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J Maddahi

Publications and source records attributed to J Maddahi.

At least 37 records · Page 2Linked to original sources
PubMed1994

Comparative feasibility of separate or simultaneous rest thallium-201/stress technetium-99m-sestamibi dual-isotope myocardial perfusion SPECT.

UNLABELLED: Separate or simultaneous rest 201Tl/stress 99mTc-sestamibi dual-isotope SPECT are potentially efficient myocardial perfusion imaging protocols which combine the use of a high-resolution 99mTc tracer for stress perfusion assessment and 201Tl, the current single-photon agent of choice, for viability assessment. METHODS: To investigate the feasibility of dual-isotope myocardial perfusion SPECT protocols using rest 201Tl and stress sestamibi, 201Tl crosstalk into the 99mTc acquisition window (Group 1, n = 26 patients) and 99mTc crosstalk into 201Tl windows (Group 2, n = 25) were studied. For Group 1, treadmill exercise with sestamibi injection and poststress SPECT ("virgin" sestamibi images) were performed, followed by rest 201Tl injection and SPECT acquisition using dual-isotope windows (contaminated or "dual" images). For Group 2, the order was reversed: rest 201Tl SPECT (virgin 201Tl images) was performed first, followed by exercise sestamibi injection and dual-isotope SPECT. RESULTS: The contribution of 201Tl scatter to the dual sestamibi images (Group 1) was measured to be 2.9% +/- 2.1%, while 99mTc crosstalk contributed 26.7% +/- 13.0% to the dual 201Tl images (Group 2). Image quality was considered good to excellent in 92% of the sestamibi (virgin and dual) images and 88% of the virgin 201Tl SPECT, but only in 23% of the dual 201Tl studies. CONCLUSIONS: Technetium-99m crosstalk into 201Tl windows is substantial; therefore, simultaneous dual-isotope protocols, which involve assessment of 201Tl images contaminated by 99mTc, are not recommended. On the other hand, because of the small amount of 201Tl crosstalk into the 99mTc window, a separate acquisition dual-isotope approach employing the rest 201Tl (virgin)/stress sestamibi sequence is acceptable.

Aged↗
PubMed1994

Multicenter trial validation for quantitative analysis of same-day rest-stress technetium-99m-sestamibi myocardial tomograms.

UNLABELLED: The accuracy of an automated quantitative analysis of same-day rest/stress 99mTc sestamibi SPECT images for detection and localization of coronary artery disease (CAD) was assessed in a multicenter trial consisting of 161 patients from 7 different clinical sites utilizing various camera computer systems. METHODS: Of the 161 patients, 102 had angiographically documented coronary artery disease, 22 had normal coronary arteriograms, and 37 had a low (< 5%) likelihood of coronary artery disease based on their age, sex, symptoms and the results of their exercise electrocardiograms. The patients were studied using previously optimized image acquisition and processing protocols. An additional population consisting of 45 patients with single-vessel disease were evaluated to determine the optimal criteria for detection of CAD. RESULTS: The quantitative analysis method was associated with an overall sensitivity of 87%, specificity of 36%, and normalcy rate (true negative rate in the low likelihood patients) of 81%. Sensitivity for overall detection of disease was similar (90%) in patients with and without myocardial infarction (90% versus 89%). The sensitivities and specificities for identification of disease in individual coronary arteries were, respectively, 69% and 76% for LAD, 70% and 80% for LCX, and 77% and 85% for RCA. CONCLUSION: The results of this study demonstrate that the new objective quantitative method for analysis of same-day rest/stress 99mTc sestamibi SPECT images is accurate for detection and localization of CAD and correlates highly with expert visual interpretation.

Adolescent↗
PubMed1994

Myocardial perfusion imaging with technetium-99m-sestamibi: comparative analysis of available imaging protocols.

Several protocols for rest and stress myocardial perfusion imaging with 99mTc-sestamibi have been developed, each with distinct advantages and disadvantages. The various approaches have similar sensitivities and specificities for detection of coronary artery disease (CAD), but differ mainly in their ability to identify defect reversibility. The dual-isotope approach, with a rest 201Tl study and a stress 99mTc-sestamibi study, permits optimal evaluation of both stress perfusion and defect reversibility. Gated SPECT may be added to any of the protocols and aids in identifying artifacts, defining regional wall thickening and assessing ventricular function. First-pass 99mTc-sestamibi radionuclide angiography can add exercise ventricular function data to the study. Clinical trials have shown that the various protocols for 99mTc-sestamibi provide diagnostic and prognostic information comparable to that derived from traditional 201Tl imaging, with the added advantage of higher quality images and increased certainty in interpretation.

Coronary Circulation↗
PubMed1994

Role of thallium-201 and PET imaging in evaluation of myocardial viability and management of patients with coronary artery disease and left ventricular dysfunction.

The reported mortality of patients with coronary artery disease (CAD) and congestive heart failure is high but variable. In the clinical management of these patients, the available treatment choices are medical therapy, cardiac transplantation and myocardial revascularization. Myocardial revascularization has become an attractive alternative in the management of patients with CAD and poor left ventricular function because medical therapy is associated with a high mortality and cardiac transplantation is expensive and not practical due to shortage of donor hearts. Myocardial revascularization, however, should be recommended in those patients in whom the procedure is very likely to reverse regional and global left ventricular dysfunction and to improve heart failure symptoms and survival. Thallium-201 rest-redistribution myocardial scintigraphy and PET imaging of myocardial perfusion and 18F-fluoro-deoxyglucose metabolism have been extensively evaluated for the assessment of myocardial viability and for prediction of recovery of regional left ventricular dysfunction following myocardial revascularization; with positive and negative predictive accuracies of 72% and 70% for 201Tl rest-redistribution imaging and 83% and 84% for perfusion-metabolism PET imaging. Both modalities also are predictive of improvement in left ventricular ejection fraction after myocardial revascularization. Patients with congestive heart failure who demonstrate the PET pattern of mismatch are more likely to improve their heart failure symptoms following revascularization than those without the mismatch pattern. Furthermore, the PET pattern of mismatch identifies a subgroup of patients who are at very high risk for cardiac death on medical therapy. Survival of these patients can be significantly improved by myocardial revascularization.

Coronary Artery Bypass↗
PubMed1993

Separate acquisition rest thallium-201/stress technetium-99m sestamibi dual-isotope myocardial perfusion single-photon emission computed tomography: a clinical validation study.

OBJECTIVES: This study assessed the validity of a novel approach to myocardial perfusion scintigraphy that provides the opportunity to avoid the drawbacks of standard same-day rest/stress technetium-99m sestamibi myocardial perfusion studies by using separate-acquisition dual-isotope rest thallium-201 and exercise technetium-99m sestamibi single-photon emission computed tomography (SPECT). BACKGROUND: Standard same-day rest/stress technetium-99m sestamibi myocardial perfusion studies are cumbersome, associated with a potential decrease in perceived stress defect severity compared with thallium-201 due to the presence of rest technetium-99m sestamibi and may be unable to differentiate hibernating from infarcted myocardium. METHODS: The dual-isotope procedure was performed in 63 patients without previous myocardial infarction undergoing coronary angiography to evaluate sensitivity and specificity for coronary artery disease and in 107 patients with a low (< 5%) likelihood of coronary artery disease to evaluate normalcy rate. To validate defect reversibility, the dual-isotope SPECT study was compared with stress/rest technetium-99m sestamibi SPECT studies in a separate group of 31 patients with previous documented myocardial infarction who underwent a rest technetium-99m sestamibi study in addition to the dual-isotope SPECT study. RESULTS: In angiographic correlations, dual-isotope SPECT demonstrated high sensitivity for detecting patients with > or = 50% stenosis (91%, 55 patients) and > or = 70% stenosis (96%, 52 patients). In a small group of patients, high specificity was also observed (75% for < 50% stenosis [8 patients] and 82% for < 70% stenosis [11 patients]). A very high normalcy rate of 95% was also found. In the patient group assessed for defect reversibility, in zones with no previous myocardial infarction, segmental agreement for defect type between rest thallium-201 and rest technetium-99m sestamibi studies was 97% (kappa = 0.79, p < 0.001). In myocardial infarct zones, segmental agreement for defect type was 98% (kappa = 0.93, p < 0.001). Image quality was generally good to excellent. CONCLUSIONS: Our findings demonstrate that separate-acquisition dual-isotope myocardial perfusion SPECT is accurate for coronary artery disease detection, correlates well with rest-stress sestamibi studies for assessment of defect reversibility and results in good to excellent image quality. This approach provides an excellent method for the combined assessment of stress myocardial perfusion and myocardial viability.

Aged↗
PubMed1993

Quantitative severity of stress thallium-201 myocardial perfusion single-photon emission computed tomography defects in one-vessel coronary artery disease.

The relation between the quantitative myocardial perfusion defect severity of exercise thallium-201 single-photon emission computed tomography (SPECT) and the quantitative degree of coronary stenosis was examined in 18 patients with 1-vessel disease (> or = 50% diameter stenosis), and abnormal thallium-201 SPECT. A total of 26 vessels were analyzed. Thallium-201 SPECT quantitative defect severity score was derived by summing the number of pixels in a coronary territory in which counts fell below the normal mean and multiplied by the number of SDs by which they fell below the normal mean. The thallium-201 defect severity score was significantly (p < 0.001) related to the maximal percent luminal diameter narrowing (r = 0.93), percent area narrowing (r = 0.89), absolute stenotic area (r = 0.79), and absolute stenotic diameter (r = 0.81). As expected, the strongest relation between thallium-201 defect severity and quantitative angiographic indexes was in the low and high ranges of coronary stenosis, with more variability and lower correlation coefficients (percent diameter: r = 0.75, p < 0.02, percent area stenosis: r = 0.63, p < 0.05) in the middle ranges (50 to 80% diameter stenosis). This observation is likely to be due to the complex flow characteristics across stenotic lesions. The findings suggest that in a select population, thallium-201 defect severity is potentially useful for noninvasive characterization of the functional severity of coronary artery stenosis and may complement coronary angiography in predicting functionally significant stenosis.

Adult↗
PubMed1993

Extracranial head and neck: PET imaging with 2-[F-18]fluoro-2-deoxy-D-glucose and MR imaging correlation.

The aim of this study was to define and quantitate the normal anatomy of the extracranial head and neck with 2-[fluorine-18]fluoro-2-deoxy-D-glucose (FDG) positron emission tomography (PET). This information was used to study 12 patients with primary squamous cell carcinomas. In all cases, the lymphoid tissue of the Waldeyer ring and the palatine and lingual tonsils could be differentiated from the airway, striated muscle, osseous structures, and salivary glands. Striated muscle had markedly less activity than lymphoid or salivary gland tissue. In the 12 patients with primary tumors, FDG PET depicted the tumor as an area of increased activity significantly higher than that of normal tissue. In one instance, FDG PET allowed detection of a tumor not seen at magnetic resonance (MR) imaging or computed tomography. Of the 34 lymph nodes positive for carcinoma, 24 were positive according to MR size criteria and 25 were detected with FDG PET. FDG PET allowed detection of three nonenlarged metastatic nodes that were negative at MR imaging.

Contrast Media↗
PubMed1993

Change induced by radiation therapy in FDG uptake in normal and malignant structures of the head and neck: quantitation with PET.

PURPOSE: To quantitate the changes induced in uptake of the glucose analog 2-[fluorine-18]fluoro-2-deoxy-D-glucose (FDG) in normal structures in the head and neck and compare these to the change in uptake in malignant structures in patients with head and neck tumors undergoing radiation therapy. MATERIALS AND METHODS: Eleven patients with biopsy-confirmed squamous cell carcinoma of the head and neck were studied before, during, and after a 6-week course of radiation therapy with positron emission tomography (PET)-FDG imaging. A ratio of FDG uptake in the structure compared with that in the cerebellum (termed metabolic ratio) within and outside of the field of radiation was determined in the adenoids; lingual and palatine tonsils; parotid, submandibular, and sublingual glands; and nasal turbinates, soft palate, and gingiva. RESULTS: The average metabolic ratio in the tonsils, nasal turbinates, soft palate, and gingiva did not change significantly with treatment. CONCLUSION: FDG uptake in normal structures does not change with radiation therapy. This fact is in marked contrast to the FDG uptake in squamous cell carcinomas in the head and neck, which decrease dramatically with treatment (P < .005).

Adenoids↗
PubMed1993

Automated iterative three-dimensional registration of positron emission tomography images.

Two types of image similarity measures, the sum of absolute differences (SAD) and the stochastic sign change (SSC), were compared for three-dimensional registration of images from PET. To test the accuracy of both registration methods, 30 FDG brain studies, 40 13N-ammonia cardiac studies and 20 FDG liver tumor studies (where each image set contained 15 image planes, 128 x 128 pixels per plane) were made into worse case conditions by creating image sets of low counts and extreme defects. These images were then registered to the reference images that had been moved in three dimensions into a random set of known translations, rotations and normalization factors (x, y, z, theta, rho, sigma, nf). Neither method required any external fiduciary markers or operator interventions to register a set of images. The optimization of the image similarity (using the SAD or SSC) was performed with the simplex method and registration was completed within 10 min of computation time on a low-end workstation. Overall, the SAD method had an average inplane (x, y) registration error of 0.5 +/- 0.5 mm, a z-axis registration error of 1.1 +/- 1.1 mm, an inplane rotational error of 0.5 +/- 0.4 degrees, an out-of-plane rotational error of 1.1 +/- 1.2 degrees and a normalization factor error of 0.015 +/- 0.016. The SSC method had an average inplane (x, y) registration error of 0.6 +/- 0.5 mm, a z-axis registration error of 1.1 +/- 1.1 mm, an inplane rotational error of 0.7 +/- 0.5 degrees, an out-of-plane rotational error of 1.0 +/- 1.2 degrees and a normalization factor error of 0.014 +/- 0.014. This study demonstrates that either the SAD or SSC method for measuring image similarity, combined with the simplex method for function optimization, are accurate methods for registration of a wide variety of PET images including low count studies and those with marked interval changes in the pattern of count distribution.

Brain↗
PubMed1993

Myocardial perfusion imaging using technetium-99m radiopharmaceuticals.

Research and development in nuclear cardiology have made major contributions to the noninvasive approach for detection of coronary artery disease, to the assessment of disease extent and severity, and for prognostication of cardiac events. This article discusses the use of myocardial perfusion imaging and describes techniques for the evaluation of myocardial viability.

Coronary Circulation↗
PubMed1993

Quantitative same-day rest-stress technetium-99m-sestamibi SPECT: definition and validation of stress normal limits and criteria for abnormality.

Gender-matched stress normal limits and criteria for abnormality for rest-stress 99mTc-sestamibi same-day myocardial perfusion imaging were developed and validated in 160 patients who were imaged using previously developed optimized acquisition, processing and quantitative protocols. The gender-matched mean and standard deviation of the normal response were calculated using 35 male and 25 female patients with a < 5% likelihood of coronary artery disease. Receiver-operating curve analysis using expert visual interpretation as the "gold standard" was used to determine the optimal criteria for abnormality detection, in terms of standard deviations from the mean and minimum defect size for each of the four major zones of the polar map, in a pilot population consisting of an additional 35 male and 25 female patients with a variety of perfusion defects. The optimum standard deviations resulted in the following true-positive/true-negative rates when quantitative results were compared to visual analysis for the anterior, septal, lateral, and inferior segments in the combined male and female pilot populations: 84%/86%, 70%/75%, 86%/76% and 69%/76%, respectively. The final criteria were then applied to a prospective population consisting of 33 male and 7 female patients. This analysis resulted in the following true-positive/true-negative rates for overall perfusion abnormalities and abnormalities of the LAD, LCX and RCA vascular territories: 97%/67%, 94%/73%, 73%/90% and 72%/91%, respectively. The optimized 99mTc-sestamibi stress normal limits and criteria for abnormality correlate well with expert visual interpretation of stress myocardial perfusion defects.

Coronary Disease↗
PubMed1992

Reproducibility of stress redistribution thallium-201 SPECT quantitative indexes of hypoperfused myocardium secondary to coronary artery disease.

To determine the reproducibility of quantitative indexes of hypoperfused myocardium by exercise thallium-201 single-photon emission computed tomography, duplicate studies were performed in 16 stable patients within 1 month. Twenty-three other patients, with intervals up to 13 months between studies, were retrospectively identified from medical records. Symptoms, weight, heart rate achieved and peak systolic blood pressure during the 2 studies were similar. Maximal counts circumferential profiles' polar maps were generated and divided into 3 vascular territories. The hypoperfused myocardium was defined as the percent stress profile points below the normal level. The observed values were compared between the 2 studies for each patient. Defect size ranged from 0 to 73%. The concordance correlation coefficient (a measure of the closeness of the data points to the line of identity) and mean absolute deviation were 0.94 and 4.5%, respectively, when all patients were considered together, 0.93 and 3.2%, respectively in the reproducibility group, and 0.94 and 5.1%, respectively, in the retrospective group. Inter- and intraobserver reproducibility were also very high. For individual vessels, the concordance correlation coefficients were all > or = 0.89 and the mean absolute deviations between 3.7 and 9%. Thus, in stable patients with repeat thallium studies within a year, the percent hypoperfused myocardium is highly reproducible.

Adult↗
PubMed1992

The application of positron emission tomographic imaging with fluorodeoxyglucose to the evaluation of breast disease.

Positron emission tomography (PET) is a computer-aided tomographic imaging technique that uses positron-emitting compounds to trace biochemical processes of tissue, and construct images based on them. The authors applied a whole-body PET imaging technique to patients with breast masses or mammographic abnormalities using the isotope 2-[F-18]-fluoro-2-deoxy-D-glucose (FDG), in a clinical trial to evaluate the feasibility of using PET to identify primary breast cancer, axillary lymph node involvement, and systemic metastases, before surgical resection. Fourteen patients have been entered on this study, 10 of whom proved to have breast cancer. Positron emission tomography correctly predicted the nature of 12 of the 14 primary breast lesions, and correctly determined the lymph node status of 11 of the 14 patients. The authors conclude that PET with FDG has potential as a diagnostic modality for detection of primary breast cancer, particularly in the patient with radiodense breasts by conventional mammography, and that it has potential for the preoperative identification of axillary lymph node metastases.

Adolescent↗
PubMed1992

Quantitative stress-redistribution thallium-201 SPECT using prone imaging: methodologic development and validation.

Prone 201Tl myocardial perfusion SPECT has been shown to improve left ventricular inferior wall counts compared to supine imaging, thus minimizing diaphragmatic attenuation. Prone SPECT quantitative normal limits were developed and prospectively applied to 36 patients who had coronary angiography. The prone imaging table used had a cut-out under cardiac area which increased the average myocardial counts by 10.7% compared to prone SPECT through the standard table. Overall specificity and sensitivity were 80% and 93%, respectively. For the right, left circumflex and left anterior descending coronary arteries, the specificities were 94%, 71%, and 94%; and sensitivities were 88%, 89% and 78%, respectively. The normalcy rate in 55 normal patients was 89%. Incidence and the severity of patients motion in 200 prone SPECT studies were compared to 200 supine SPECT studies. Mild and severe motion occurred in 12% and 4% of the supine studies and in only 3.5% and none of the prone studies, respectively. When compared to supine SPECT, prone SPECT had higher (p less than 0.01) regional counts/pixel in the inferior wall and septum, but required an average increase of 2.9 +/- 1.0 cm in camera to chest wall distance and resulted in a reduction of total myocardial counts. Prone SPECT provides an alternative approach for patients who cannot tolerate supine imaging. It should be considered when inferior wall defects on supine imaging pose a diagnostic dilemma and when motion on supine imaging necessitates repeat acquisition.

Aged↗
PubMed1991

Myocardial perfusion imaging with technetium-99m-labeled agents.

Thallium-201 (201Tl) is suboptimal as a single-photon emitting agent for myocardial perfusion imaging, in view of its low-energy photons and long half-life. To circumvent these limitations, two new myocardial perfusion imaging agents labeled with technetium-99m (99mTc) have been developed. They are Tc-sestamibi and Tc-teboroxime. Clinical trials of myocardial perfusion with both tracers have shown results similar to those obtained with 201Tl for detection of coronary artery disease. Results to date indicate that Tc-sestamibi accurately detects and locates myocardial infarction and can accurately assess both left and right ventricular ejection fractions by the first-pass technique. In addition, research has shown that rest-stress studies can be performed on the same day and that Tc-sestamibi can be used to assess the results of thrombolytic therapy. Tc-teboroxime has excellent myocardial tracer uptake characteristics but is cleared very rapidly from the myocardium. These features make Tc-teboroxime well suited to rapid serial studies. These new technetium myocardial perfusion agents have just become available for routine clinical use and are likely to replace 201Tl in many of its clinical applications.

Animals↗
PubMed1991

Comparison of thallium-201 SPECT and planar imaging methods for quantification of experimental myocardial infarct size.

To compare single photon emission computed tomography (SPECT) and planar thallium-201 (TI-201) myocardial perfusion imaging methods for quantification of left ventricular infarct size, 12 dogs with 6 to 8 hours of closed-chest coronary occlusion and 5 normal dogs were studied. After intravenous administration of TI-201, SPECT and three-view planar images were obtained. After the animals were put to death, hearts were sliced and stained with triphenyltetrazolium chloride (TTC) for planimetric determination of left ventricular infarct size. Infarct size on each SPECT slice and planar image was defined as the percentage of circumferential count profiles falling below the limits derived from normal dogs. Infarct size as a percentage of left ventricular mass was determined from SPECT and planar images before and after correcting for differences in myocardial slice mass from apex to base. The correlation coefficients, the concordance correlation coefficients (reflecting closeness to the line of identity), and the mean absolute deviations of the four methods versus TTC staining were 0.83, 0.77, and 5.1% (SPECT, no correction); 0.85, 0.84, and 3.7% (SPECT with correction); 0.81, 0.42, and 12.9% (planar, no correction); and 0.75, 0.49, and 10.4% (planar with correction). The regression lines did not differ from the line of identity for SPECT, whereas they differed significantly for planar imaging. Thus both SPECT and planar imaging are well suited for quantification of left ventricular infarct size. SPECT, however, appears to be superior to planar imaging, since its regression line more closely approximates the line of identity.

Animals↗