Comparison of diagnostic accuracy of (111)In-pentetreotide SPECT and (68)Ga-DOTATOC PET/CT: A lesion-by-lesion analysis in patients with metastatic neuroendocrine tumours.

OBJECTIVES: To compare the diagnostic accuracy of (111)In-pentetreotide-scintigraphy with (68)Ga-DOTATOC-positron emission tomography (PET)/computed tomography (CT) in patients with metastatic-neuroendocrine tumour (NET) scheduled for peptide receptor radionuclide therapy (PRRT). Incremental lesions (ILs) were defined as lesions observed on only one modality. METHODS: Fifty-three metastatic-NET-patients underwent (111)In-pentetreotide-scintigraphy (24 h post-injection; planar+single-photon emission CT (SPECT) abdomen) and whole-body (68)Ga-DOTATOC-PET/CT. SPECT and PET were compared in a lesion-by-lesion and organ-by-organ analysis, determining the total lesions and ILs for both modalities. RESULTS: Significantly more lesions were detected on (68)Ga-DOTATOC-PET/CT versus (111)In-pentetreotide-scintigraphy. More specifically, we observed 1,098 lesions on PET/CT (range: 1-105; median: 15) versus 660 on SPECT (range: 0-73, median: 9) (p<0.0001), with 439 PET-ILs (42/53 patients) and one SPECT-IL (1/53 patients). The sensitivity for PET/CT was 99.9 % (95 % CI, 99.3-100.0), for SPECT 60.0 % (95 % CI, 48.5-70.2). The organ-by-organ analysis showed that the PET-ILs were most frequently visualized in liver and skeleton. CONCLUSION: Ga-DOTATOC-PET/CT is superior for the detection of NET-metastases compared to (111)In-pentetreotide SPECT. KEY POINTS: Somatostatin receptor PET is superior to SPECT in detecting NET metastases. PET is the scintigraphic method for accurate depiction of NET tumour burden. The sensitivity of PET is twofold higher than the sensitivity of SPECT.

Molecular imaging of prostate cancer.

Prostate carcinoma is the most common non-cutaneous malignancy in males. Imaging of prostatic lesions is of great importance and aids in oncologic management and monitoring of therapy response. Particularly molecular imaging based on positron emission tomography (PET) and single photon emission computerized tomography (SPECT) has great potential. Using radio-labelled molecular probes, these approaches are highly sensitive and can provide key molecular and functional information on tumours. The identification of suitable targets based on unique genetic and biochemical features of cancer lesions is one of the core activities driving progress in molecular imaging of pathological processes. Nowadays, mainly metabolic probes are being used routinely for detection and staging of prostate cancer. The development of new specific receptor ligands and targeted probes and antibodies holds great promise to further enhance the performance of molecular imaging and to further improve the diagnosis and monitoring of prostate cancer.

Effect of creatine supplementation as a potential adjuvant therapy to exercise training in cardiac patients: a randomized controlled trial.

OBJECTIVE: To investigate the effect of oral creatine supplementation in conjunction with an exercise programme on physical fitness in patients with coronary artery disease or chronic heart failure. DESIGN: Single centre double-blind randomized placebo controlled trial. SETTING: Cardiac rehabilitation centre. SUBJECTS AND INTERVENTION: 70 (4 women) cardiac patients (age 57.5 (8.4) years) were randomized to a placebo (n = 37) or creatine (n = 33) treatment for three months. Combined aerobic endurance and resistance training (three sessions/ week) was performed during supplementation. MAIN MEASURES: Aerobic power was determined during graded bicycle testing, knee extensor peak isometric and isokinetic strength, endurance and recovery were assessed by an isokinetic dynamometer, and health related quality of life was evaluated with the SF-36 and MacNew Heart Disease questionnaires. In addition, blood samples were taken after an overnight fast and 24 hour urinary collection was performed. RESULTS: At baseline there were no significant differences between both groups. We observed main time effects for aerobic power, muscle performance, health related quality of life, high density lipoprotein cholesterol and triglycerides (pre vs post; P<0.05 for all). However, changes after training were similar between placebo group and creatine group (P>0.05). Further, no detrimental effect on renal or liver function was observed nor were there any reports of side effects. CONCLUSION: Oral creatine supplementation in combination with exercise training does not exert any additional effect on the improvement in physical performance, health related quality of life, lipid profile in patients with coronary artery disease or chronic heart failure than exercise training alone.

An unusual case of 4-aminopyridine toxicity in a multiple sclerosis patient: epileptic disorder or toxic encephalopathy?

We report the case of a 45-year old female multiple sclerosis patient, who accidentally was overdosed with 4-aminopyridine which resulted in dystonic, choreathetoid type abnormal movements in the four limbs, motoric distress, confusion and opisthotonus. There is little known about 4-aminopyridine toxicity. There are only a few reported cases ranging from mild paresthesias to tonic-clonic seizures. 4-aminopyridine enhances neuronal conduction at neuromuscular synapses and is indicated in the treatment of selected neurological disorders including multiple sclerosis (MS) and myasthenia gravis, among others.

[11C]methionine PET, histopathology, and survival in primary brain tumors and recurrence.

BACKGROUND AND PURPOSE: [(11)C]Methionine (MET) PET imaging is a sensitive technique for visualizing primary brain tumors and recurrence/progression after therapy. The aim of this study was to evaluate the relationship between the uptake of MET and histopathologic grading and to investigate the prognostic value of the tracer, in both settings. METHODS: Cerebral uptake of MET was determined in 52 patients: in 26 patients for primary staging (group A) and 26 patients with suspected brain tumor recurrence/progression after therapy (group B). Semiquantitative methionine uptake indices (UI) defined by the tumor (maximum)-to-background ratio was correlated with tumor grade and final outcome. RESULTS: Overall median survival was 34.9 months. MET showed pathologically increased uptake in 41 of 52 scans. Although a weak linear correlation between MET uptake and grading was observed (R = 0.38, P = .028), analysis of variance showed no significant differences in MET UI between tumor grades for either group A or B. Benign and grade I lesions showed significant difference in MET uptake in comparison with higher grade lesions (P = .006). Using Kaplan-Meier survival analysis, no thresholds could be found at which MET was predictive for survival. Proportional hazard regression showed that only WHO grading class (low versus high) was predictive of survival (P = .015). CONCLUSION: Interindividual MET uptake variability does not allow noninvasive grading on an individual patient basis. Moreover, there is no significant prognostic value in studying maximal methionine UI in brain tumors. The clinical use of MET should therefore be primarily focused on questions such as detection of recurrence, biopsy guidance, and radiation therapy target volume delineation.

Passage of inhaled particles into the blood circulation in humans.

BACKGROUND: Pollution by particulates has been consistently associated with increased cardiovascular morbidity and mortality. However, the mechanisms responsible for these effects are not well-elucidated. METHODS AND RESULTS: To assess to what extent and how rapidly inhaled pollutant particles pass into the systemic circulation, we measured, in 5 healthy volunteers, the distribution of radioactivity after the inhalation of "Technegas," an aerosol consisting mainly of ultrafine (99m)Technetium-labeled carbon particles (<100 nm). Radioactivity was detected in blood already at 1 minute, reached a maximum between 10 and 20 minutes, and remained at this level up to 60 minutes. Thin layer chromatography of blood showed that in addition to a species corresponding to oxidized (99m)Tc, ie, pertechnetate, there was also a species corresponding to particle-bound (99m)Tc. Gamma camera images showed substantial radioactivity over the liver and other areas of the body. CONCLUSIONS: We conclude that inhaled (99m)Tc-labeled ultrafine carbon particles pass rapidly into the systemic circulation, and this process could account for the well-established, but poorly understood, extrapulmonary effects of air pollution.

Prognostic value of positron emission tomography (PET) with fluorine-18 fluorodeoxyglucose ([18F]FDG) after first-line chemotherapy in non-Hodgkin's lymphoma: is [18F]FDG-PET a valid alternative to conventional diagnostic methods?

PURPOSE: A complete remission (CR) after first-line therapy is associated with longer progression-free survival (PFS). However, defining CR is not always easy because of the presence of residual masses. Metabolic imaging with fluorine-18 fluorodeoxyglucose ([18F]FDG) positron emission tomography (PET) offers the ability to differentiate between viable and fibrotic inactive tissue. In this study, we evaluated the value of PET in detecting residual disease and, hence, predicting relapse after first-line treatment in patients with non-Hodgkin's lymphoma (NHL). PATIENTS AND METHODS: Ninety-three patients with histologically proven NHL, who underwent a whole-body [18F]FDG-PET study after completion of first-line chemotherapy and who had follow-up of at least 1 year, were included. Persistence or absence of residual disease on PET was related to PFS using Kaplan-Meier survival analysis. RESULTS: Sixty-seven patients showed a normal PET scan after first-line chemotherapy; 56 of 67 remained in CR, with a median follow-up of 653 days. Nine of these patients with a residual mass considered as unconfirmed CR received additional radiotherapy. Only 11 of 67 patients relapsed (median PFS, 404 days). Persistent abnormal [18F]FDG uptake was seen in 26 patients, and all of them relapsed (median PFS, 73 days). Because standard restaging also suggested residual disease, 12 patients received immediate secondary treatment. In 14 of 26 patients, only PET predicted persistent disease. From these patients, relapse was proven either by biopsy (n = 8) or by progressive disease on computed tomography or magnetic resonance imaging (n = 6). CONCLUSION: Persistent abnormal [18F]FDG uptake after first-line chemotherapy in NHL is highly predictive for residual or recurrent disease. In relapsing patients, PFS was significantly shorter after a positive scan than after a negative scan.

Prognostic importance of the standardized uptake value on (18)F-fluoro-2-deoxy-glucose-positron emission tomography scan in non-small-cell lung cancer: An analysis of 125 cases. Leuven Lung Cancer Group.

PURPOSE: The amount of radio-labeled (18)F-fluoro-2-deoxy-glucose (FDG) uptake, a measurement of the increased glucose metabolism of non-small-cell lung cancer (NSCLC) cells, has recently been correlated with proliferation capacity. The Standardized Uptake Value (SUV), a semi-quantitative measurement of FDG uptake on positron emission tomography (PET) scan, could thus be of prognostic significance. PATIENTS AND METHODS: We analyzed the follow-up of 125 potentially operable NSCLC patients, previously included in three of our prospective PET protocols. Performance status, maximal tumor diameter, tumor-cell type, SUV, and final staging were analyzed for their possible association with survival. RESULTS: Sixty-five patients had stage I or II NSCLC, 37 had stage IIIA, and 23 had stage IIIB. Treatment was complete resection in 91 cases. In a univariate analysis, performance status (P =.002), stage (P =.001), tumor diameter (P =.06), tumor-cell type (P =.03), and SUV greater than 7 (P =.001) were correlated with survival. For SUV, group dichotomy with a cut-off SUV of 7 had the best discriminative value for prognosis, both in the total and surgical cohort. A multivariate Cox analysis identified performance status (P =.02), stage (P =.01), and SUV (P =.007) as important for the prognosis. In the surgical group, patients with a resected tumor less than 3 cm had an expected 2-year survival of 86%, if the SUV was below 7, and 60%, if above 7. Nearly all resected tumors larger than 3 cm had SUV's greater than 7 and an expected 2-year survival of 43%. CONCLUSION: We conclude that the FDG uptake in primary NSCLC on PET has an important prognostic value and could be complementary to other well-known factors in the decision on adjuvant treatment protocols.

Additional value of whole-body positron emission tomography with fluorine-18-2-fluoro-2-deoxy-D-glucose in recurrent colorectal cancer.

PURPOSE: To assess the additional value of the whole-body [18F]-2-fluoro-2-deoxy-D-glucose positron emission tomography (FDG-PET) scan as a staging modality complementing conventional diagnostic methods (CDM) in patients suspected of having recurrent colorectal adenocarcinoma. PATIENTS AND METHODS: In 103 patients, the discordances between FDG-PET and CDM results were identified and related to the final diagnosis obtained by histopathology or clinical follow-up (> 1 year). All FDG-PET studies were reviewed with full knowledge of the CDM findings. RESULTS: In a region-based analysis, discordances between CDM and FDG-PET findings were found in 40 of 412 regions (10%). In these, FDG-PET had additional diagnostic value in 14 of 16 locoregional, six of seven hepatic, seven of eight abdominal, and eight of nine extra-abdominal regions. In a patient-based analysis, CDM categorized a subgroup of 60 patients as having resectable recurrent disease limited to the liver (n = 37) or locoregional region (n = 23). In 13 of these patients, there were discordant FDG-PET findings, detecting additional tumor sites in nine patients and excluding disease in three patients and yielding an additional diagnostic value in 20% of the patients. A second subgroup consisted of 13 patients with inconclusive CDM findings (n = 5) or with elevated plasma carcinoembryonic antigen levels and an otherwise negative conventional work-up (n = 8). In these patients, FDG-PET results were correct in eight of nine discordances, yielding a positive additional diagnostic value in 62% of the patients. CONCLUSION: Whole-body FDG-PET can have a clear impact on the therapeutic management in the follow-up of patients with colorectal cancer.

Utility of positron emission tomography for the staging of patients with potentially operable esophageal carcinoma.

PURPOSE: A prospective study of preoperative tumor-node-metastasis staging of patients with esophageal cancer (EC) was designed to compare the accuracy of 18-F-fluoro-deoxy-D-glucose (FDG) positron emission tomography (PET) with conventional noninvasive modalities. PATIENTS AND METHODS: Seventy-four patients with carcinomas of the esophagus (n = 43) or gastroesophageal junction (n = 31) were studied. All patients underwent attenuation-corrected FDG-PET imaging, a spiral computed tomography (CT) scan, and an endoscopic ultrasound (EUS). RESULTS: FDG-PET demonstrated increased activity in the primary tumor in 70 of 74 patients (sensitivity: 95%). False-negative PET images were found in four patients with T1 lesions. Thirty-four patients (46%) had stage IV disease. FDG-PET had a higher accuracy for diagnosing stage IV disease compared with the combination of CT and EUS (82% v 64%, respectively; P: =.004). FDG-PET had additional diagnostic value in 16 (22%) of 74 patients by upstaging 11 (15%) and downstaging five (7%) patients. Thirty-nine (53%) of the 74 patients underwent a 2- or 3-field lymphadenectomy in conjunction with primary curative esophagectomy. In these patients, tumoral involvement was found in 21 local and 35 regional or distant lymph nodes (LN). For local LN, the sensitivity of FDG-PET was lower than EUS (33% v 81%, respectively; P: =.027), but the specificity may have been higher (89% v 67%, respectively; P: = not significant [NS]). For the assessment of regional and distant LN involvement, compared with the combined use of CT and EUS, FDG-PET had a higher specificity (90% v 98%, respectively; P: =. 025) and a similar sensitivity (46% v 43%, respectively; P: = NS). CONCLUSION: PET significantly improves the detection of stage IV disease in EC compared with the conventional staging modalities. PET improves diagnostic specificity for LN staging.

Lymph node staging in non-small-cell lung cancer with FDG-PET scan: a prospective study on 690 lymph node stations from 68 patients.

PURPOSE: To compare the accuracy of computed tomography-(CT) scan and the radiolabeled glucose analog 18F-fluoro-2-deoxy-D-glucose (FDG) positron emission tomography (PET) visually correlated with CT (PET + CT) in the locoregional lymph node (LN) staging of non-small-cell lung cancer (NSCLC). PATIENTS AND METHODS: Sixty-eight patients with potentially operable NSCLC underwent thoracic CT, PET, and invasive surgical staging (ISS). Imaging studies were read prospectively and blinded to the surgical and pathologic data. A five-point visual scale was used for the interpretation of LNs on PET. Afterwards, with knowledge of the pathology, the relationship between standardized uptake values (SUVs) and the presence of metastasis in LNs was explored in a receiver operating characteristic (ROC) analysis, and the likelihood ratios (LRs) for SUVs of LNs were determined. RESULTS: ISS was available for 690 LN stations. CT correctly identified the nodal stage in 40 of 68 patients (59%), with understaging in 12 patients and overstaging in 16 patients. PET + CT was accurate in 59 patients (87%), with understaging in five patients and overstaging in four patients. In the detection of locally advanced disease (N2/N3), the sensitivity, specificity, and accuracy of CT were 75%, 63%, and 68%, respectively. For PET + CT, this was 93%, 95%, and 94% (P = .0004). In the ROC curve, the best SUV threshold to distinguish benign from malignant LNs was 4.40. The analysis with this SUV threshold was not superior to the use of a five-point visual scale. The LR of a SUV less than 3.5 in an LN was 0.152; for a SUV between 3.5 and 4.5, it was 3.157; and for a SUV greater than 4.5, it was 253.096. CONCLUSION: PET + CT is significantly more accurate than CT alone in LN staging of NSCLC. A five-point visual scale is as accurate as the use of an SUV threshold for LNs in the distinction between benign and malignant nodes. The very high negative predictive value of mediastinal PET could reduce the need for mediastinal ISS in NSCLC substantially.

Short-term effects of early intravenous treatment with a beta-adrenergic blocking agent or a specific bradycardiac agent in patients with acute myocardial infarction receiving thrombolytic therapy.

OBJECTIVES: This study was conducted to explore mechanisms that could explain the possible clinical benefit of early administration of a beta 1-selective adrenoreceptor blocking agent or a bradycardiac drug as adjunct to thrombolysis in acute myocardial infarction. BACKGROUND: The effects of beta-blockers given concomitantly with thrombolytic therapy in patients with acute myocardial infarction have not been fully examined. The potential role of specific bradycardiac agents lacking negative inotropism as an alternative to beta-blockers in this setting has never been studied in humans. METHODS: In a double-blind study, we examined the effects of early intravenous and continued oral administration of a beta-blocker (atenolol), a specific bradycardiac agent (alinidine) or placebo on left ventricular function, late coronary artery patency, infarct size, exercise capacity and incidence of arrhythmias. RESULTS: A total of 292 patients with acute myocardial infarction of < or = 5 h duration and without contraindications to thrombolytic or beta-blocker therapy were studied. Of these, 100 were allocated to treatment with atenolol (5 to 10 mg intravenously followed by 25 to 50 mg orally every 12 h), 98 to alinidine (20 to 40 mg intravenously followed by 20 to 40 mg orally every 8 h) and 94 to placebo. All patients received 100 mg of alteplase over 3 h and full intravenous heparinization. No significant differences in coronary artery patency, global ejection fraction or regional wall motion were observed at 10 to 14 days among the three groups. Likewise, enzymatic and scintigraphic infarct size were also very similar. Neither atenolol nor alinidine was associated with a significant reduction in the incidence of arrhythmias during the 1st 24 h. No significant differences in clinical events were observed, with the exception of a greater incidence of nonfatal pulmonary edema in the atenolol group (6% vs. 1% in the alinidine group and 0% in the placebo group, p = 0.021). CONCLUSIONS: In the absence of contraindications, the administration of a beta-blocker or a specific bradycardiac agent together with thrombolytic therapy was safe. In this limited number of patients, these agents did not appear to enhance myocardial salvage or preservation of left ventricular function or to reduce the incidence of major arrhythmias in the early phase of infarction.

Early assessment of regional myocardial blood flow and metabolism in thrombolysis in myocardial infarction flow grade 3 reperfused myocardial infarction using carbon-11-acetate.

OBJECTIVES: The aim of this study was to investigate the prognostic value of carbon-11-acetate (acetate) positron emission tomography (PET) after successful reperfusion of myocardial infarction (MI). BACKGROUND: Acetate PET allows the measurement of both myocardial flow and oxidative metabolism. The prognostic value of acetate measurements performed early (within 24 h) after Thrombolysis In Myocardial Infarction (TIMI) flow grade 3 reperfused MI is unknown. METHODS: In 18 patients with TIMI flow grade 3 reperfusion of their first MI, a dynamic acetate study was performed within 24 h of the acute event. At five days, nitrogen-13-NH3 (NH3) and fluorine-18-labeled fluorodeoxyglucose (FDG) PET studies were performed. Infarct-related areas were classified as "PET viable" or "PET nonviable," as assessed with NH3 and FDG, according to previously established criteria. At five days and three months, radionuclide angiography was performed for evaluation of left ventricular (LV) function. RESULTS: In infarct-related regions, myocardial blood flow, FDG uptake and oxygen consumption were decreased, compared with remote regions. However, oxygen consumption values, as measured with acetate in both PET-viable and PET-nonviable areas, as assessed with NH3 and FDG, were not significantly different (p = NS). A significant linear correlation was observed between global LV ejection fraction at three months and oxidative metabolism in the infarct-related area (r = 0.8, p < 0.0001). Multivariate analysis revealed that oxidative metabolism measurements in reperfused myocardium was the only significant predictor for recovery of LV function at three months (p < 0.05). CONCLUSIONS: Measurement of oxidative metabolism early after TIMI flow grade 3 reperfusion of MI offers important prognostic value concerning LV function at follow-up.

Assessment of myocardial viability in chronic coronary artery disease using technetium-99m sestamibi SPECT. Correlation with histologic and positron emission tomographic studies and functional follow-up.

OBJECTIVES: The value of 99mTc-sestamibi (2-methoxy-isobutyl isonitrile [MIBI]) as a viability tracer was investigated in patients undergoing coronary artery bypass graft surgery. BACKGROUND: Initial studies claim that rest MIBI single-photon emission computed tomographic (SPECT) studies can be used to assess myocardial viability. METHODS: Thirty patients with a severely stenosed left anterior descending coronary artery and wall motion abnormalities were prospectively included. The patients underwent a MIBI rest study, a positron emission tomographic (PET) flow (13NH3) and metabolism (18F-deoxyglucose) study and nuclear angiography before undergoing bypass surgery. A preoperative transmural biopsy specimen was taken from the left ventricular anterior wall. Morphometry was performed to assess percent fibrosis. After 3 months, radionuclide angiography was repeated. RESULTS: Statistically significant higher MIBI values were found in the group with myocardial viability as assessed by PET than in the group with PET-assessed nonviability (p < 0.01). Significantly higher MIBI values were found in the group with enhanced contractility at 3 months (76 +/- 13% vs. 53 +/- 22%, p < 0.01). A linear relation was found between MIBI uptake and percent fibrosis in the biopsy specimen (r = 0.78, p < 0.00001). When maximizing the threshold for assessment of viability with MIBI by using functional improvement as the reference standard, a cutoff value of 50% was found, with positive and negative predictive values of 82% and 78%, respectively. CONCLUSIONS: 99mTc MIBI uptake was significantly higher in PET-assessed viable areas and in regions with enhanced contractility at 3 months. A linear relation was found between percent fibrosis and MIBI uptake. An optimal threshold of 50% was found for prediction of functional recovery.

Colloid carcinoma arising in an anorectal fistula in Crohn's disease: a case report.

Carcinoma arising in a chronic anorectal fistula in Crohn's disease is rare, but the association has been reported in the literature. In most cases, it concerns a colloid carcinoma. Probably chronic irritation at either end of a fistula can trigger the degeneration of scar tissue into cancer. The diagnosis is difficult, due to lack of specificity of symptoms and signs, and is often delayed, resulting in a poor prognosis. A 70-year-old female, diagnosed with Crohn's disease at the age of 45, developed a pararectal colloid carcinoma in an anorectal fistula that had existed for years. She was treated with an abdominoperineal resection and adjuvant chemotherapy (5-fluorouracil and levofolinate) but died. A high index of suspicion and regular surveillance is recommended in chronic anorectal fistulas in Crohn's disease. In case of doubt, repeated biopsies should be performed to rule out malignancy.

Self-injection ictal SPECT during partial seizures.

The authors compared ictal SPECT injection performed by medical personnel with self-injection ictal SPECT in six patients with refractory temporal lobe epilepsy. Self-injection was safe and started faster. Self-injection subtraction ictal SPECT coregistered to MRI (SISCOM) was localizing in three patients who had a complex partial seizure, but only one of three patients who had a simple partial seizure, which may limit its usefulness in clinical practice. The localizing information of self-injection was better in three patients, and obviated the need for depth-EEG studies in one patient.

Unexplained rising carcinoembryonic antigen (CEA) in the postoperative surveillance of colorectal cancer: the utility of positron emission tomography (PET).

The aim of the study was to evaluate the use of positron emission tomography with [18F]-fluorodeoxyglucose (FDG-PET) in patients with unexplained rising carcinoembryonic antigen (CEA) in the postoperative surveillance of colorectal cancer. 50 consecutive patients with elevated CEA levels and a completely normal (n=31) or equivocal (n=19) conventional diagnostic work-up (CDW) were retrospectively selected. All PET images were reviewed with full knowledge of the CDW. The gold standard consisted of histology, or clinical follow-up of more than 1 year. Recurrent disease was established in 56 lesions in 43 patients. On a patient-based analysis, the sensitivity of FDG-PET was 34/43 (79%), and the positive predictive value 34/38 (89%). In 14/50 patients (28%), the FDG-PET findings led to a surgical resection with curative intent. On a lesion-based analysis, FDG-PET detected 42/56 lesions (sensitivity: 75%), the positive predictive value was 79% (42/53). These results demonstrate that FDG-PET can have a clear impact on patient management in patients with an unexplained elevation in CEA levels.

18FDG-Positron emission tomography for the early prediction of response in advanced soft tissue sarcoma treated with imatinib mesylate (Glivec).

Imatinib mesylate (Glivec, formerly STI571) is the first effective systemic treatment for gastrointestinal stromal tumours (GISTs). Major changes in tumour volume, however, tend to occur late after the start of treatment. The aim of this study was to evaluate if [18F]-fluorodeoxyglucose-positron emission tomography (FDG-PET) can be used for the early evaluation of response to imatinib mesylate treatment in soft-tissue sarcomas (STS). 21 patients (17 GIST, 4 other STS) underwent FDG-PET imaging prior to and 8 days after the start of treatment. PET response (European Organization for Research and Treatment (EORTC) guidelines) was observed in 13 GISTs (11 Complete Responders, 2 partial responders. Subsequent computerised tomography (CT) response Response Evaluation Criteria in Solid Tumours (RECIST) was observed in 10 of these patients after a median follow up of 8 weeks. Stable or progressive disease was observed on PET in 8 patients and none of them achieved a response on CT. PET response was also associated with a longer progression-free survival (PFS) (92% versus 12% at 1 year, P=0.00107). We conclude that FDG-PET is an early and sensitive method to evaluate an early response to imatinib treatment.

Model-based quantification of myocardial perfusion images from SPECT.

A system for quantitative analysis of myocardial perfusion tomograms is proposed. The system starts with an automated delineation of the total left ventricle, including possible perfusion defects, to determine the mass and shape of the myocardium. Next, polar maps or bulls-eyes are computed from the delineation, which can then be compared to reference bulls-eyes to detect perfusion defects. The proposed system differs in three main aspects from currently available bulls-eye algorithms. First, radial slices are used rather than short-axis slices. In this way three-dimensional gradient information is retained, in particular near the base and the apex of the left ventricle. Moreover, the reproducibility of this method is expected to be superior, since the interactive selection of short axis slices through the left ventricle is eliminated. Second, the left ventricle is automatically delineated using a flexible computer model in order to obtain higher reproducibility. The resulting delineation contains both mass and shape information. Third, in addition to the classic count rate bulls-eye, a mass bulls-eye is computed, which contains the myocardial mass corresponding to each bulls-eye pixel. Analysis of the count rate bulls-eye reveals perfusion defects, the quantification of the defects is carried out with the mass bulls-eye.

A study of the liver-heart artifact in emission tomography.

UNLABELLED: With the introduction of 99mTc-teboroxime, a previously undocumented artifact has shown up in cardiac SPECT imaging. In the images, the uptake values near the inferior wall are lower than expected. The artifact has been reported in the literature, but an adequate explanation has not yet been provided. The high uptake of 99mTc-teboroxime in the liver has been demonstrated to be the cause of this artifact. METHODS: With simulations we show that an artifact can be reproduced by applying filtered backprojection (without corrections for attenuation) of attenuated and blurred projections. The conclusions from the simulations are validated with SPECT and PET phantom measurements. Maximum likelihood expectation maximization (ML-EM) reconstruction is applied to evaluate the effect of accurate attenuation correction. The influence of the high liver uptake on the convergence of ML-EM was also evaluated. RESULTS: The artifact results mainly when the photon attenuation during reconstruction is ignored. This results in a distorted reconstruction of the liver. These distortions affect the neighboring inferior wall of the myocardium. While the use of opposite projections reduces the effect, accurate attenuation correction nearly eliminates it. A small additional deformation is caused by the position dependence of the spatial resolution of the gamma camera. It was also noted that the presence of the liver slows down the convergence of ML-EM in the heart region. CONCLUSION: The liver-heart artifact is an attenuation effect and is eliminated by attenuation correction. The local convergence of ML-EM is affected by the total image content.