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R Edward Coleman

Publications and source records attributed to R Edward Coleman.

At least 37 records · Page 2Linked to original sources
PubMed2004

Phase 1 trial study of 131I-labeled chimeric 81C6 monoclonal antibody for the treatment of patients with non-Hodgkin lymphoma.

We report a phase 1 study of pharmacokinetics, dosimetry, toxicity, and response of (131)I anti-tenascin chimeric 81C6 for the treatment of lymphoma. Nine patients received a dosimetric dose of 370 MBq (10 mCi). Three patients received an administered activity of 1480 MBq (40 mCi), and 2 developed hematologic toxicity that required stem cell infusion. Six patients received an administered activity of 1110 MBq (30 mCi), and 2 developed toxicity that required stem cell infusion. The clearance of whole-body activity was monoexponential with a mean effective half-life of 110 hours (range, 90-136 hours) and a mean effective whole-body residence time of 159 hours (range, 130-196 hours). There was rapid uptake within the viscera; however, tumor uptake was slower. Activity in normal viscera decreased proportional to the whole body; however, tumor sites presented a slow clearance (T(1/2), 86-191 hours). The mean absorbed dose to whole-body was 67 cGy (range, 51-89 hours), whereas the dose to tumor sites was 963 cGy (range, 363-1517 cGy). Despite lack of a "blocking" antibody, 1 of 9 patients attained a complete remission and 1 a partial remission. These data demonstrate this radiopharmaceutical to be an encouraging agent for the treatment of lymphoma particularly if methods to protect the normal viscera are developed.

Animals↗
PubMed2004

Clinical applications of PET in oncology.

Positron emission tomography (PET) provides metabolic information that has been documented to be useful in patient care. The properties of positron decay permit accurate imaging of the distribution of positron-emitting radiopharmaceuticals. The wide array of positron-emitting radiopharmaceuticals has been used to characterize multiple physiologic and pathologic states. PET is used for characterizing brain disorders such as Alzheimer disease and epilepsy and cardiac disorders such as coronary artery disease and myocardial viability. The neurologic and cardiac applications of PET are not covered in this review. The major utilization of PET clinically is in oncology and consists of imaging the distribution of fluorine 18 fluorodeoxyglucose (FDG). FDG, an analogue of glucose, accumulates in most tumors in a greater amount than it does in normal tissue. FDG PET is being used in diagnosis and follow-up of several malignancies, and the list of articles supporting its use continues to grow. In this review, the physics and instrumentation aspects of PET are described. Many of the clinical applications in oncology are mature and readily covered by third-party payers. Other applications are being used clinically but have not been as carefully evaluated in the literature, and these applications may not be covered by third-party payers. The developing applications of PET are included in this review.

Breast Neoplasms↗
PubMed2004

Prospective multicenter study of axillary nodal staging by positron emission tomography in breast cancer: a report of the staging breast cancer with PET Study Group.

PURPOSE: To determine the accuracy of positron emission tomography with fluorine-18-labeled 2-fluoro-2-deoxy-d-glucose (FDG-PET) in detecting axillary nodal metastases in women with primary breast cancer. PATIENTS AND METHODS: In this prospective multicenter study, 360 women with newly diagnosed invasive breast cancer underwent FDG-PET. Images were blindly interpreted by three experienced readers for abnormally increased axillary FDG uptake. Imaging results from 308 assessable axillae were compared with axillary node pathology. RESULTS: For detecting axillary nodal metastasis, the mean estimated area under the receiver operator curve for the three readers was 0.74 (range, 0.70 to 0.76). If at least one probably or definitely abnormal axillary focus was considered positive, the mean (and range) sensitivity, specificity, and positive and negative predictive values for PET were 61% (54% to 67%), 80% (79% to 81%), 62% (60% to 64%), and 79% (76% to 81%), respectively. False-negative axillae on PET had significantly smaller and fewer tumor-positive lymph nodes (2.7) than true-positive axillae (5.1; P <.005). Semiquantitative analysis of axillary FDG uptake showed that a nodal standardized uptake value (lean body mass) more than 1.8 had a positive predictive value of 90%, but a sensitivity of only 32%. Finding two or more intense foci of tracer uptake in the axilla was highly predictive of axillary metastasis (78% to 83% positive predictive value), albeit insensitive (27%). CONCLUSION: FDG-PET has moderate accuracy for detecting axillary metastasis but often fails to detect axillae with small and few nodal metastases. Although highly predictive for nodal tumor involvement when multiple intense foci of tracer uptake are identified, FDG-PET is not routinely recommended for axillary staging of patients with newly diagnosed breast cancer.

Adult↗
PubMed2004

Therapeutic angiogenesis in chronically ischemic porcine myocardium: comparative effects of bFGF and VEGF.

BACKGROUND: Both vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF) have been used in preclinical studies to induce new blood vessel growth in ischemic cardiac muscle with promising results. However, clinical trials have been much less convincing and further work is needed. This study expands on prior work by comparing the long-term proangiogenic effects of direct intramyocardial (IM) injection of bFGF, as well as IM and intravenous (IV) VEGF in a porcine model of chronic hibernating myocardium. METHODS: Mini-swine with proximal 90% left circumflex (LCx) coronary stenosis subtending chronically ischemic, viable (hibernating) myocardium by positron emission tomography (PET) and dobutamine stress echocardiography (DSE) were randomized to IM bFGF (n = 5), IM VEGF(165) (n = 5), IV VEGF(165) (n = 5), IM vehicle (n = 5), or sham redo-thoracotomy (n = 4). The bFGF protein was administered in a total dose of 1.35 microg divided into 30 IM injections. IM VEGF(165) protein was administered in a total dose of 15 microg/kg divided into 30 injections; IV VEGF(165) was given at a dose of 50 ng. kg(-1). min(-1) for 200 minutes at three 72-hour intervals (30 microg/kg total dose). After 3 and 6 months the PET and DSE studies were repeated, and the animals were sacrificed for tissue vascular density and angiogenic protein analysis. RESULTS: Myocardial blood flow (MBF) by PET was significantly improved 3 months posttreatment in the IM bFGF and IM VEGF(165) groups, differences that were sustained at 6 months. There was no significant increase in MBF 3-months posttreatment in the IV VEGF(165) group; however, at 6 months MBF was significantly improved. No change in MBF was seen in the IM vehicle or sham groups. Regional wall motion at rest and peak stress in the LCx region demonstrated small but statistically significant improvements by 6 months in the IM bFGF and IV VEGF(165) groups only; no improvement was seen in the IM VEGF(165), IM vehicle, or sham groups. Quantitative vascular density was significantly increased in the LCx regions of all treatment groups (IM bFGF, IM VEGF(165), IV VEGF(165)) 6-months postoperatively. No significant increase in LCx region myocardial bFGF or VEGF protein levels was seen in the treated animals at 6 months. CONCLUSIONS: The IM bFGF, IM VEGF(165), and IV VEGF(165) all improve regional perfusion and vascular density 6-months posttherapy in the animal model utilized. Functional improvements were less consistent. Both bFGF and VEGF(165) may be useful therapies for improving regional perfusion in chronically ischemic myocardium, although combination therapy with additional growth factors or cellular therapies may be necessary if concomitant improvements in function are to be seen.

Animals↗
PubMed2004

Positron emission tomography with fluoro-2-deoxy-D-glucose (FDG-PET) in the staging of post transplant lymphoproliferative disorder in lung transplant recipients.

Posttransplantation lymphoproliferative disorder (PTLD) is a histologic heterogeneous disease that complicates 4 to 8% of lung transplant recipients. Disease extent is an important prognostic factor and may affect therapy. Positron emission tomography with fluoro-2-deoxy-D-glucose (FDG-PET) has proven useful for staging high-grade lymphomas but is less accurate for staging low-grade and extranodal lymphoma. This study examined our initial experience using FDG-PET imaging to stage lung transplant recipients with posttransplantation lymphoproliferative disorder. FDG can show foci of uptake, particularly in extrathoracic sites, not seen by conventional imaging, which allows more accurate staging of disease thereby yielding useful prognostic information and guiding therapy.

Fluorodeoxyglucose F18↗
PubMed2004

Outcome prediction in patients at high risk for coronary artery disease: comparison between 99mTc tetrofosmin and 99mTc sestamibi.

PURPOSE: To determine if there was any difference in the ability of physicians to predict prognosis with technetium 99m ((99m)Tc) sestamibi or (99m)Tc tetrofosmin in a large consecutive series of patients at high risk for coronary artery disease who underwent coronary angiography. MATERIALS AND METHODS: This study included 1,818 consecutive patients who underwent a rest and stress single photon emission computed tomographic (SPECT) examination with either (99m)Tc sestamibi (n = 915) or (99m)Tc tetrofosmin (n = 903) and cardiac catheterization. A clinical index was generated and consisted of clinical and demographic variables. Information concerning death, cardiovascular death, and nonfatal myocardial infarction was 93% complete during the 1.5-year study period. Cox proportional hazards models were generated to help determine the incremental contribution of SPECT sum stress score (SSS) and the imaging agent variable to the clinical index. RESULTS: Exercise was used for stress testing in 473 (52%) patients who received (99m)Tc tetrofosmin and 519 (57%) patients who received (99m)Tc sestamibi (P =.06). Cardiovascular death or myocardial infarction occurred in 130 patients. Resulting P values for chi(2) differences between models for the end points of (a) death from any cause, (b) cardiovascular death, and (c) cardiovascular death or myocardial infarction showed that SSS combined with clinical index was a significantly better model than adjusting for only baseline characteristics (P =.001, P <.001, P =.004, respectively). Incremental addition of either (99m)Tc tetrofosmin or (99m)Tc sestamibi to those models containing SSS and the clinical index did not show further significant improvement (P =.87, P =.88, and P =.26 for death from any cause, cardiovascular death, and cardiovascular death or myocardial infarction, respectively). CONCLUSION: This study shows that the type of clinically available (99m)Tc-labeled myocardial perfusion agents should not affect interpretation of results for risk stratification and prognostic assessment.

Adenosine↗
PubMed2004

[18F]fluorodeoxyglucose-positron emission tomography in patients with medulloblastoma.

OBJECTIVE: We evaluated the [(18)F]fluorodeoxyglucose (FDG) accumulation during positron emission tomography (PET) in patients with medulloblastoma and examined the relationship of intensity of uptake with patient outcome after the initial scan. METHODS: Magnetic resonance imaging and FDG-PET scans of brain and spine were used to assess FDG uptake by visual grade (qualitative analysis) and metabolic activity ratios (T(max)/G(mean) and T(max)/W(mean)). Patients were divided into two groups based on either confirmation of tumor by biopsy and/or death resulting from progressive disease after the initial FDG-PET scan (Group A) or no intervention for the suspected lesion shown on magnetic resonance imaging after the initial FDG-PET scan but currently alive without evidence of disease (Group B). RESULTS: Twenty-two patients with either recurrent (n = 21) or newly diagnosed (n = 1) medulloblastoma underwent brain (n = 18) or whole-body (n = 4) FDG-PET scans after magnetic resonance imaging evidence of suspected tumor. The median qualitative analysis was 3 (range, 0-4) in 17 Group A patients compared with 0 (range, 0-1) in 5 Group B patients (P = 0.0003). The mean T(max)/G(mean) and T(max)/W(mean) ratios for 16 Group A patients were 1.3 (range, 0.1-3.8) and 2.10 (range, 0.4-5.2), respectively, compared with 0.80 (range, 0.20-1.5) and 1.3 (range, 0.5-1.9) in 5 Group B patients (P = 0.2 for both parameters, not significant). There was a significant negative correlation between increased FDG uptake and survival. Higher qualitative analysis and T(max)/W(mean) were associated with significantly poorer 2-year overall survival after the initial scan (71% versus 15% for qualitative analysis grade of <3 versus > or =3, P = 0.001; 46% versus 0% for T(max)/W(mean) < or =2.5 versus >2.5, P = 0.004). CONCLUSION: Increased FDG uptake is observed in medulloblastoma and is correlated negatively with survival.

Adolescent↗
PubMed2003

Lexical and sublexical components of age-related changes in neural activation during visual word identification.

Positron emission tomography data (Madden, Langley, et al., 2002) were analyzed to investigate adult age differences in the relation between neural activation and the lexical (word frequency) and sublexical (word length) components of visual word identification. The differential influence of these components on reaction time (RT) for word/nonword discrimination (lexical decision) was generally similar for the two age groups, with word frequency accounting for a greater proportion of lexical decision RT variance relative to word length. The influence of word length on RT, however, was relatively greater for older adults. Activation in regions of the ventral occipito-temporal cortex was related to the RT changes associated with word frequency and length for older adults, but not for younger adults. Specifically, older adults' frequency effects were related to activation in both anterior (Brodmann's area [BA] 37) and posterior (BAs 17 and 18) regions of the occipito-temporal pathway, whereas word length effects were only associated with posterior activation (BA 17). We conclude that aging affects the neural mechanisms supporting word identification performance although behavioral measures of this ability are generally constant as a function of age.

Adult↗
PubMed2003

Depression and increased myocardial ischemic activity in patients with ischemic heart disease.

BACKGROUND: Depression is relatively common in patients with ischemic heart disease (IHD) and is associated with increased risk of mortality and morbidity. However, the mechanisms by which depression adversely affects clinical outcomes of patients with IHD are unknown. This study examined the relationship between depression and myocardial ischemia during mental stress testing and during daily living in patients with stable IHD.Methods and results The Center for Epidemiological Studies-Depression scale (CES-D) was administered to 135 patients with IHD to evaluate depressive symptoms. Radionuclide ventriculography was used to evaluate the occurrence of left ventricular wall motion abnormality (WMA) during mental stress and exercise testing. Forty-eight-hour ambulatory electrocardiography was used to assess myocardial ischemia during daily living. The mean CES-D score was 8.2 (SD 7.4, range 0-47) with a median of 7. Logistic regression models using restricted cubic splines revealed a curvilinear relation among CES-D scores and the probability of ischemia. For patients with CES-D scores 19, the relation among scores and ischemia during mental stress tended to be inversely related, but the portion of the sample is very small. Similar patterns of results were noted for CES-D scores and ischemia during daily life. CONCLUSIONS: Patients with mild to moderate depressive symptoms (CES-D scores <or=19) are more likely to exhibit myocardial ischemia during mental stress testing and during daily living. Myocardial ischemia may be one mechanism by which depression increases the risk of mortality and morbidity in patients with IHD. The observed inverse association between higher level of depressive symptoms and ischemic activity needs to be further assessed in large samples.

Activities of Daily Living↗
PubMed2003

A comparative analysis of positron emission tomography and mediastinoscopy in staging non-small cell lung cancer.

OBJECTIVES: Positron emission tomography has been demonstrated to improve the detection of distant metastases in patients with lung cancer. This study compares the efficacy of PET to mediastinoscopy in mediastinal staging of patients with non-small cell lung cancer. METHODS: Between May 1995 and May 2000, positron emission tomography was performed on 1988 patients with known or suspected non-small cell lung cancer at Duke University Medical Center. Cervical mediastinoscopy was subsequently performed in patients without demonstrable evidence of distant metastases. The efficacy of mediastinal staging was analyzed by comparing the prospective results of positron emission tomography with the histopathologic results of mediastinoscopy by nodal station. RESULTS: In this study 202 patients with non-small cell lung cancer (116 of whom were male) underwent mediastinoscopy after positron emission tomography. Of the 65 patients with positive results of positron emission tomography, only 29 patients had positive results of mediastinoscopy in the corresponding nodal station. Of the 137 patients with negative results of positron emission tomography, 16 patients were demonstrated to have N2 or N3 disease. The sensitivity, specificity, positive and negative predictive values, and accuracy for positron emission tomography were 64.4%, 77.1%, 44.6%, 88.3%, and 74.3%, respectively. Histologic findings in patients with non-small cell lung cancer and false-positive results of mediastinal positron emission tomography included granulomatous inflammation, sinus histiocytosis, and silicosis. CONCLUSIONS: Positron emission tomography neither confirms nor excludes involvement of the mediastinum in patients with non-small cell lung cancer. Cervical mediastinoscopy with lymph node biopsy remains the criterion standard for mediastinal staging.

Adult↗
PubMed2003

Iodine -131 metaiodobenzylguanidine is an effective treatment for malignant pheochromocytoma and paraganglioma.

INTRODUCTION: Iodine 131-meta-iodobenzylguanidine ((131)I-MIBG) has been applied to the palliative treatment of metastatic pheochromocytoma in small studies. We report our institutional experience for the treatment of metastatic pheochromocytoma and paraganglioma. METHODS: We performed a retrospective review of 33 patients with metastatic pheochromocytoma (n=22) and paraganglioma (n=11) treated at our institution with (131)I-MIBG over a 10-year period. RESULTS: Patients received a mean dose of 388+/-131 mCi (131)I-MIBG. Median survival after treatment was 4.7 years. Most patients experienced a symptomatic response leading to an improved survival (4.7 years vs 1.8 years, P<.01). Patients with a measurable hormone response demonstrated an increased survival in comparison to those with no response (4.7 years vs 2.6 years, P=.01). Patients who received a high dose (>500 mCi) as their initial therapy also had improved survival (3.8 years vs 2.8 years, P=.02). CONCLUSION: These data support (131)I-MIBG treatment for select patients with metastatic pheochromocytoma. In our experience, prolonged survival was best predicted by symptomatic and hormone response to (131)I-MIBG treatment. An initial dose of 500 mCi may be optimal. The benefit of (131)I-MIBG treatment for metastatic pheochromocytoma must also be weighed against its side effects.

3-Iodobenzylguanidine↗
PubMed2003

Regional brain activation in response to rectal distension in patients with irritable bowel syndrome and the effect of a history of abuse.

Previous studies have demonstrated alterations in brain response to rectal distension in patients with irritable bowel syndrome (IBS) compared to controls. Our aim was to compare regional brain activity in response to rectal balloon distension in patients with IBS and healthy controls. We studied six patients with IBS and six healthy controls. Positron emission tomography scans were obtained during rectal balloon distensions. Statistical parametric mapping and region of interest analysis were performed to identify and compare differences in regional cerebral blood flow (CBF) for each distension pressure within and between the groups of interest. In post-hoc analyses, patients with a history of sexual or physical abuse were compared to patients without abuse. In response to rectal distension, controls exhibit a greater increase in anterior cingulate cortex (ACC) activity compared to the IBS group (Z = 3.2, P = 0.001). Thalamic activity was higher in the IBS patients relative to the control group (Z = 3.3, P < 0.001). Increased ACC activity was observed in IBS patients with no history of abuse (Z = 5.2, P < 0.001) similar to controls, whereas no such increased activity was noticed in the abused group. In conclusion, this study replicates previous findings showing alterations in brain response to rectal distension in patients with IBS. The observations on the effect of abuse suggest a possible modulating role of abuse history on this brain response.

Adolescent↗
PubMed2003

Incidental detection of pigmented villonodular synovitis on FDG PET.

18 Fluorine fluorodeoxyglucose (FDG) has been used extensively in positron emission tomographic (PET) imaging for oncology. FDG is a glucose analog demonstrating enhanced uptake in the majority of malignant as well as granulomatous lesions. Although a few cases of pigmented villonodular synovitis using bone scanning agents Tl-201 chloride, Ga-67 citrate, and Tc-99m pentavalent dimercaptosuccinic acid have been published, to our knowledge FDG PET imaging of pigmented villonodular synovitis has not.

Back↗
PubMed2003

Screening for cerebral metastases with FDG PET in patients undergoing whole-body staging of non-central nervous system malignancy.

PURPOSE: To compare fluorine 18 fluorodeoxyglucose (FDG) positron emission tomography (PET) with the current standard, magnetic resonance (MR) imaging, to determine the sensitivity and specificity of FDG PET for detection of cerebral metastases and to determine the factors that may affect lesion conspicuity. MATERIALS AND METHODS: Forty patients underwent brain PET and contrast material-enhanced brain MR imaging, with a maximum of 30 days between examinations. PET and MR images were each retrospectively reviewed by two independent readers who were blinded to the clinical history and results of the other technique. Presence of metastatic disease was recorded for each modality. Sensitivity and specificity of FDG PET were determined with MR imaging as the standard. Statistical analysis was performed with the Fisher exact test and the logistic regression model. RESULTS: Sixteen patients had cerebral metastases at MR imaging, and in 12 of these, PET scans were interpreted as showing metastatic disease (in four, scans were false-negative). Twenty-four patients had no cerebral metastases at MR imaging, and 20 of these had PET scans interpreted as normal (in four, scans were false-positive). For identification of patients with cerebral metastases, FDG PET had a sensitivity of 75% (12 of 16) and a specificity of 83% (20 of 24). Thirty-eight metastatic lesions were seen at MR imaging; 23 (61%) of these were identified at PET. Size was a statistically significant factor that influenced lesion detection at PET (P <.001). CONCLUSION: Only 61% of metastatic lesions in the brain were identified at PET. In particular, detection of small lesions was difficult.

Adolescent↗
PubMed2003

Neuroimaging and early diagnosis of Alzheimer disease: a look to the future.

Alzheimer disease (AD), a progressive neurodegenerative disorder, is the most common cause of dementia in the elderly. Current consensus statements have emphasized the need for early recognition and the fact that a diagnosis of AD can be made with high accuracy by using clinical, neuropsychologic, and imaging assessments. Magnetic resonance (MR) or computed tomographic (CT) imaging is recommended for the routine evaluation of AD. Coronal MR images can be useful to document or quantify atrophy of the hippocampus and entorhinal cortex, both of which occur early in the disease process. Both volumetric and subtraction MR techniques can be used to quantify and monitor dementia progression and rates of regional atrophy. MR measures are also increasingly being used to monitor treatment effects in clinical trials of cognitive enhancers and antidementia agents. Positron emission tomography (PET) and single photon emission CT offer value in the differential diagnosis of AD from other cortical and subcortical dementias and may also offer prognostic value. In addition, PET studies have demonstrated that subtle abnormalities may be apparent in the prodromal stages of AD and in subjects who carry susceptibility genes. PET ligands are in late-stage development for demonstration of amyloid plaques, and human studies have already begun. Functional MR-based memory challenge tests are in development as well.

Alzheimer Disease↗
PubMed2003

PET studies of the influences of nicotine on neural systems in cigarette smokers.

OBJECTIVE: The effects of acute nicotine administration and smoking on brain function were investigated in two studies, with the primary goal of identifying neural systems that mediate these effects. METHOD: In study 1, 18 healthy volunteer cigarette smokers were exposed to three conditions in a single session: 1) smoking a nicotine-containing cigarette, 2) smoking a denicotinized cigarette, or 3) receiving intravenous nicotine injections in conjunction with smoking a denicotinized cigarette. In study 2, 16 subjects smoked a nicotine-containing and denicotinized cigarette in each of two sessions 2 hours after receiving the nicotinic antagonist mecamylamine (10 mg) or placebo orally. Regional cerebral blood flow (rCBF) was assessed by using the bolus (15)O-labeled water method and positron emission tomography. Subjective measures of smoking withdrawal symptoms were also collected. RESULTS: A principal-components analysis of rCBF data pooled from the two studies identified three factors consisting of frontal, striatal, and reticular systems. The amygdala was considered as a separate region of interest. Nicotine increased normalized rCBF in the left frontal region and decreased rCBF in the left amygdala. The rCBF in the right hemisphere reticular system was related to nicotine dose in an inverted-U-shaped pattern and was strongly related to self-reported craving for cigarettes and to the addiction scale of a smoking motivation questionnaire. The effects of mecamylamine on rCBF were generally opposite to those of nicotine. CONCLUSIONS: The results indicate that nicotine influences brain regions involved in arousal and reward and suggest specific functional systems that may be linked to motivationally significant aspects of tobacco dependence.

Adult↗
PubMed2003

Mammotomography with pinhole incomplete circular orbit SPECT.

UNLABELLED: Dedicated mammotomography with pinhole incomplete circular orbit (PICO) SPECT imaging of an uncompressed pendant breast was evaluated with small, very-high-stopping-power pinhole apertures. Comparisons were made with planar pinhole scintimammography. Enhanced 3-dimensional imaging performance with very-high-stopping-power apertures is thought to ultimately yield improved sensitivities for lesion detection and identification in breast disease. METHODS: Pinhole collimators made of high-density and high atomic number (184)W or depleted (238)U, with aperture diameters from 1 to 4 mm, were used to image 0.6- and 1.0-cm-diameter spherical lesions in a pendulous, uncompressed breast phantom in planar and PICO-SPECT modes. The breast was centered on the horizontal axis of rotation of an incomplete circular orbit. Lesion, breast and body, and myocardial activities (L:B:M) were included in the phantoms to simulate clinical imaging conditions with (99m)Tc (140 keV). Lesion contrasts and signal-to-noise ratios (SNRs) for all apertures were determined for near clinical acquisition times for L:B:M ratios of 12:1:20 and 7:1:25. A set of minidisks inserted in the breast phantom was scanned to determine sampling limitations at depth from the nipple. In an initial study, a patient with biopsy-confirmed breast carcinoma was injected with 960 MBq (99m)Tc-tetrofosmin and scanned 2 h later with planar pinhole and PICO-SPECT techniques. RESULTS: Overall, for PICO-SPECT imaging there were small differences in measured counting rate sensitivity (4.9%) and lesion contrast (8.8%) with larger SNR differences (20.8%) between tungsten and depleted uranium pinhole materials at this energy and these lesion sizes. Backgrounds from simulated myocardial uptake had minor contributions in all reconstructed image volumes because of the rapid sensitivity fall-off for pinhole apertures. An optimal aperture diameter between 2 and 3 mm was determined from peak SNR, indicating that these aperture sizes may have the best performance for lesions as small as 0.6 cm in diameter with activity concentration ratios of (99m)Tc similar to those currently seen in patients. Both lesions were visualized with PICO-SPECT better than with planar pinhole imaging, with respective contrast improvements >20 times the values obtained from planar imaging for the same pinholes. In the patient study, higher contrast (>6) visualization of the active tumor periphery was obtained with PICO-SPECT than with planar imaging. CONCLUSION: These results indicate that the enhanced spatial resolution of smaller apertures outweighs the loss in sensitivity in small lesion identification with PICO-SPECT. Although the imaging differences between investigated aperture types are small and some limitations to this imaging approach exist, dedicated PICO-SPECT of the breast appears to be an improved technique compared with conventional planar pinhole scintimammography. This technique provides enhanced contrast and SNR for imaging small lesions with the high-resolution pinhole apertures along with 3-dimensional localization of the lesions.

Breast↗