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PubMed2007

The role of integrated computed tomography positron-emission tomography in esophageal cancer: staging and assessment of therapeutic response.

Computed tomography (CT) and endoscopy/endoscopic ultrasonography are usually performed to initially stage patients with esophageal cancer, to determine primary tumor response, and to detect nodal and distant metastases after preoperative therapy. Positron-emission tomography (PET) with [18F]-fluoro-2-deoxy-D-glucose and integrated CT-PET are useful in the initial staging of patients with esophageal cancer as well as in the prediction of pathologic response, disease-free interval, and overall survival after preoperative therapy. Importantly, integrated CT-PET imaging decreases the number of futile attempts at surgical resection, mainly because of the detection of occult distant metastases. The following sections review the use of integrated CT-PET imaging in determining the T, N, and M descriptors of the American Joint Commission on Cancer's 2002 guidelines for pathologic and clinical staging at initial diagnosis and after chemoradiation therapy in those patients being considered for surgical resection.

Contrast Media↗
PubMed2005

Combined positron emission tomography and computed tomography for the detection of recurrent ovarian mucinous adenocarcinoma.

BACKGROUND: The role of combined positron emission tomography and computed tomography (PET-CT) in the diagnosis of recurrent ovarian mucinous adenocarcinoma is uncertain because of previous reports that PET has limited sensitivity in the detection of mucinous neoplasms. CASE: A 71-year-old white woman presented with complaints of right lower quadrant pain and a palpable adnexal mass. Physical examination and transvaginal ultrasonography revealed a 12 x 13 cm cystic mass in the left side of the pelvis. Exploratory laparotomy, optimal tumor-reductive surgery, total abdominal hysterectomy, bilateral salpingo-oophorectomy, appendectomy, and omentectomy were performed. The diagnosis was FIGO stage IIIC well-differentiated ovarian mucinous adenocarcinoma. The patient was treated with 6 cycles of carboplatin and paclitaxel. Four months after completing chemotherapy, the patient was noted to have an elevated serum CA125 level (72 U/mL), being otherwise asymptomatic. Findings on abdominal and pelvic CT were compatible with postsurgical changes. PET-CT was performed and revealed increased metabolism along the posterior aspect of the right rectus abdominis muscle and abutting the anterior wall of an adjacent loop of bowel. CONCLUSION: PET-CT may identify clinically occult recurrent ovarian mucinous adenocarcinoma.

Adenocarcinoma, Mucinous↗
PubMed2005

Combined FDG-positron emission tomography and computed tomography for the detection of ovarian cancer recurrence in an inguinal hernia sac.

BACKGROUND: Ovarian cancer recurrence presenting in an inguinal hernia sac is rare. Only 1 case of malignant ovarian cancer growing into an inguinal hernia sac has been reported in the English literature. Combined positron emission tomography (PET) and computed tomography (CT) may have a potential role in the early detection and anatomical localization of recurrent ovarian cancer. CASE REPORT: This is the first case of occult metastasis from ovarian cancer recurrence growing in a right inguinal hernia sac identified using combined FDG-PET/CT. CONCLUSION: Preoperative combined FDG-PET/CT imaging may have utility in the detection and anatomic localization of occult ovarian cancer recurrence, which may increase the likelihood of complete resection.

Female↗
PubMed2002

Impact of computed tomography-positron emission tomography fusion in staging patients with thoracic malignancies.

BACKGROUND: Positron emission tomography (PET) has been demonstrated to improve staging in patients with thoracic malignancies. This study evaluates the ability of a new imaging technique to improve the spatial resolution and accuracy of PET. METHODS: Patients with known or suspected malignancy (n = 21) who were referred for a dedicated PET scan were also evaluated with a new camera-based PET system, which uniquely allows simultaneous computed tomography (CT) and fusion of the camera-based PET images with the CT images. The dedicated PET scan was obtained 1 hour after intravenous injection of fluorodeoxyglucose. The camera-based PET imaging was fused with the CT images at approximately 2 hours after injection. The camera-based PET and CT-PET fusion images were read independently and blindly by 2 experienced observers and the presence and location of abnormalities was compared with dedicated PET scans. RESULTS: Dedicated PET identified 18 sites in the chest as abnormal. The CT-PET fusion was superior to the camera-based PET alone, concordant with the dedicated PET in 16 of 21 patients compared with 13 of 21 by camera-based PET. The lesions missed by the camera-based PET were less than 1 cm in diameter. Fused CT-PET images provided superior anatomic localization and spatial resolution compared with dedicated PET and camera-based PET. CONCLUSIONS: CT-PET fusion images were more accurate than camera-based PET alone. CT-PET fusion improves the spatial resolution compared with dedicated PET and may improve the availability and efficacy of staging of patients with thoracic malignancies.

Humans↗
PubMed2003

Usefulness of (18)F-fluorodeoxyglucose positron emission tomography to detect para-aortic lymph nodal metastasis in advanced cervical cancer with negative computed tomography findings.

OBJECTIVE: In advanced cervical cancer, it has been reported that progression-free survival is significantly related to para-aortic lymph node metastasis. Computed tomography (CT) has been widely used for clinical staging, but its sensitivity for lymph nodal metastasis is low. Therefore, this prospective study was undertaken to evaluate (18)F-fluorodeoxyglucose positron emission tomography (FDG-PET) in detecting para-aortic lymph nodal metastasis in patients with locally advanced cervical carcinoma when CT findings were negative. METHODS: Fifty women with advanced cervical cancer confined to the pelvis with negative abdominal CT findings were included in this study. After 10 mCi of FDG was administered intravenously, the abdomens were scanned by PET. Para-aortic lymph node metastases were diagnosed as present or absent according to a standardized staging procedure. RESULTS: Retroperitoneal surgical exploration revealed 14 patients with para-aortic lymph nodal metastasis. Two patients had false-negative FDG-PET findings and the other two patients had false-positive FDG-PET findings. CONCLUSION: Overall, FDG-PET imaging had a sensitivity of 85.7%, a specificity of 94.4%, and an accuracy of 92%. When abdominal CT findings are negative, the use of FDG-PET can accurately detect para-aortic lymph nodal metastatis in patients with advanced cervical cancer.

Adult↗
PubMed2001

No difference in cardiac event-free survival between positron emission tomography-guided and single-photon emission computed tomography-guided patient management: a prospective, randomized comparison of patients with suspicion of jeopardized myocardium.

OBJECTIVES: We sought to prospectively compare nitrogen-13 (13N)-ammonia/18fluorodeoxyglucose (18FDG) positron emission tomography (PET)-guided management with stress/rest technetium-99m (99mTc)-sestamibi single-photon emission computed tomography (SPECT)-guided management. BACKGROUND: Patients with evidence of jeopardized (i.e., ischemic or viable) myocardium may benefit from revascularization, whereas patients without it should be treated with drugs. Both PET and SPECT imaging have been proven to delineate jeopardized myocardium. When patient management is based on identification of jeopardized myocardium, it is unknown which technique is most accurate for long-term prognosis. METHODS: In a clinical setting, 103 patients considered for revascularization with left ventricular wall motion abnormalities and suspicion of jeopardized myocardium underwent both PET and SPECT imaging. The imaging results were used in a randomized fashion to determine management (percutaneous transluminal coronary angioplasty [PTCA], coronary artery bypass graft surgery [CABG] or drug treatment). Follow-up for cardiac events (cardiac death, myocardial infarction and revascularization) was recorded for 28 +/- 1 months. The study was designed to have a power of 80% to detect a 20% difference in the event rate between PET- and SPECT-based management. RESULTS: Management decisions in 49 patients randomized to PET (12 who had PTCA, 14 CABG and 23 drug therapy) were comparable with 54 patients randomized to SPECT (15 who had PTCA, 13 CABG and 26 drug therapy). In terms of cardiac event-free survival, no differences between PET and SPECT were observed (11 vs. 13 cardiac events for PET and SPECT, respectively; p = NS by the Kaplan-Meier statistic). CONCLUSIONS: No difference in patient management or cardiac event-free survival was demonstrated between management based on 13N-ammonia/18FDG PET and that based on stress/rest 99mTc-sestamibi SPECT imaging. Both techniques may be used for management of patients considered for revascularization with suspicion of jeopardized myocardium.

Aged↗
PubMed2002

Electromechanical mapping for determination of myocardial contractility and viability. A comparison with echocardiography, myocardial single-photon emission computed tomography, and positron emission tomography.

OBJECTIVE: The purpose of this study was to validate electromechanical viability parameters with combined myocardial perfusion and metabolic imaging and echocardiography. BACKGROUND: The NOGA System is a catheter-based, non-fluoroscopic, three-dimensional endocardial mapping system. This unique technique allows accurate simultaneous assessment of both local electrical activity and regional contractility. METHODS: The results of NOGA, myocardial single-photon emission computed tomography (SPECT), positron emission tomography, and echocardiography in 51 patients with coronary artery disease and a pathologic SPECT study were transcribed in a nine-segment bull's-eye projection and compared. The local shortening of normally contracting segments, as shown by echocardiography, was 9.2 +/- 5.1%, which decreased to 6.6 +/- 5.0% and 4.1 +/- 5.2% in hypokinetic and akinetic segments. The highest unipolar voltage (11.2 +/- 5.0 mV) and local shortening (8.2 +/- 5.0%) characterized normally perfused segments. Fixed perfusion defects with normal or limited 18-fluoro-2-deoxy-D-glucose uptake indicating viability had a significantly higher unipolar voltage than did scar tissue (7.25 +/- 2.7 vs. 5.0 +/- 3.1 mV, p = 0.029). CONCLUSION: Electromechanical parameters sufficiently defined the viability state of the myocardium and showed good concordance with the findings by nuclear perfusion and metabolism imaging and echocardiography. The NOGA technique provides all the relevant information immediately after coronary angiography and enables the physician to proceed with therapy in the same setting.

Aged↗
PubMed2003

Electromechanical mapping versus positron emission tomography and single photon emission computed tomography for the detection of myocardial viability in patients with ischemic cardiomyopathy.

OBJECTIVES: We compared catheter-based electromechanical mapping (NOGA system, Biosense-Webster, Haifa, Israel) with positron emission tomography (PET) and single photon emission computed tomography (SPECT) for prediction of reversibly dysfunctional myocardium (RDM) and irreversibly dysfunctional myocardium (IDM) in patients with severe left ventricular dysfunction. Furthermore, we established the optimal discriminatory value of NOGA measurements for distinction between RDM and IDM. BACKGROUND: The NOGA system can detect viable myocardium but has not been used for prediction of post-revascularization contractile function in patients with ischemic cardiomyopathy. METHODS: Twenty patients (19 males, age [mean +/- SD] 60 +/- 16 years, ejection fraction [EF] 29 +/- 6%) underwent viability testing with NOGA and PET or SPECT before revascularization. Left ventricular function was studied at baseline and six months after revascularization. RESULTS: The EF increased to 34 +/- 13% at six months (p < 0.05 vs. baseline). The 58 RDM and 57 IDM regions differed with regard to unipolar voltage amplitude (UVA) (9.2 +/- 3.9 mV vs. 7.6 +/- 4.0 mV, p < 0.05), normalized UVA (106 +/- 54% vs. 75 +/- 39%, p < 0.05), and tracer uptake (76 +/- 17% vs. 60 +/- 20%, p < 0.05). The NOGA local shortening did not distinguish between RDM and IDM (6.4 +/- 5.8% vs. 5.4 +/- 6.6%). By receiver operating characteristic curve analysis, myocardial tracer uptake had better diagnostic performance than UVA (area under curve [AUC] +/- SE: 0.82 +/- 0.04 vs. 0.63 +/- 0.05, p < 0.05) and normalized UVA (AUC +/- SE: 0.70 +/- 0.05, p < 0.05). Optimal threshold was defined as the value yielding sensitivity = specificity for prediction of RDM. Sensitivity and specificity were 59% at a UVA of 8.4 mV, 65% at a normalized UVA of 83%, and 78% at a tracer uptake of 69%. CONCLUSIONS: The NOGA system may discriminate RDM from IDM with optimal discriminatory values for UVA and normalized UVA of 8.4 mV and 83%, respectively. However, the diagnostic performance does not reach the level obtained by PET and SPECT in patients with severe heart failure.

Aged↗
PubMed1998

Attenuation-corrected 99mTc-tetrofosmin single-photon emission computed tomography in the detection of viable myocardium: comparison with positron emission tomography using 18F-fluorodeoxyglucose.

OBJECTIVES: The purpose of this study was to assess the efficacy of attenuation-corrected (AC) technetium-99m (99mTc)-tetrofosmin single-photon emission computed tomography (SPECT) in detecting viable myocardium compared to 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET). BACKGROUND: The role of 99mTc-labeled perfusion tracers in the assessment of myocardial viability remains controversial. Attenuation artifacts affect the diagnostic accuracy of SPECT images. METHODS: Twenty-four patients with coronary artery disease (mean left ventricular ejection fraction 30%) underwent resting 99mTc-tetrofosmin SPECT and FDG PET imaging. Both AC and non-attenuation-corrected (NC) SPECT images were generated. RESULTS: Using a 50% threshold for viability by FDG PET, the percentage of concordant segments of viability between 99mTc-tetrofosmin and FDG on the patient basis increased from 79.8%+/-14.0% (mean+/-SD) on the NC images to 90.8%+/-10.6% on the AC images (p=0.002). The percentage of 99mTc-tetrofosmin defect segments within PET-viable segments, an estimate for the degree of underestimation of viability, decreased from 19.8%+/-15.2% on the NC images to 9.7%+/-12.6% on the AC images (p=0.01). Similar results were obtained when a 60% threshold was used to define viability by FDG PET. When the anterior-lateral and inferior-septal regions were separately analyzed, the effect of attenuation correction was significant only in the inferior-septal region. CONCLUSIONS: The results indicate that AC 99mTc-tetrofosmin SPECT improves the detection of viable myocardium mainly by decreasing the underestimation of viability particularly in the inferior-septal region, although some underestimation/overestimation of viability may still occur even with attenuation correction.

Aged↗
PubMedDate not supplied

Attenuation correction in cardiac positron emission tomography and single-photon emission computed tomography.

Quantitation in cardiac positron emission tomography (PET) and single-photon emission computed tomography (SPECT) depends on being able to correct for several physical factors that tend to distort the data. One of the most important of these corrections is the correction for attenuation. For PET, cardiac attenuation correction is a reality, although certain problems remain to be solved. For SPECT, recent developments in gamma camera hardware and reconstruction methods have finally made it possible to attempt attenuation correction in a clinical setting. This article reviews the methods available to perform attenuation correction in both PET and SPECT, with emphasis on the commonality between the problems encountered and solutions proposed for each modality.

Heart↗
PubMed1998

A1 adenosine receptor antagonists as ligands for positron emission tomography (PET) and single-photon emission tomography (SPET).

The high affinity of 8-cyclopentyl-1,3-dipropylxanthine (CPX) for the A1 adenosine receptor (A1AR) provides a good lead for developing radioligands suitable for positron emission tomography (PET) and single-photon emission tomography (SPET). This study tested the hypothesis that the kinds of chemical modifications made in the synthesis of CPX analogues containing carbon-11, fluorine-18, or radioiodine will not alter affinity for the A1AR. This report describes the synthesis and radioligand binding assays of unlabeled CPX analogues having methyl, 2-methoxyethyl, 2-fluoropropyl, or 3-fluoropropyl substituents, respectively, at either N-1 (13a-d) or N-3 (8a-d) or an (E)-3-iodoprop-2-en-1-yl substituent at N-3 (8f). Compounds 8d,f and 13b,d antagonized the binding of [3H]CPX to the A1AR of rat brain with affinities similar to those of CPX; compound 8c was twice as potent as CPX. Analogues 8a,b and 13a were less potent than CPX, but for each the Ki of antagonism was > or = 0.5 nM. Attempts to iodinate the 8-(4-hydroxyphenyl) analogue of CPX failed, probably because the xanthine substituent strongly deactivated the phenol toward electrophilic iodination. In summary, several of the modifications of the propyl groups of CPX needed to produce ligands for imaging by PET and SPET preserve or enhance affinity for the A1AR.

Animals↗
PubMed1983

Computed tomography and positron emission transaxial tomography evaluations of normal aging and Alzheimer's disease.

Young normal subjects, old normal subjects, and patients with senile dementia of the Alzheimer's type (SDAT) were studied with both computed tomography (CT) and positron emission transaxial tomography (PETT). Increases in ventricular size with both aging and disease were measured. Regional glucose metabolic rate was not affected by age, but was markedly reduced in SDAT patients. These data indicate that in normal aging, structural brain changes may be more salient than biochemical changes. Although both structural and biochemical changes occur in SDAT, the biochemical changes are more marked. The results suggest that PETT is potentially more useful than CT in the in vivo diagnosis of SDAT.

Adult↗
PubMed2005

Initial staging of lymphoma with positron emission tomography and computed tomography.

Lymphomas represent a diverse range of diseases with manifold presentations, outlook, and therapeutic approaches. Key to the modern management of lymphoma is accurate delineation of the extent of disease. The inability of computed tomography (CT) to identify the involvement of nonenlarged nodes and its relatively poor sensitivity in the detection of extra-nodal sites of involvement limit the performance of noninvasive staging techniques. Functional imaging techniques such as Ga-67 scintigraphy have been used for many years to improve the evaluation of patients with lymphoma. While providing complementary information to CT in many clinical settings, functional imaging has never had sufficient accuracy or localizing ability to seriously challenge conventional primary staging paradigms. (18)F-Fluorodeoxyglucose positron emission tomography (FDG PET), however, has been demonstrated to have both higher sensitivity and specificity than CT in many comparative series. Now that this technology also can be performed at the same time as structural imaging in the form of hybrid PET/CT devices, clinicians are rethinking the methods used to select, plan, and monitor therapy of lymphoma patients. In our institution, FDG PET/CT has become the preferred initial staging tool for patients with lymphoma.

Humans↗
PubMed2005

Update on 18F-fluorodeoxyglucose/positron emission tomography and positron emission tomography/computed tomography imaging of squamous head and neck cancers.

This article summarizes the recent literature in (18)F-fluorodeoxyglucose/positron emission tomography (FDG-PET) imaging of head and neck cancers and extends the previous review in this area by Schöder and Yeung in the July 2004 issue of Seminars in Nuclear Medicine. Positron emission tomography/computed tomography (PET-CT) imaging is now used widely but has not been adequately evaluated for head and neck cancer. Its accuracy in initial staging is better than CT but may be similar to magnetic resonance imaging. It is not sufficiently accurate in the N0 neck to rule out nodal metastases but may be appropriate if sentinel node mapping is performed in patients with PET studies showing no nodal disease. PET imaging is beginning to be used in radiotherapy treatment planning, where it makes a significant difference by identifying malignant normal size nodes, extent of viable tumor, and distant disease. PET continues to be useful in carcinoma of unknown primary in identification of the primary site. Overall success is around 27% after all other modalities have failed. FDG-PET is being used frequently to assess response to therapy and for surveillance thereafter. The major controversy is when to image after radiotherapy or combined chemo-radiotherapy. One month seems to be too early. The ideal time seems to be 3 to 4 months to avoid both false-positive and false-negative studies. The growing use of PET-CT studies in head and neck cancer will certainly make a significant difference in the treatment and outcome in this disease.

Carcinoma, Squamous Cell↗
PubMed2006

Computed tomography angiography and computed tomography perfusion in ischemic stroke: A step-by-step approach to image acquisition and three-dimensional postprocessing.

Recent technical advances in both image acquisition and postprocessing have enabled computed tomography angiography (CTA) with computed tomography perfusion to become front-line tools for acute stroke evaluation in many institutions. This article provides a step-by-step approach to utilizing these technologies, particularly in the rapid triage of appropriate stroke patients to reperfusion therapies. The specific contrast injection, image acquisition, and 3D postprocessing protocols for high-quality CTA, currently in use at our institution, are delineated. An important point of emphasis is how preliminary angiographic and cerebral perfusion observations can be made immediately at the scanner to expedite emergent therapy. Also explored is the manner in which a dedicated 3D lab can support a high clinical volume, including a large percentage of emergent studies. An accurate yet time-efficient approach for the neuroradiologist to integrate 3D interpretation with CTA source data review is offered. Several important imaging and interpretive pitfalls in stroke CTA are illustrated.

Angiography↗
PubMed2000

18-Fluorodeoxyglucose imaging with positron emission tomography and single photon emission computed tomography: cardiac applications.

The assessment of myocardial viability has become an important aspect of the diagnostic and prognostic work-up of patients with ischemic cardiomyopathy. Although revascularization may be considered in patients with extensive viable myocardium, patients with predominantly scar tissue should be treated medically or evaluated for heart transplantation. Among the many viability tests, noninvasive assessment of cardiac glucose use (as a marker of viable tissue) with F18-fluorodeoxyglucose (FDG) is considered the most accurate technique to detect viable myocardium. Cardiac FDG uptake has traditionally been imaged with positron emission tomography (PET). Clinical studies have shown that FDG-PET can accurately identify patients with viable myocardium that are likely to benefit from revascularization procedures, in terms of improvement of left ventricular (LV) function, alleviation of heart failure symptoms, and improvement of long-term prognosis. However, the restricted availability of PET equipment cannot meet the increasing demand for viability studies. As a consequence, much effort has been invested over the past years in the development of 511-keV collimators, enabling FDG imaging with single-photon emission computed tomography (SPECT). Because SPECT cameras are widely available, this approach may allow a more widespread use of FDG for the assessment of myocardial viability. Initial studies have directly compared FDG-SPECT with FDG-PET and consistently reported a good agreement for the assessment of myocardial viability between these 2 techniques. Additional studies have shown that FDG-SPECT can also predict improvement of LV function and heart failure symptoms after revascularization. Finally, recent developments, including coincidence imaging and attenuation correction, may further optimize cardiac FDG imaging (for the assessment of viability) without PET systems.

Coronary Disease↗
PubMed2003

Positron emission tomography and single-photon emission computed tomography in substance abuse research.

Many advances in the conceptualization of addiction as a disease of the brain have come from the application of imaging technologies directly in the human drug abuser. New knowledge has been driven by advances in radiotracer design and chemistry and positron emission tomography (PET) and single-photon emission computed tomography (SPECT) instrumentation and the integration of these scientific tools with the tools of biochemistry, pharmacology, and medicine. This topic cuts across the medical specialties of neurology, psychiatry, oncology, and cardiology because of the high medical, social, and economic toll that drugs of abuse, including the legal drugs, cigarettes and alcohol, take on society. This article highlights recent advances in the use of PET and SPECT imaging to measure the pharmacokinetic and pharmacodynamic effects of drugs of abuse on the human brain.

Brain↗