RVEF from QBS did not. LVEF and LVEDV obtained from QBS were significantly correlated with those from QGS, but the regression lines were not close to the lines of identity. In conclusion, the measurements of LVEF and LVEDV with QBS have good reproducibility and are useful clinically, while those of RVEF and RVEDV are less useful compared with LVEF and LVEDV. The algorithm of QBS for the measurements of RVEF and RVEDV remains to be improved.     

Comparison of emory and cedars-sinai methods for assessment of left ventricular function from gated myocardial perfusion SPECT in patients with a small heart

To evaluate the effect of left ventricular (LV) size on the calculation of LV function from gated myocardial SPECT with Emory and Cedars-Sinai programs, we performed 99mTc-tetrofosmin gated SPECT on 49 patients with ischemic heart disease. End-diastolic volume (EDV), end-systolic volume (ESV), and ejection fraction (EF) were semi-automatically calculated by each program. All patients underwent left ventriculography (LVG) within 3 months before and after the SPECT study. We grouped the patients into 22 with a calculated ESV obtained from LVG of over 50 ml (group A) and 27 with an ESV value of 50 ml or below (group B). We then compared the ESV values from gated SPECT with those from LVG in each group. In group A, the ESV from both Emory and Cedars-Sinai programs similarly correlated well with those from LVG (r = 0.92 and r = 0.93, respectively), but in group B, the ESV calculated from the Cedars-Sinai program correlated less with those from LVG (r = 0.53) than those from the Emory program did (r = 0.70). The calculated LV volumes had more errors in the Cedars-Sinai program than in the Emory program, when a patient had a small heart.     

Incremental prognostic value of <Superscript>99m</Superscript>Tc-tetrofosmin myocardial SPECT after percutaneous coronary intervention

Objective  Percutaneous transluminal coronary angioplasty is a well-established therapeutic method in selected patients with coronary artery disease. The aim of this study was to assess the incremental prognostic value of technetium-99m (^99mTc)-tetrofosmin myocardial gated-single- photon emission computed tomography (SPECT) in asymptomatic patients after coronary artery stenting. Methods  A total of 246 consecutive patients (aged 55.5 ± 8.2 years, 182 men) participated in the study with a median follow-up of 9.5 years (interquartile ra 5.8–10.5 years). All patients underwent exercise gated-SPECT myocardial imaging within 5–7 months. Myocardial scintigrams were performed using 99mTctetrofosmin, and were evaluated calculating the summed stress score (SSS), summed rest score (SRS), and summed difference score (SDS) indexes. Cardiovascular death and non-fatal myocardial infarction were considered as hard cardiac events, and late revascularization (>3 months after myocardial SPECT) procedures as soft events. Receiver-operating characteristic (ROC) analysis was used to test the prognostic ability of SSS and SDS for cardiac events. Cox proportional hazards models were used to evaluate the incremental value of SPECT variables. Results  Cardiac death occurred in 12 (4.9%) patients and non-fatal myocardial infarction in 20 (8.1%) patients. In addition, 60 (24.4%) patients underwent a late revascularization procedure. Using ROC analysis the optimal cut-offs of SSS (AUC = 0.94; 95% CI 0.92–0.97) and SDS (AUC = 0. 76; 95% CI 0.70–0.82) for the prediction of cardiac events were 10 and 1.7, respectively. Multiple Cox regression analyses revealed that SSS > 10 (HR = 24.2; 95% CI 7.44–78.79) and SDS > 1.7 (HR = 2.72; 95% CI 1.23–6.00) provided incremental prognostic value over clinical and exercise test data for the composite end points of any cardiac event. Conclusions   ^99mTc-tetrofosmin myocardial gated- SPECT, performed 6 months post-percutaneous coronary intervention (PCI), provides incremental prognostic information for the prediction of cardiac events in asymptomatic patients after PCI.     

Validation of left ventricular volume measurements by gated SPECT 99mTc-labeled sestamibi imaging

Background  Previous studies have shown that gated single photon emission computed tomography (SPECT) technetium 99-labeled sestamibi imaging provides accurate and reproducible measurement of left ventricular (LV) ejection fraction (EF), wall motion, and thickening. This study examined the reliability of gated SPECT sestamibi imaging in measuring LV end-diastolic volume (EDV), end-systolic volume (ESV), and stroke volume (SV). Methods and Results  Gated SPECT measurements were compared with an independent nongeometric method based on thermodilution SV and first-pass radionuclide angiographic EF (using a multicrystal gamma camera). Twenty-four patients aged 58±11 years underwent cardiac catheterization and coronary angiography for evaluation of chest pain syndromes. None had primary valvular disease, intracardiac shunts, or atrial fibrillation. Results  The correlation between the two methods were as follows: EDV: r=0.89, P<.001; ESV: r=.938, P<.001; SV: r=0.557, P<.001. Bland-Altman plots showed mean differences (±standard deviation [SD]) for EDV of −14.3±33.3 mL, for ESV of −0.4±23.7 mL, and for SV of −13.9±15.2 mL. The reproducibility of measuring EDV and ESV by gated SPECT was very high (r=0.99 each). Conclusion  Gated ^99mTc-labeled sestamibi SPECT provides reproducible LV volume measurements. With validation of volume measurement, gated SPECT provides comprehensive assessment of regional and global LV function. This information is important in many patient groups such as those with ischemic cardiomyopathy, concomitant coronary and valve disease, and those who have had myocardial infarction. It will also be useful to assess the incremental value of LV volumes in risk assessment. Presented in part at the 47th Annual Meeting of the American College of Cardiology, Mar. 29–Apr. 1, 1998, Atlanta, Ga. Supported by a research grant from DuPont Pharmaceutical, Billerica, Mass. Various nuclear medicine hardware and software manufacturers have an agreement with Cedars-Sinai Medical Center through which the Medical Center receives royalties based on the distribution of the quantitative gated SPECT software.     

Brown adipose tissue: Evaluation with<Superscript>201</Superscript>Tl and<Superscript>99m</Superscript>Tc-sestamibi dual-tracer SPECT

Brown adipose tissue is one kind of adipose tissue and regulates body temperature and balance of energy via non-shivering thermogenesis. The authors present a case that strongly suggested the presence of activated brown adipose tissue in the neck, shoulders and axillary space by increased 18F-FDG uptake. 99mTc-sestamibi and 201Tl dual-tracer SPECT study showed increased 99mTc-sestamibi uptake and non-increased 201Tl uptake in the corresponding 18F-FDG uptake sites. Brown adipose tissue has dense mitochondria in the cells, which play an important role in thermogenesis. 99mTc-sestamibi uptake and retention depend on the mitochondrial activity but 201Tl uptake does not. Therefore, the activity of mitochondria in activated brown adipose tissue may explain the discrepant uptake between 99mTc-sestamibi and 201Tl.     

<Superscript>99m</Superscript>Tc-ECD brain perfusion SPECT in hyperalgesic fibromyalgia

Purpose Neuro-imaging studies with ^99mTc-HMPAO SPECT in fibromyalgia (FM) patients have reported only limited subcortical hypoperfusion. ^99mTc-ECD SPECT is known to provide better evaluation of areas of high cerebral blood flow and regional metabolic rate. We evaluated a homogeneous group of hyperalgesic patients with FM using ^99mTc-ECD SPECT. The aim of this study was to investigate brain processing associated with spontaneous pain in FM patients. Methods Eighteen hyperalgesic FM women (mean age 49 years, range 25–63 years; American College of Rheumatology criteria) and ten healthy women matched for age were enrolled in the study. A voxel-by-voxel group analysis was performed using SPM2 (p<0.05, corrected for multiple comparisons). Visual Analogue Scale score for pain was 82±4 at the time of the SPECT study. Results Compared with control subjects, we observed individual brain SPECT abnormalities in FM patients, confirmed by SPM2 analysis, with hyperperfusion of the somatosensory cortex and hypoperfusion of the frontal, cingulate, medial temporal and cerebellar cortices. Conclusion In the present study, performed without noxious stimuli in hyperalgesic FM patients, we found significant hyperperfusion in regions of the brain known to be involved in the sensory dimension of pain processing and significant hypoperfusion in areas assumed to be associated with the affective-attentional dimension. As current pharmacological and non-pharmacological therapies act differently on the two components of pain, we hypothesise that SPECT could be a valuable and readily available tool to guide individual therapeutic strategy and provide objective follow-up of pain processing recovery under treatment.     

<Superscript>11</Superscript>C-methionine uptake in cerebrovascular disease: A comparison with<Superscript>18</Superscript>F-FDG PET and<Superscript>99m</Superscript>Tc-HMPAO SPECT

OBJECTIVES: Carbon-11-L-methyl-methionine (11C-methionine) has been reported to be useful for evaluating brain tumors, but several other brain disorders have also shown signs of high methionine uptake. We retrospectively evaluated the significance of 11C-methionine uptake in cerebrovascular diseases, and also compared our results with those for 18F-FDG PET and 99mTc-HMPAO SPECT. METHODS: Seven patients, including 3 patients with a cerebral hematoma and 4 patients with a cerebral infarction, were examined. All 7 patients underwent both 11C-methionine PET and 99mTc-HMPAO SPECT, and 6 of them underwent 18F-FDG PET. RESULTS: A high 11C-methionine uptake was observed in all 3 patients with cerebral hematoma. Increased 99mTc-HMPAO uptake was observed in 2 out of 3 patients, and all 3 patients had decreased 18F-FDG uptake. Of 4 patients with a cerebral infarction, high 11C-methionine uptake was observed in 3. Increased 99mTc-HMPAO uptake was also observed in one patient, whereas 3 patients had decreased 18F-FDG uptake. CONCLUSIONS: We should keep in mind that high 11C-methionine uptake is frequently observed in cerebrovascular diseases. CVD should therefore be included in the differential diagnosis when encounting patients with a high 11C-methionine uptake.     

<Superscript>99m</Superscript>Tc sestamibi myocardial perfusion scintigraphy with the novel use of metamizol for the detection of perfusion reversibility

PURPOSE: This study aims to investigate whether induction with metamizol, an analgesic-antipyretic drug having spasmolitic activity, could be used to increase the detectability of ischemic/jeopardized myocardium during MPS (myocardial perfusion scintigraphy). MATERIALS AND METHODS: Metamizol-enhanced rest MPS (45 min after administration of 1 g metamizol orally, 740 MBq (99m)Tc sestamibi was injected, MPS was acquired 45 min later) was performed in 21 patients who had perfusion defects on their previous stress-rest (99m)Tc sestamibi MPS. Blood pressure was monitored at 15-min intervals. Stress, rest, metamizol-rest MPS images were interpreted on the model of 20 segments using a visual uptake score (VUS; 0 = normal, 1 = mild, 2 = moderate, 3 = significant decreases, 4 = no uptake). (99m)Tc sestamibi uptake ratios (MIBI-UR; mean counts in the region of the perfusion defect/mean counts in the region of the normal-perfused wall) were obtained on each MPS and compared with each other. Average MIBI-UR in each scintigraphic examination was calculated. MPS were compared with coronary angiography results. RESULTS: VUS and MIBI-UR results showed that metamizol-rest MPS displayed the defect reversibility better than rest MPS. Of the 14 segments with fixed perfusion defects on stress-rest MPS, 8 showed improvement of perfusion after metamizol induction. In 33 segments, lesion reversibility was better delineated on metamizol-rest MPS. Metamizol-induced sestamibi uptake was significantly higher (p < 0.001) than stress/baseline rest examinations as calculated by the MIBI-UR. Blood pressure remained unaltered. Coronary angiography results were in concordance with metamizol induced MPS. CONCLUSIONS: Metamizol-enhanced rest MPS increases detectability of ischemic/viable myocardium during MPS. Metamizol should be discontinued like nitrates before stress MPS since it may mask the visualization of ischemic perfusion defects.     

Evaluation of regional myocardial perfusion in patients with severe left ventricular dysfunction: Comparison of 13N-ammonia PET and 99mTc sestamibi SPECT

Objective

Positron emission tomography (PET) scanning with ¹³N-ammonia and ¹⁸FDG is well established for the detection of myocardial viability. Due to the limited availability of PET facilities, recent studies have combined technetium 99m sestamibi single photon emission computed tomography (SPECT) with ¹⁸FDG PET or ¹⁸FDG SPECT. This approach enables simultaneous assessment of regional myocardial blood flow and metabolism and substantially increases the capacity for viability detection. To validate whether ^99mTc-Sestamibi SPECT can replace ¹³N-ammonia PET, we compared these two modalities in patients with severe left ventricular dysfunction due to coronary artery disease.

Materials and Methods

Thirty-one patients (mean age 57±8 years; mean ejection fraction 27%±8%) with angiographically verified coronary artery disease were included. In random order, ammonia-PET and sestamibi-SPECT scans were performed. In a 20-segment model of the left ventricle, two blinded observers scored a total of 610 segments on a five-point scale. In a subset of 20 patients, 400 segments were scored twice to evaluate the observer variations of the two techniques. Segmental score differences were used to compare the imaging modalities. The impact on viability detection was assessed by combining the two flow tracers with FDG PET.

Results

Segmental comparison of the PET and SPECT studies yielded similar (difference ≤1) results in 74% of segments, reflecting regional concordance values in the lateral, apical, anterior, septal, and inferior myocardial walls of 86%, 82%, 71%, 66%, and 63%, respectively. The differences in the septal and inferior walls were primarily due to overestimation of perfusion defects by sestamibi SPECT, which yielded a higher proportion of mismatch patterns in those regions. The overall observer variations of the PET and SPECT studies were 7.5% and 5.8%.

Conclusion

Myocardial perfusion imaging with ¹³N-ammonia PET and ^99mTc-sestamibi SPECT yielded similar results in patients with severe left ventricular dysfunction, except for the septal and inferior regions. In these regions, SPECT tended to overestimate perfusion defects. Hence, attenuation correction should be considered when combining FDG PET and sestamibi SPECT for diagnosing myocardial viability to avoid overestimation of mismatch patterns in those regions.     

Validation of left ventricular volume measurements by gated SPECT Tc-labeled sestamibi imaging

Background. Previous studies have shown that gated single photon emission computed tomography (SPECT) technetium 99-labeled sestamibi imaging provides accurate and reproducible measurement of left ventricular (LV) ejection fraction (EF), wall motion, and thickening. This study examined the reliability of gated SPECT sestamibi imaging in measuring LV end-diastolic volume (EDV), end-systolic volume (ESV), and stroke volume (SV).Methods and Results. Gated SPECT measurements were compared with an independent nongeometrie method based on thermodilution SV and first-pass radionuclide angiographic EF (using a multicrystal gamma camera). Twenty-four patients aged 58 ± 11 years underwent cardiac catheterization and coronary angiography for evaluation of chest pain syndromes. None had primary valvular disease, intracardiac shunts, or atrial fibrillation.Results. The correlation between the two methods were as follows: EDV: R = 0.89, P < .001; ESV: R = .938, P < .001; SV: R = 0.577, P < .001. Bland-Altman plots showed mean differences (± standard deviation [SD]) for EDV of −14.3 ± 33.3 mL, for ESV of −0.4 ± 23.7 mL, and for SV of −13.9 ± 15.2 mL. The reproducibility of measuring EDV and ESV by gated SPECT was very high (r = 0.99 each).Conclusion. Gated ^99mTc-labeled sestamibi SPECT provides reproducible LV volume measurements. With validation of volume measurement, gated SPECT provides comprehensive assessment of regional and global LV function. This information is important in many patient groups such as those with ischemic cardiomyopathy, concomitant coronary and valve disease, and those who have had myocardial infarction. It will also be useful to assess the incremental value of LV volumes in risk assessment.     

Benefits of quantitative gated SPECT in evaluation of perioperative cardiac risk in noncardiac surgery

Objective Gated single-photon emission computed tomography (G-SPECT) was used to evaluate cardiac risk associated with noncardiac surgery and determine the benefits and indications of this technique for this type of surgery. Materials and methods Patients scheduled to undergo noncardiac surgery under the supervision of anesthesiologists and subjected to preoperative cardiac evaluation using G-SPECT during the 26-month period between June 2000 and August 2002 were followed for the presence/absence of cardiac events (i.e., cardiac death, myocardial infarction, unstable angina, congestive heart failure, or fatal arrhythmia) during surgery and the postoperative period until discharged. Relationships between the occurrence of cardiac events and preoperative G-SPECT findings were evaluated. Results A total of 39 patients underwent G-SPECT; 6 of the 39 exhibited abnormal ejection fraction (left ventricular ejection fraction, LVEF ≤ 50%) and end-systolic volume (ESV ≥ 50 ml). Surgery was suspended for three of these six patients and cardiac events developed in the remaining three patients. Both abnormal perfusion images (PI) and abnormal wall thickening (WT) were observed in all six patients. All six patients exhibited abnormal LVEF and/or ESV. Three patients had either abnormal PI or WT, and a cardiac event occurred in one of them. Of the five patients who experienced cardiac events during or after surgery, two exhibited a short run of ventricular tachycardia requiring a continuous administering of antiarrhythmic drugs, whereas the remaining three patients exhibited cardiac failure requiring inotropic support following surgery. Conclusions The results of this study indicate that the occurrence of perioperative cardiac events can be predicted by considering the severity of expected surgical stress and preoperative G-SPECT findings for LVEF, PI, and WT. We conclude that G-SPECT is quite useful for cardiac risk assessment in patients undergoing noncardiac surgery.     

Left ventricular shape index assessed by gated stress myocardial perfusion SPECT: Initial description of a new variable

Background  Ventricular remodeling is predictive of congestive heart failure (CHF). We aimed to automatically quantify a new myocardial shape variable on gated myocardial perfusion single photon emission computed tomography (SPECT) (MPS) and to evaluate the association of this new SPECT parameter with the risk of hospitalization for CHF. Methods and Results  A computer algorithm was used to measure the 3-dimensional (3D) left ventricular (LV) shape index (LVSI), derived as the ratio of maximum 3D short- and long-axis LV dimensions, for end systole and end diastole. LVSI normal limits were obtained from stress technetium 99m sestamibi MPS images of 186 patients (60% of whom were men) (control subjects) with a low likelihood of CAD (<5%). These limits were tested in a consecutive series of 93 inpatients (85% of whom were men) having MPS less than 1 week after hospitalization, of whom 25 were hospitalized for CHF exacerbation. Variables associated with CHF hospitalization were tested by receiver operating characteristic curve and multivariate logistic regression analyses. LVSI repeatability was assessed in 52 patients with ischemic cardiomyopathy who had sequential stress MPS within 60 days after the initial MPS without clinical events in the interval between MPS studies. Control subjects had lower end-systolic and end-diastolic LVSIs compared with patients with CHF and those without CHF (P <.001). Receiver operating characteristic curve areas for the prediction of hospitalization as a result of CHF were similar for LV ejection fraction and end-systolic LVSI. End-systolic and end-diastolic LVSIs were independent predictors of CHF hospitalization by multivariate analysis; however, end-systolic LVSI had the greatest added value among all tested variables. Repeatability was excellent for both end-systolic LVSI (R2 = 0.85, P < .0001) and end-diastolic LVSI (R2 = 0.82, P < .001). Conclusion  LVSI is a promising new 3D variable derived automatically from gated MPS providing highly repeatable ventricular shape assessment. Preliminary findings suggest that LVSI might have clinical implications in patients with CHF. Supported in part by grants from Bristol-Myers Squibb Medical Imaging, Inc, Billerica, Mass, and Astellas Pharma US, Deerfield, Ill.     

<Superscript>99m</Superscript>Tc-GSA liver dynamic SPECT for the preoperative assessment of hepatectomy

OBJECTIVE: The purpose of the present study was to devise a predictive index to predict residual liver function before hepatic resection, using technetium-99m diethylenetriamine-penta-acetic acid-galactosyl human serum albumin (99mTc-GSA) liver dynamic single photon emission computed tomography (SPECT). METHODS: Fifty-seven patients with liver disease underwent liver dynamic SPECT with 99mTc-GSA. Dynamic SPECT was performed to obtain the k-value according to the accumulation curve after injection of 99mTc-GSA. The k-value is a mathematical reflection of the rate of disappearance of the circulating radiotracer as it is accumulated into the hepatocytes. We devised an original predictive residual index (PRI) by combining k-value with liver volume (V) and functional liver volume (FV). Correlation between these parameters and results of liver function tests and the grade of liver disease severity was analyzed. We investigated retrospectively the correlation between PRI and post-operative patient prognosis. RESULTS: The k-value slightly correlated with indocyanine green clearance test at 15 mins, bilirubin level and hepaplastin test. FV and V did not correlate with liver function tests. Post-operative complications were observed in 5 patients. The PRI of these patients was below 0.37. When PRI was above 0.38, no patient had hepatic failure. CONCLUSIONS: When PRI is above 0.38, there is a low probability of hepatic failure after hepatectomy. The PRI is useful in preoperative prediction of post-hepatectomy residual liver function in patients with liver disease.     

Simultaneous assessment of Tc-99m-sestamibi and I-123-BMIPP myocardial distribution in patients with myocardial infarction: Evaluation of left ventricular function with ECG-gated myocardial SPECT

123I-labeled 15-(p-iodophenyl)-3R,S-methyl pentadecanoic acid (BMIPP) is a branched-chain free fatty acid that is used to evaluate various cardiac diseases. The aim of the present study was to investigate the relationship between myocardial perfusion (99mTc-sestamibi) and BMIPP uptake, and to correlate perfusion and metabolic alterations with regional left ventricular dysfunction in patients with myocardial infarction (MI). ECG-gated dual-isotope myocardial SPECT was performed on 130 patients with MI with sestamibi (555 MBq) and BMIPP (148 MBq). The patients were classified into 3 groups according to PTCA therapy and the interval between the onset of infarction and RI injection (OR time). Group A (n = 56) included patients whose OR time was less than one month and who had undergone successful PTCA, Group B (n = 36) had OR times of less than one month and had conservative medical therapy, and Group C (n = 38) had OR times of over one month. The severity scores of the dual-isotope images were calculated from the defect scores in 9 segments. From the ECG-gated SPECT data with sestamibi, the left ventricular ejection fraction (LVEF; %) and regional wall motion were determined automatically using the QGS program LVEF obtained from gated SPECT correlated well with the severity scores for sestamibi and BMIPP (r = -0.68 and -0.76, respectively). The delta severity scores (BMIPP scores - sestamibi scores) of Group A were significantly higher than those of the other two groups (3.6 +/- 3.0 vs. 1.5 +/- 1.7 and 1.0 +/- 1.4, p < 0.001 ). The rate of dysfunctional segments with normal sestamihi distribution was significantly higher in Group A than in Group C (20.7% vs. 6.7%, p < 0.001). ECG-gated dual-isotope SPECT is useful since myocardial perfusion, fatty acid metabolism and left ventricular function can be analyzed during a single examination, so that this procedure has the potential to provide comprehensive information when evaluating patients with ischemic heart disease.     

Regional differences between <Superscript>99m</Superscript>Tc-ECD and <Superscript>99m</Superscript>Tc-HMPAO SPET in perfusion changes with age and gender in healthy adults

A number of studies using single-photon emission tomography (SPET) have shown perfusion changes with age in several cortical and subcortical areas, which might distort the results of perfusion imaging studies of neuropsychiatric disorders. Technetium-99m labelled ethyl cysteinate dimer (ECD) and hexamethylpropylene amine oxime (HMPAO) are both used as markers of cerebral perfusion, but have different pharmacokinetics and retention patterns. The aim of this study was to determine whether age and gender effects on perfusion SPET differ depending on whether ^99mTc-HMPAO or ^99mTc-ECD is used. Forty-five subjects (20 male and 25 female, mean age 52.8±6.6 years) were assigned to ^99mTc-HMPAO SPET (HMPAO group), and 39 subjects (24 male and 15 female, mean age 52.6±6.7 years) to ^99mTc-ECD SPET (ECD group). SPET images were obtained about 10 min after intravenous injection of approximately 800 MBq ^99mTc-HMPAO or ^99mTc-ECD using the same SPET scanner. Three-dimensional volumetric magnetic resonance imaging was performed to as7sess morphological changes in the grey matter. All image processing and statistical analyses were performed using SPM99 software. An area in the right anterior frontal lobe showed an increase in perfusion with age only in the HMPAO group, whereas areas in the bilateral retrosplenial cortex showed decreases in perfusion with age only in the ECD group; neither group showed corresponding changes in the grey matter. The present study shows that different effects of age on perfusion are observed depending on whether ^99mTc-HMPAO and ^99mTc-ECD is used. This suggests that the results of perfusion SPET are differently confounded depending on the tracer used, and that perfusion SPET with these tracers has limitations when used in research on subtle perfusion changes.     

Abnormal retention of<Superscript>99m</Superscript>Tc-TF in a hamster model of cardiomyopathy analyzed by<Superscript>99m</Superscript>Tc-TF and<Superscript>125</Superscript>I-BMIPP autoradiography

OBJECTIVE: Enhanced washout of 99mTc-tetrofosmin (TF) has been reported in patients with hypertrophic cardiomyopathy (HCM). Here, using quantitative dual-autoradiography, the relationship between TF retention abnormality and metabolism depicted by 125I-BMIPP uptake was investigated quantitatively in a hamster model of cardiomyopathy. METHODS AND RESULTS: Early and delayed TF images were obtained at 5 min (7 cardiomyopathic and 5 normal hamsters) and 60 min (8 cardiomyopathic and 5 normal hamsters) after injection, respectively. BMIPP image was obtained 5 min after injection. Five cardiomyopathic and 5 normal hamsters were evaluated histologically. Percent uptake of TF and BMIPP in the heart was measured by an auto-well counter. The left ventricular wall was divided into 12 segments, and the relative regional uptake of TF and BMIPP was measured for each segment. Heterogeneity of radioactive distribution was determined by the standard deviation (SD) of radioactive counts in the left ventricular wall on autoradiogram. The uptake of early TF, delayed TF, and BMIPP in cardiomyopathic hamsters was 8.8%, 20.3%, and 25.3% lower than that in normal hamsters, p < 0.05, p < 0.01, and p < 0.001, respectively. In normal hamsters, distribution of radioactivity in all images was homogeneous, and the SD values were about 13. In cardiomyopathic hamsters, heterogeneous distribution was observed on all images, and the degree of heterogeneity was marked on delayed TF and BMIPP images. The SD was 19.7 +/- 1.2 for early TF image, 25.5 +/- 1.4 for delayed TF image, and 31.7 +/- 2.4 for BMIPP image, respectively. A weak linear correlation was observed between the relative regional uptake of the delayed TF and BMIPP in cardiomyopathic hamsters (r = 0.57). Electron microscopy demonstrated ultra-structural changes in mitochondria of cardiomyopathic hamsters. CONCLUSION: Degree of retention abnormality on delayed TF image corresponded to the metabolic abnormality, probably due to mitochondrial dysfunction, depicted on BMIPP imaging.