Franca Chierichetti

Neuroendocrine tumor imaging: can 18F-fluorodeoxyglucose positron emission tomography detect tumors with poor prognosis and aggressive behavior?

Abstract. We evaluated the clinical value of positron emission tomography (PET) using 18 F-fluorodeoxyglucose (FDG) for neuroendocrine tumor (NET) detection. Sixteen patients with cytologically or histologically proved NETs were investigated. Patients were divided in two groups of eight patients each according to the clinicopathologic features related to prognosis: slow-growing NETs and aggressive NETs. Results of FDG tumor uptake as detected by PET were compared with computed tomography (CT) scans and with scans obtained with 111 In-octreotide scintigraphy (n= 13). Tumor FDG uptake was increased in the primary lesion of all eight aggressive NETs; the tracer was shown also in lymph nodes, liver metastases, or both in five of six of them (83%). In four cases, additional unknown tumor sites undetected by CT scan were identified. A slight positivity was found in only one of eight cases with a slow-growing NET. The overall octreotide scintiscan sensitivity was 85%, but in the aggressive NETs it failed to detect the primary lesion in two of seven cases. Uptake of the tracer in some but not all tumor lesions in the same patient was seen by both FDG-PET and octreotide scintiscans. From our limited experience 18F-FDG PET seems to be useful for identifying NETs characterized by rapid growth or aggressive behavior. Uptake of the FDG tracer by the tumor may be related to a worse prognosis. Despite the heterogeneity of tracer uptake in the various lesions of NETs with multiple tumor sites, FDG-PET was able to detect unsuspected distant metastases, contributing to better staging of advanced disease.

F-18-fluorodeoxyglucose positron emission tomography in differentiating malignant from benign pancreatic cysts: a prospective study

The differential diagnosis between benign and malignant pancreatic cystic lesions may be very difficult. We recently found that F-18-.uorodeoxyglucose positron emission tomography (18-FDG PET) was useful for the preoperative work-up of pancreatic cystic lesions. This study was undertaken to confirm these results. From February 2000 to July 2003, 50 patients with a pancreatic cystic lesion were prospectively investigated with 18-FDG PET in addition to helical computed tomography (CT) and, in some instances, magnetic resonance imaging (MRI). The validation of diagnosis was based on pathologic findings after surgery (n = 31), percutaneous biopsy (n = 4), and according to follow-up in 15 patients. The 18-FDG PET was analyzed visually and semiquantitatively using the standard uptake value (SUV). The accuracy of FDG PET and CT was determined for preoperative diagnosis of malignant cystic lesions. Seventeen patients had malignant cystic lesions. Sixteen (94%) showed increased 18-FDG uptake (SUV >2.5), including two patients with carcinoma in situ. Eleven patients (65%) were correctly identified as having malignancy by CT. Thirty-three patients had benign tumors: two patients showed increased 18-FDG uptake, and four patients showed CT findings of malignancy. Sensitivity, specificity, positive and negative predictive value, and accuracy of 18-FDG PET and CT in detecting malignant tumors were 94%, 94%, 89%, 97%, and 94% and 65%, 88%, 73%, 83%, and 80%, respectively. 18-FDG PET is accurate in identifying malignant pancreatic cystic lesions and should be used in combination with CT in the preoperative evaluation of patients with pancreatic cystic lesions. A negative result with 18-FDG PET may avoid unnecessary operation in asymptomatic or high-risk patients.

Value of 18-Fluorodeoxyglucose Positron Emission Tomography in the Management of Patients With Cystic Tumors of the Pancreas

ObjectiveTo assess the reliability of 18-fluorodeoxyglucose positron emission tomography (18-FDG PET) in distinguishing benign from malignant cystic lesions of the pancreas. Summary Background DataThe preoperative differential diagnosis of cystic lesions of the pancreas remains difficult: the most important point is to identify malignant or premalignant cysts that require resection. 18-FDG PET is a new imaging procedure based on the increased glucose metabolism by tumor cells and has been proposed for the diagnosis and staging of pancreatic cancer. MethodsDuring a 4-year period, 56 patients with a suspected cystic tumor of the pancreas underwent 18-FDG PET in addition to computed tomography scanning, serum CA 19-9 assay, and in some instances magnetic resonance imaging or endoscopic retrograde cholangiopancreatography. The 18-FDG PET was analyzed visually and semiquantitatively using the standard uptake value. The accuracy of 18-FDG PET and computed tomography was determined for preoperative diagnosis of a malignant cyst. ResultsSeventeen patients had malignant tumors. Sixteen patients (94%) showed 18-FDG uptake with a standard uptake value of 2.6 to 12.0. Twelve patients (70%) were correctly identified as having malignancy by computed tomography, CA 19-9 assay, or both. Thirty-nine patients had benign tumors: only one mucinous cystadenoma showed increased 18-FDG uptake (standard uptake value 2.6). Five patients with benign cysts showed computed tomography findings of malignancy. Sensitivity, specificity, and positive and negative predictive values for 18-FDG PET and computed tomography scanning in detecting malignant tumors were 94%, 97%, 94%, and 97% and 65%, 87%, 69%, and 85%, respectively. Conclusions18-FDG PET is more accurate than computed tomography in identifying malignant pancreatic cystic lesions and should be used, in combination with computed tomography and tumor markers assay, in the preoperative evaluation of patients with pancreatic cystic lesions. A positive result on 18-FDG PET strongly suggests malignancy and, therefore, a need for resection; a negative result shows a benign tumor that may be treated with limited resection or, in selected high-risk patients, with biopsy, follow-up, or both.

Brain positron emission tomography (PET) in chronic fatigue syndrome: preliminary data

Chronic fatigue syndrome (CFS) has been widely studied by neuroimaging techniques in recent years with conflicting results. In particular, using single-photon emission computed tomography (SPECT) and perfusion tracers, hypoperfusion has been found in several brain regions, although the findings vary across research centers. The objective of this study was to investigate brain metabolism of patients affected by CFS, using [18F]fluorine-deoxyglucose (18FDG) positron emission tomography (PET). We performed 18FDG PET in 18 patients who fulfilled the criteria of the working case definition of CFS. Twelve of the 18 patients were females; the mean age was 34 +/- 15 years (range, 15-68) and the median time from CFS diagnosis was 16 months (range, 9-138). Psychiatric diseases and anxiety/neurosis were excluded in all CFS patients. CFS patients were compared with a group of 6 patients affected by depression (according to DSM IV-R) and 6 age-matched healthy controls. The CFS patients were not taking any medication at the time of PET, and depressed patients were drug-free for at least 1 week before the PET examination. The PET images examined 22 cortical and subcortical areas. CFS patients showed a significant hypometabolism in right mediofrontal cortex (P = 0.010) and brainstem (P = 0.013) in comparison with the healthy controls. Moreover, comparing patients affected by CFS and depression, the latter group showed a significant and severe hypometabolism of the medial and upper frontal regions bilaterally (P = 0.037-0.001), whereas the metabolism of brain stem was normal. Brain 18FDG PET showed specific metabolism abnormalities in patients with CFS in comparison with both healthy controls and depressed patients. The most relevant result of our study is the brain stem hypometabolism which, as reported in a perfusion SPECT study, seems to be a marker for the in vivo diagnosis of CFS.

Tumor Relapse after Pancreatic Cancer Resection is Detected Earlier by 18-FDG PET than by CT

IntroductionPancreatic cancer recurrence is often difficult to detect by conventional imaging. Our aim was to evaluate the impact of fluorodeoxyglucose-positron emission tomography (FDG-PET) in the diagnosis of recurrent pancreatic cancer.MethodsOne-hundred thirty-eight patients were followed after resection for pancreatic cancer. Sixty-six underwent only CT and were excluded. Seventy-two patients also had FDG-PET. Recurrent patients were divided in two groups: group-1, CT positive and group 2, CT non diagnostic, FDG-PET positive. Characteristics and survival curves of the two groups were compared. Significance was set at p < 0.05.ResultsOverall, tumors recurred in 63 of 72 (87.5%) patients; two patients had a second cancer resected, thanks to FDG-PET. Tumor relapse was detected by CT in 35 patients and by FDG-PET in 61. Prognostic factors were similar in groups 1 and 2. Five out of 35 group 1 patients underwent surgery (two R0, two bypass, and one exploratory). Ten out of 28 group 2 patients underwent surgery (four R0, two R2, two bypass, and two exploratory). FDG-PET influenced treatment strategies in 32 of 72 patients (44.4%). Group 2 patients survived longer (P = 0.09), but the difference was not significant. Disease-free survival was similar in groups 1 and 2.ConclusionTumor relapse is detected earlier by FDG-PET than by CT. FDG-PET can help select the best candidates for surgical exploration, although the real benefit is still to be defined. It influences treatment strategies in a significant percentage of patients. An earlier diagnosis did not influence survival due to the lack of effective therapies.

Corticobasal Degeneration: Neuropsychological Assessment and Dopamine D2 Receptor SPECT Analysis

We report a case of clinically diagnosed corticobasal degeneration, in whom neuropsychological testing was performed along with functional imaging with IBZM SPECT. HM-PAO SPECT showed marked perfusion asymmetry in parietal cortical regions, lower to the right, contralateral to the most affected side. IBZM SPECT, which gives information about postsynaptic dopaminergic D2 receptors, showed severe reduction of tracer uptake in the right basal ganglia. Our findings suggest that a postsynaptic lesion in the basal ganglia might account for the lack of response of extrapyramidal motor symptoms to dopaminergic agonists in corticobasal degeneration.

Regional cerebral blood flow changes in patients with cirrhosis assessed with 99mTc-HM-PAO single-photon emission computed tomography: effect of liver transplantation

BACKGROUND/AIMS Previous studies showed contrasting results with regard to alterations of regional cerebral blood flow/metabolism in subjects with liver cirrhosis. The aim of the study was to extend these findings in a larger series of patients. In addition, we wanted to determine whether such alterations are reversed by successful liver transplantation. METHODS The study group comprised 23 patients with liver cirrhosis and 13 normal controls. At entry to the study, all subjects underwent a complete neurological examination, EEG recordings and SPECT scanning. The severity of liver disease was determined according to the Child-Pugh score. Fourteen patients underwent a second SPECT examination 1 year after liver transplantation. RESULTS Significant rCBF reductions, ranging from 6% to 7%, were found in the majority of the cortical regions of the whole group of patients with cirrhosis, as compared to controls. These reductions were more diffuse in patients with alcoholic liver disease, comprising almost all the assayed regions. Liver transplantation normalized cortical rCBF deficits so that postoperative perfusion indexes were superimposable on control values. However, the frontal cortex remained significantly more impaired in patients with alcoholic cirrhosis than in those with non-alcoholic cirrhosis. The differences in frontal rCBF between the two groups of patients ranged from 6 to 11%. CONCLUSIONS Liver cirrhosis was associated with rCBF defects that depend upon the etiology of liver disease and that subsided after successful liver transplantation. The frontal defects in alcoholic cirrhosis either before or after surgery may imply a neurotoxic, possibly irreversible, action of ethanol.

PET imaging with 11C-acetate in prostate cancer: a biochemical, radiochemical and clinical perspective.

PurposeIn the present study, the potential clinical role of 11C-acetate PET mainly in the differential diagnosis, in the staging and in the follow-up of prostate cancer patients is reported.MethodsEach of the above points has been accurately investigated by studying the specific biochemical and radiobiochemical behaviour of this positron emitter compound.Results and ConclusionThe imaging quality of 11C-acetate PET and its unique mechanisms of cellular uptake, make such radiotracer a powerful tool in evaluating all the steps of the prostatic cancer.

T wave normalization in infarct-related electrocardiographic leads during exercise testing for detection of residual viability : Comparison with positron emission tomography

OBJECTIVES We investigated the sensitivity and specificity of exercise-induced T wave normalization (TWN) in infarct-related electrocardiographic leads (IRLs) for detection of residual viability in the infarct area. BACKGROUND The meaning of exercise-induced TWN on IRLs is not yet well understood. Recent reports suggest that TWN during dobutamine echocardiography could indicate the presence of viable myocardium. METHODS We evaluated 40 consecutive patients with a recent acute myocardial infarction and negative T waves in at least two IRLs. All patients underwent exercise testing; positron emission tomography (PET) with nitrogen-13 ammonia and fluorine-18 fluorodeoxyglucose; and coronary angiography. RESULTS Twenty-four patients showed exercise-induced TWN: 18 at a work load < or =50 W (group la) and 6 at a work load > or =75 W (group 1b); 16 patients did not show TWN (group 2). On the PET study, viability in the infarct area was present in 17 patients (94%) from group la, in only 1 (16%) from group 1b and in 4 (25%) from group 2 (p < 0.0001). The sensitivity, specificity and diagnostic accuracy of exercise-induced TWN, in comparison with residual viability, were, respectively, 82%, 67%, 75% for TWN at every work load and 77%, 94%, 85% for TWN at a work load < or =50 W. Moreover, the sensitivity and diagnostic accuracy of TWN at the low work load were higher for anterior infarctions (87% and 88%, respectively). CONCLUSIONS Exercise-induced TWN on IRLs at low work loads is a sensitive and specific index for the presence of residual viability in the infarct area. Sensitivity and diagnostic accuracy of this sign are higher for anterior infarctions.

Three-phase bone scintigraphy pattern of loosening in uncemented hip prostheses

The three-phase bone scintigraphy pattern of loosening in uncemented hip prostheses (UHPs) has not previously been elucidated. We evaluated 28 patients with complicated UHPs who had undergone total hip arthroplasty a very long time previously (range 3–20 years, mean 8.4). All the patients were surgically reviewed: 26 UHPs were found to be loosened and two infected. Nine asymptomatic UHPs were taken as controls. The dynamic phase was invariably negative in both loosened and asymptomatic UHPs while markedly positive in the infected ones. The blood pool phase was positive to various degrees in 16 of the 26 loosened UHPs as well as in the infected UHPs, but was invariably negative in painless replacements. In the bone phase, areas of significantly (discrete to marked) increased uptake were observed in all the loosened prostheses as well as in two-thirds of the asymptomatic ones. However, the regions of the lesser trochanter and/or tip and/or shaft were involved exclusively in the case of the loosened UHPs, and diffuse periprosthetic uptake was found only with loosened or infected implants. Areas of slight methylene diphosphonate (MDP) uptake were found at every periprosthetic site and areas of discrete to marked MDP uptake were commonly found in the acetabulum and/or the greater trochanter with both loosened and painless prostheses and are thus considered to be nonspecific findings.