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Biomedical subjects

M E Phelps

Publications and source records attributed to M E Phelps.

At least 127 records · Page 7Linked to original sources
PubMed1994

Intraoperative beta probe: a device for detecting tissue labeled with positron or electron emitting isotopes during surgery.

An intraoperative beta probe was designed, built, and tested for detection of radio-labeled malignant tissues that has the advantage of being selectively sensitive to beta while insensitive to gamma radiation. Since beta radiation (electrons or positrons) has a short range in tissue, this probe is ideal for detecting tracers in tumors at the surface of the surgical field. This probe contains a plastic scintillation detector sensitive to beta rays and to a lesser degree some background gamma rays. A second detector counts spurious gamma rays and allows for their subtraction from the activity measured by the first detector. Sensitivity of the dual probe for I-131 and F-18 was measured to be 108 counts/s/kBq (4000 counts/s/microCi). The dual-detector probe faithfully measured the 10:1 "tumor" to background ratio of radioactivity concentrations in a simulated environment of a tumor in the presence of intense background 511 keV photons. In another phantom experiment, simulating abdominal tumor deposits with various realistic I-131 radioactive concentrations, the probe was able to accurately identify tumors of approximately 50 mg with a tumor/normal radioactivity concentration of 3/1 in 10 s.

Abdominal Neoplasms↗
PubMed1994

Basic principles of positron emission tomography in oncology: quantitation and whole body techniques.

Positron emission tomography (PET) of the brain and heart has made important contributions in clinical and research applications in the fields of neurology and cardiology. The more recent applications of PET in tumor imaging has marked oncology as the next frontier in PET; however, the dilemma of rising health care cost will challenge the application of new technologies. This challenge can be approached by innovative and appropriate use of sophisticated technology in both the research and clinical realms. The current developments of PET imaging technology to accurately stage the extent of tumor, as well as monitor the effectiveness or ineffectiveness of new or current therapies will be an extremely valuable tool in research and in the cost effective management of cancer patients. In the future, the oncologist may be able to adjust the chemotherapy to the tumor response based on PET imaging. In other situations, PET may be able to predict that no existing therapy will elicit a durable response, resolving the patients' and families' uncertainty of whether extreme therapeutic measures would have made a significant difference. This paper reviews some of the recent developments and areas of research in tumor PET imaging, and describes some of the practical and technical aspects involved with FDG tumor quantitation and whole body PET imaging.

Blood Glucose↗
PubMed1994

Quantification of the extent and severity of perfusion defects in canine myocardium by PET polar mapping.

UNLABELLED: This study validates perfusion defect extent and severity as derived by PET polar maps in vivo against measurements derived from radiolabeled microspheres. METHODS: In seven open-chest dogs, either the left anterior descending (n = 11) or left circumflex coronary artery (n = 13) were ligated sequentially from distal to proximal. After each occlusion, gated PET images were acquired with 13N-ammonia (20 mCi) while radiolabeled microspheres were administered into the left atrium. The transaxial PET images were reoriented into left ventricular short-axis cuts, including the apex, and polar maps were generated from circumferential activity profiles. PET polar maps were then compared with polar maps derived from microspheres after normal databases for 13N-ammonia and for microspheres were established. Nitrogen-13 or microsphere activities of less than 1.5 s.d. below the mean were defined as hypoperfused. RESULTS: The extent (percent of left ventricular mass) and mean severity of the hypoperfused myocardium in the postmortem microsphere measurements ranged from 3% to 69% and 3% to 58%, respectively. The estimated extent by summed PET and by microspheres correlated by y = 4.95 + 0.95x (r = 0.91, s.e.e. = 0.085, p < 0.001) and mean severity by y = 5.52 + 0.87x (r = 0.85, s.e.e. = 0.101, p < 0.001). The extent and severity were similar for summed and gated PET studies. CONCLUSION: The current study validated a polar map approach that provides accurate, quantitative assessment of the extent and severity of myocardial perfusion defects in vivo. Gating did not yield an improved correlation between PET and microsphere measurements. Thus, ungated PET images can be used to assess accurately the extent and severity of perfusion defects.

Ammonia↗
PubMed1994

Persistent twenty-four hour SPECT thallium-201 defects, plasma thallium-201 concentrations and PET metabolic viability.

Previous studies have shown that defects on four hour thallium-201 redistribution images often exhibit late reversibility, suggesting that the thallium-201 scintigraphic assessment of myocardial viability might be influenced by delayed redistribution imaging. To assess tissue metabolic activity in segments with late thallium-201 defects, positron emission tomography (PET) with 13NH3 and 18FDG was performed in 26 coronary artery disease patients with left ventricular dysfunction undergoing twenty-four hour SPECT thallium-201 scintigraphy. In 13 patients, plasma thallium-201 levels were obtained at the time of SPECT study and integrated tracer concentrations were determined one, two, four and twenty-four hours following injection. On circumferential profile image analysis of the PET images, ischemia was defined by preserved glucose metabolism in hypoperfused myocardium while infarction was identified by concordant reductions in both perfusion and glucose metabolism. Nineteen patients had stress-redistribution SPECT studies and seven had rest-redistribution SPECT studies. Using a semi-quantitative scoring system, four experienced observers visually identified 100 fixed, 17 partially reversible and twelve completely reversible segmental SPECT thallium-201 defects. On PET, metabolic activity was identified in 51 (51%) fixed defects (21 PET ischemia, 30 PET normal) and nine (53%) partially reversible defects (five PET ischemia, four PET normal). Of the twelve completely reversible thallium-201 defects, six (50%) were normal on PET, five (42%) had PET ischemia and one (8%) had PET infarction. The relative number of fixed thallium-201 defects with metabolic activity on PET did not depend on whether a stress or rest thallium-201 study was performed, or on whether the plasma thallium-201 integral concentration was high or low relative to mean values at any time point. Despite delayed redistribution imaging, PET imaging identifies glucose metabolic activity, and therefore residual tissue viability, in the majority of fixed twenty-four hour thallium-201 defects.

Aged↗
PubMed1994

Evaluation of the effect of glucose ingestion and kinetic model configurations of FDG in the normal liver.

UNLABELLED: The liver plays an important role in glucose homeostasis. PET studies with 2-[F-18]fluoro-2-deoxy-D-glucose (FDG) of the liver (e.g., in neoplasms) require an understanding of the effects of dietary conditions on hepatic FDG uptake. METHODS: Twenty studies were performed on 10 normal volunteers (ages 24 +/- 4) after fasting 4 to 19 hr and again after oral consumption of 100 g of dextrose to investigate tracer kinetic model configurations of FDG in the normal liver and to evaluate the impact of oral glucose on liver in normal subjects. Dynamic PET images were acquired for about 1 hr using a Siemens/CTI 931 tomograph. RESULTS: A three-compartment model with an input function delay time parameter was the statistically preferred model configuration. The model estimated transport rate constant from plasma to liver, K1, increased significantly (p < 0.05) from 0.864 +/- 0.136 ml/min/g in fasting studies to 1.058 +/- 0.269 ml/min/g in postglucose studies. Glucose loading also significantly increased (p < 0.01) the rate constant for FDG phosphorylation, k3, from 0.005 +/- 0.003 min-1 in fasting studies to 0.013 +/- 0.007 min-1 in postglucose administration and, consequently, significantly increased both the phosphorylation fraction (k3/(k2 + k3)) and the influx constant (K1k3/(k2 + k3)). No significant differences in the liver-to-plasma transport rate constant, k2, dephosphorylation constant, k4, or distribution volume of FDG (K1/(k2 + k3)) were observed. CONCLUSION: Dynamic FDG-PET studies can be used to evaluate kinetics of liver glucose metabolism. The results indicate that dietary conditions have a significant effect on hepatic FDG kinetics. Because of the higher net FDG uptake by normal liver after glucose loading, fasting conditions are preferred for FDG liver tumor studies to increase the tumor-to-background contrast.

Administration, Oral↗
PubMed1993

Imaging of pulmonary mass lesions with whole-body positron emission tomography and fluorodeoxyglucose.

BACKGROUND: The clinical staging and management of both primary and metastatic lung lesions depends on accurate imaging techniques. Biochemical imaging with positron emission tomography, (PET), and the glucose analog 2-[18F]-fluoro-2-deoxy-D-glucose, (FDG), complements anatomic imaging with conventional radiologic methods. METHODS: A new "whole-body" PET FDG technique that produces two-dimensional, nontomographic and tomographic longitudinal images of the entire body has been developed at UCLA. Sixteen patients with known pulmonary nodules who had undergone thoracic computed tomography (CT) were studied with whole-body PET FDG imaging at the UCLA Medical Center. RESULTS: This PET FDG imaging method identified metabolically active tumor foci in all eight patients with bronchogenic carcinomas, four patients with metastatic lesions to the thorax, and two patients with Hodgkin disease. All diagnoses were confirmed histologically. Additionally, the PET FDG technique detected extrathoracic metastases in 4 of 16 patients. Thoracic CT was not diagnostic of neoplasm in two of the eight patients with bronchogenic carcinomas. In one patient with an ACTH-producing bronchial carcinoid, the lesion ultimately was detected on high-resolution CT but was not metabolically active on PET FDG imaging. CONCLUSIONS: This is the first report of whole-body PET FDG imaging in patients with thoracic lesions. PET FDG imaging accurately detected metabolically active tumor (both intrathoracic and extrathoracic) in patients with bronchogenic carcinoma, pulmonary metastatic disease, and Hodgkin lymphoma. Because lung cancer is characteristically a multisystem disease, this whole-body PET FDG technique has significant implications for treatment planning.

Adenocarcinoma↗
PubMed1993

An animal model for in vivo evaluation of tumor glycolytic rates with positron emission tomography.

We developed a method for evaluating tumor glycolytic rates in vivo with nude mice injected with 2-[F-18]fluoro-2-deoxy-D-glucose (FDG) and a dedicated animal positron emission tomography (PET) scanner. Animals were injected with NR-6 mouse fibroblast tumor cell lines. When tumors achieved a large enough size to be macroscopically visible, quantitative measurements of FDG uptake in vivo were obtained, using both standard nonlinear regression with the FDG tracer kinetic model to generate estimates of model parameters, including KNLR, the rate constant for net phosphorylation of FDG. Additionally, we determined the values of KPAT, the rate constant for net phosphorylation of FDG measured with a non-iterative graphical method. Estimates of K were highly correlated (r = 0.95) with both methods, and parametric images of KPAT demonstrate both the tumor location and size, but are also scaled in units of phosphorylation of FDG. The method is suitable for serial studies of tumor glucose metabolism during and after therapeutic interventions, such as chemotherapeutic trials.

Animals↗
PubMed1993

Factors affecting myocardial 2-[F-18]fluoro-2-deoxy-D-glucose uptake in positron emission tomography studies of normal humans.

The goal of this study was to identify the anatomic and physiologic factors affecting left ventricular myocardial 2-[F-18]fluoro-2-deoxy-D-glucose (FDG) uptake and myocardial glucose utilization rates (MRGlc) in normal humans. Eighteen healthy male volunteers were studied in the fasting state (4-19 h) and 16 after oral glucose loading (100 g dextrose) with positron emission tomography (PET) and FDG. Substrate and hormone concentrations were measured in each study. The kinetics of myocardial FDG uptake were evaluated using both a three-compartment model and Patlak graphical analysis. Systolic blood pressures and rate pressure products were similar in the fasting and postglucose states. MRGlc averaged 0.24 +/- 0.17 mumol/min/g in fasting subjects and rose to 0.69 +/- 0.11 mumol/min/g after glucose loading. Phosphorylation rate constant, k3, and MRGlc were linearly related (P < 0.001). Increases in MRGlc following glucose loading were correlated with plasma glucose, insulin and free fatty acid concentrations, ratios of insulin to glucagon levels, and influx rate constants of FDG. Glucose loading improved the diagnostic image quality due to more rapid clearance of tracer from blood and higher myocardial FDG uptake. When MRGlc, glucose and insulin concentrations, and insulin to glucagon ratios exceeded 0.2 mumol/min/g, 100 mg/dl, 19 microU/ml, and 0.2 microU/pg, respectively, myocardial uptake of FDG was always adequate for diagnostic use. FDG image quality and MRGlc were similar after relatively short (6 +/- 2 h) and overnight (16 +/- 2 h) fasting. Significant (P < 0.05) regional heterogeneity of myocardial FDG uptake and MRGlc was observed in both the fasting and the postglucose studies. MRGlc and FDG uptake values in the posterolateral wall were higher than those in the anterior wall and septum. Thus, both 6-h and overnight fasts resulted in similarly low myocardial glucose utilization rates. While MRGlc and myocardial FDG uptake depended on plasma glucose, free fatty acid, and insulin concentrations, the results also suggest an additional dependency on plasma glucagon levels. Regional heterogeneities in myocardial FDG uptake and MRGlc are evident and independent of the subjects' dietary state. These regional heterogeneities need to be considered in studies of patients with cardiac disease.

Adult↗
PubMed1993

Synthesis of 6-[18F] and 4-[18F]fluoro-L-m-tyrosines via regioselective radiofluorodestannylation.

The regioselective radiofluorodestannylation of 6-trimethylstannyl-L-m-tyrosine derivative 6 with [18F]F2 and [18F]acetyl hypofluorite afforded, after acid hydrolysis, 6-[18F]fluoro-L-m-tyrosine (8a) in radiochemical yields of 23 and 17%, respectively. Similarly, 4-[18F]fluoro-L-m-tyrosine (13a) was synthesized in 11% radiochemical yield from the corresponding 4-trimethylstannyl-L-m-tyrosine derivative 11 using [18F]F2. The structural analyses of precursors (6,11), intermediates, and the final products (after 18F decay), were carried out by 1H, 13C, 19F, 119Sn-NMR and high resolution mass spectroscopy.

Fluorine Radioisotopes↗
PubMed1993

Quantification and parametric imaging of renal cortical blood flow in vivo based on Patlak graphical analysis.

Patlak graphical analysis was applied to quantify renal cortical blood flow with N-13 ammonia and dynamic positron emission tomography. Measurements were made in a swine model of kidney transplantation with a wide range of normal and abnormal renal blood flows (N = 57 studies) and in 20 healthy human volunteers (N = 45 studies). Estimates of renal cortical blood flow by the Patlak method were compared to those from a two-compartment model for N-13 ammonia. In addition, estimates of renal cortical blood flow by the N-13 ammonia PET approach were compared in 10 normal human volunteers to estimates by the metabolically inert, freely diffusible O-15 water and a one-compartment model. Patlak graphical analysis estimates of renal cortical blood flow correlated linearly with the standard two-compartment model in pigs (y = -0.05 + 1.01x, r = 0.99) and in humans (y = 0.57 + 0.88x, r = 0.93). Estimates of renal cortical blood flow by O-15 water in human volunteers were also linearly correlated with those by N-13 ammonia and the Patlak graphical analysis (y = 0.71 + 0.84x, r = 0.86). Renal cortical blood flow estimates were highly reproducible both with N-13 ammonia and O-15 water measurements in humans. It is concluded that the Patlak graphical analysis with N-13 ammonia dynamic positron emission tomograpic imaging renders accurate and reproducible estimates of renal cortical blood flow. Moreover, the graphical analysis approach is 1,000 times faster than the standard model fitting approach and suitable for generating parametric images of renal blood flow in the clinical setting.

Adolescent↗
PubMed1993

[Whole body positron emission tomography in breast cancer].

The value of whole body positron emission tomography using F-18 2-deoxy-2-fluoro-d-glucose in primary work-up and follow-up was prospectively evaluated in 37 patients with primary or metastatic breast cancer. From 20 primary breast masses 15 from 16 malignant and 4 from 4 benign lesions confirmed by biopsy, were detected. In 3 out of 21 patients in correlation to morphologic imaging, respectively biopsy, no metastatic disease was not identified. Generally speaking, whole body positron emission tomography appears to be a suitable diagnostic staging tool in breast cancer.

Adenocarcinoma↗
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

Regional myocardial blood flow and glucose utilization in symptomatic patients with hypertrophic cardiomyopathy.

BACKGROUND: Previous studies suggested the presence of myocardial ischemia in symptomatic patients with hypertrophic cardiomyopathy. Positron emission tomography, a technique that can identify metabolic consequences of ischemia in coronary artery disease, permits the noninvasive measurements of regional myocardial blood flow and glucose metabolism. This new quantitative imaging approach should therefore be suitable for detecting a possible enhancement of glucose utilization in myocardium of patients with hypertrophic cardiomyopathy and thus may help to elucidate the pathomechanism of ischemia in this disease. METHODS AND RESULTS: In 13 symptomatic patients with hypertrophic cardiomyopathy, myocardial blood flow and glucose utilization were measured with intravenous N-13-ammonia and F-18 deoxyglucose at rest and, in four patients, again during supine bicycle exercise. At rest, blood flow was significantly lower in hypertrophied than in normal myocardium (0.78 +/- 0.19 versus 0.99 +/- 0.13 mL.min-1.g-1, p < 0.025), whereas rates of glucose utilization were similar (0.88 +/- 0.31 versus 0.87 +/- 0.35 mumol.min-1.g-1). With exercise, blood flow and glucose utilization failed to increase in hypertrophic and normal segments but became more heterogeneously distributed throughout the left ventricular myocardium. Blood flow-metabolism mismatches indicative of myocardial ischemia were noted in three patients at rest and in three of the four patients during exercise and were due to reduced flow in the presence of maintained glucose uptake. The discordance between flow and glucose metabolism in hypertrophied myocardium was significantly more prominent in younger than in older patients. CONCLUSIONS: Normal or even elevated rates of glucose utilization and the presence of diminished blood flow in hypertrophied relative to normal myocardium suggest the presence of myocardial ischemia in symptomatic hypertrophic cardiomyopathy. The age dependence of blood flow metabolism disparity suggests differences in the underlying pathophysiology or severity of disease.

Adult↗
PubMed1993

Influence of age and hemodynamics on myocardial blood flow and flow reserve.

BACKGROUND: Aging is associated with changes of the systolic blood pressure that may increase cardiac work and myocardial blood flow at rest and reduce the myocardial flow reserve. This might be misinterpreted as age-related impairment of the coronary vasodilator capacity. METHODS AND RESULTS: Myocardial blood flow was quantified at rest and after administration of intravenous dipyridamole in 40 healthy volunteers (12 women and 28 men) with 13N-ammonia and positron emission tomography. Eighteen of the normal subjects were less than and 22 were older than 50 years (31 +/- 9 versus 64 +/- 9 years). The resting rate-pressure product was lower in the younger than in the older subjects (6895 +/- 1070 versus 8634 +/- 1890; P < 0.01). Myocardial blood flow at rest averaged 0.76 +/- 0.17 mL.min-1.g-1 in the younger volunteers and 0.92 +/- 0.25 mL.min-1.g-1 in the older volunteers (P < 0.05). Hyperemic blood flows did not differ between younger and older subjects (3.0 +/- 0.8 versus 2.7 +/- 0.6 mL.min-1.g-1; P = NS); however, minimal coronary resistance was higher in the older subjects. Corrected for indexes of coronary driving pressure, hyperemic flow was lower in older than in younger normal subjects. The higher resting blood flows combined with similar hyperemic flows resulted in a lower myocardial flow reserve in the older than in the younger normal subjects (4.1 +/- 0.9 versus 3.0 +/- 0.70; P < 0.0001). The flow reserve was more closely correlated with resting than with hyperemic blood flows. CONCLUSIONS: Aging does not alter significantly dipyridamole-induced hyperemic flows; although coronary vascular resistance after dipyridamole was somewhat increased in older subjects. The gradual decline of the myocardial blood flow reserve correlates with an age-related increase of baseline myocardial work and blood flow. These findings suggest that the reduced flow reserve with age is primarily due to increased cardiac work and blood flow at rest rather than to an abnormal vasodilator capacity.

Adult↗
PubMed1993

Regional blood flow, oxidative metabolism, and glucose utilization in patients with recent myocardial infarction.

BACKGROUND: Metabolic imaging with positron emission tomography (PET) can detect tissue viability in clinical infarct regions. With appropriate tracer kinetic models and serial PET imaging, regional myocardial blood flow and rates of metabolism can now be quantified in patients with recent myocardial infarctions. METHODS AND RESULTS: Serial PET imaging with [13N]ammonia, [11C]acetate, and 18F-deoxyglucose was performed in 22 patients with recent infarctions to measure regional blood flow (in milliliters per gram per minute), glucose metabolism (in micromoles per gram per minute), and oxidative metabolism (in clearance rate per minute). Hypoperfused clinical infarct regions were classified as "PET mismatch" if 18F was increased relative to 13N activity or "PET match" if 13N and 18F activities were reduced concordantly. Blood flows differed significantly between normal, mismatch, and match segments (0.83 +/- 0.20, 0.57 +/- 0.20, and 0.32 +/- 0.12 mL.g-1.min-1, respectively). The relation between oxidative metabolism and blood flow was piecewise linear and differed significantly between PET mismatch and PET match. Oxidative metabolism was less severely reduced than blood flow in mismatch regions but but reduced in proportion to blood flow in match regions. There was considerable overlap of blood flows between both types of PET segments. CONCLUSIONS: Quantification of regional blood flow and substrate metabolism in postinfarction patients revealed alterations in the relation between substrate delivery and consumption demonstrated previously only in invasive animal experiments. The preserved oxidative metabolism in myocardium with PET mismatches may be ascribed to a regional increase in oxygen extraction. Such increase together with preserved glucose utilization may be the prerequisite for survival of ischemically injured myocardium.

Coronary Angiography↗
PubMed1993

Bone metabolic activity measured with positron emission tomography and [18F]fluoride ion in renal osteodystrophy: correlation with bone histomorphometry.

We evaluated the bone metabolic activity in patients with renal osteodystrophy using positron emission tomography and [18F]fluoride ion. Eight patients had secondary hyperparathyroidism (HPT), and three had low-turnover bone disease. Eleven normal subjects were also studied, and three of the eight HPT patients were reevaluated after therapy. A rate constant (K) describing the net transport of [18F] fluoride ion into a bound compartment in bone was calculated using both a three-compartment model and Patlak graphical analysis. Values of K were compared with biochemical data and with histomorphometric indices. The results indicate that K is significantly higher (P < 0.01) in HPT patients than in normal subjects and patients with low-turnover bone disease. Values of K correlated with serum alkaline phosphatase (r = 0.81) and PTH (r = 0.93) levels and with histomorphometric indices of bone formation rate (r = 0.84, P < 0.01) and eroded perimeter (r = 0.77, P < 0.05). Values of K decreased by 40 and 30%, respectively, in two patients who underwent parathyroidectomy and medical therapy. Positron emission tomography studies of bone using [18F]fluoride ion can differentiate low turnover from high turnover lesions of renal osteodystrophy and provide quantitative estimates of bone cell activity that correlate with histomorphometric data.

Adolescent↗
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↗