Roberto Franchi

Comparison between 68Ga-DOTA-NOC and 18F-DOPA PET for the detection of gastro-entero-pancreatic and lung neuro-endocrine tumours

Purpose18F-FDG positron emission tomography (PET) value for the assessment of neuro-endocrine tumours (NET) is limited. Preliminary studies indicate that 18F-DOPA and 68Ga-DOTA-NOC are more accurate for disease assessment and 68Ga-DOTA peptides provide additional data on receptor status that are crucial for targeted radionuclide therapy. At present, there are no comparative studies investigating their role in NET.AimThe aim of this study was to compare 68Ga-DOTA-NOC and 18F-DOPA for the evaluation of gastro-entero-pancreatic and lung neuro-endocrine tumours.Materials and methodsThirteen patients with biopsy-proven NET (gastro-entero-pancreatic or pulmonary) were prospectively enrolled and scheduled for 18F-DOPA and 68Ga-DOTA-NOC PET. PET results obtained with both tracers were compared with each other, with other conventional diagnostic procedures (CT, ultrasound) and with follow-up (clinical, imaging).ResultsThe most common primary tumour site was the pancreas (8/13) followed by the ileum (2/13), the lung (2/13) and the duodenum (1/13). The carcinoma was well differentiated in 10/13 and poorly differentiated in 3/13 cases. 68Ga-DOTA-NOC PET was positive, showing at least one lesion, in 13/13 cases while 18F-DOPA PET was positive in 9/13. On a lesions basis, 68Ga-DOTA-NOC identified more lesions than 18F-DOPA (71 vs 45), especially at liver, lung and lymph node level. 68Ga-DOTA-NOC correctly identified the primary site in six of eight non-operated cases (in five cases, the primary was surgically removed before PET), while 18F-DOPA identified the primary only in two of eight cases.ConclusionsAlthough the patients studied are few and heterogeneous, our data show that 68Ga-DOTA-NOC is accurate for the detection of gastro-entero-pancreatic and lung neuro-endocrine tumours in either the primary or metastatic site and that it offers several advantages over 18F-DOPA.

Standardized Uptake Values of 68Ga-DOTANOC PET: A Promising Prognostic Tool in Neuroendocrine Tumors

Despite the fact that several studies have been published regarding the prognostic factors of neuroendocrine tumors (NETs), there are some cases in which available data are not sufficient to predict disease progression and to define a correct therapeutic approach. To our knowledge, the role of maximum standardized uptake value (SUVmax) as a prognostic factor has never been studied in NET patients. Therefore, we prospectively investigated whether 68Ga-[1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid]-1-NaI3-octreotide (68Ga-DOTANOC) PET SUVmax could be used as an accurate noninvasive marker for disease prognosis. Methods: Forty-seven patients with NETs were studied with 68Ga-DOTANOC PET. All patients underwent a baseline visit and laboratory and radiologic examinations. Follow-up was performed in all cases. Results: SUVmax was significantly higher in patients with pancreatic NET and in those with well-differentiated NETs. Moreover, SUVmax was significantly higher in patients with an elevated expression of 2A-somatostatin receptor. During the follow-up, the disease was stable or presented a partial response in 25 patients, and in 19 cases the disease progressed. The patients with stable disease or a partial response had an SUVmax significantly higher than did those in the progressive disease group, with the best cutoff ranging from 17.9 to 19.3. At univariate and multivariate analysis, the significant positive prognostic factors were well-differentiated NET, an SUVmax of 19.3 or more, and a combined treatment with long-acting somatostatin analogs and radiolabeled somatostatin analogs. Conclusion: We demonstrated, for the first time to our knowledge, that 68Ga-DOTANOC PET SUVmax correlates with the clinical and pathologic features of NETs and is also an accurate prognostic index.

68ga-dota-noc: a new Pet tracer for evaluating patients with bronchial carcinoid

BackgroundConventional imaging techniques [computed tomography (CT), ultrasound, magnetic resonance] and somatostatin receptor scintigraphy are often insufficient to make a conclusive diagnosis of bronchial carcinoid (BC). PET is commonly used for the assessment of lung cancer but 18F-fluorodeoxyglucose, the most frequently used PET tracer, presents a low sensitivity for the detection of neuroendocrine tumours (NETs). New PET radiopharmaceuticals such as 68Ga-DOTA peptides, which directly bind to somatostatin receptors and are usually expressed on NET cell surfaces, have been reported to be superior to both morphological and somatostatin receptor scintigraphy imaging for gastroenteropancreatic NETs. However, their role in BC has never been evaluated. Our aim is to evaluate the role of 68Ga-DOTA-NOC (68Ga-labelled [1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid]-1-Nal3-octreotide) PET for the assessment of BC patients. MethodsTen patients with pathologically proven well-differentiated BC and one patient with highly suggestive CT images for BC were studied by 68Ga-DOTA-NOC PET/CT. PET findings were compared with clinical follow-up, pathology and contrast-enhanced CT findings. Results68Ga-DOTA-NOC PET/CT detected at least one lesion in nine of 11 patients and was negative in two. PET/CT and contrast-enhanced CT were discordant in eight of 11 patients, whereas in only three patients both provided similar results. PET/CT detected a higher number of lesions in five patients and excluded malignancy at sites considered positive on CT in three of 11; follow-up confirmed PET/CT findings in all patients. In PET/CT-positive patients, the mean maximal standardized uptake value was 25.9 [4.4–60.5]. On a clinical basis, PET/CT provided additional information in nine of 11 patients leading to the changes in the clinical management of three of nine patients. ConclusionPET/CT with 68Ga-DOTA-NOC was useful in BC patients because it led to a better evaluation of the extent of the disease.

Evaluation of unusual neuroendocrine tumours by means of 68Ga-DOTA-NOC PET

(18)F-FDG PET value for the assessment of neuroendocrine tumours (NET) is limited. Preliminary studies indicate that somatostatin receptor PET using (68)Ga-DOTA-peptides is more accurate for disease assessment and provide additional data on receptor status, that are crucial for targeted radionuclide therapy. At present, however, few papers investigated the role of (68)Ga-DOTA-NOC PET in NET, especially in unusual situations. The purpose of the present study was to evaluate (68)Ga-DOTA-NOC for the evaluation of NET of uncommon presentation. Patients with biopsy-proven NET were scheduled for (68)Ga-DOTA-NOC PET; we excluded from further evaluation cases with most common NET tumours (gastro-entero-pancreatic and pulmonary localization of primary lesion, MEN syndromes, medullary thyroid carcinoma, pheochromocytomas). PET results were compared with findings of conventional imaging, including CT, ultrasonography, MR and somatostatin receptor scintigraphy; finally PET results were compared with follow-up data with respect to the impact on patient management. Fourteen patients were finally enrolled; primary tumours were located at uterine level (3 cases), prostate (3 cases), ovary (1 case), kidney (1 case), breast (1 case), ear (1 case); also 3 cases of paraganglioma (at neck, abdominal and mediastinum level) and 1 case of lymphoma were included. (68)Ga-DOTA-NOC PET was positive, showing at least 1 lesion, in 6/14 cases while 5 cases turned out negative and 2 inconclusive. On a clinical basis, (68)Ga-DOTA-NOC provided additional information in comparison to conventional imaging procedures in 7/14 cases, and was considered useful in 12/14 patients, with 8 patients in which (68)Ga-DOTA-NOC PET was determinant for patients management. Although the number of patients studied is limited, our data show that (68)Ga-DOTA-NOC can be usefully applied for the evaluation of NET of uncommon presentation; in particular very promising results were obtained in paraganglioma. On the other hand, care has to be paid when studying lesions localized at sites of physiological concentration of the tracer, and in presence of inflammation.

11C-choline vs. 18F-FDG PET/CT in assessing bone involvement in patients with multiple myeloma

BackgroundMultiple Myeloma (MM) is a B cell neoplasm causing lytic or osteopenic bone abnormalities. Whole body skeletal survey (WBSS), Magnetic resonance (MR) and 18F-FDG PET/CT are imaging techniques routinely used for the evaluation of bone involvement in MM patients.AimAs MM bone lesions may present low 18F-FDG uptake; the aim of this study was to assess the possible added value and limitations of 11C-Choline to that of 18F-FDG PET/CT in patients affected with MM.MethodsTen patients affected with MM underwent a standard 11C-Choline PET/CT and an 18F-FDG PET/CT within one week. The results of the two scans were compared in terms of number, sites and SUVmax of lesions.ResultsFour patients (40%) had a negative concordant 11C-Choline and 18F-FDG PET/CT scans. Two patients (20%) had a positive 11C-Choline and 18F-FDG PET/CT scans that identified the same number and sites of bone lesions. The remaining four patients (40%) had a positive 11C-Choline and 18F-FDG PET/CT scan, but the two exams identified different number of lesions. Choline showed a mean SUVmax of 5 while FDG showed a mean SUVmax of 3.8 (P = 0.042). Overall, 11C-Choline PET/CT scans detected 37 bone lesions and 18F-FDG PET/CT scans detected 22 bone lesions but the difference was not significant (P = 0.8).ConclusionAccording to these preliminary data, 11C-Choline PET/CT appears to be more sensitive than 18F-FDG PET/CT for the detection of bony myelomatous lesions. If these data are confirmed in larger series of patients, 11C-Choline may be considered a more appropriate functional imaging in association with MRI for MM bone staging.

18F-FDG PET in mucosa-associated lymphoid tissue (MALT) lymphoma

To evaluate the sensitivity of 18-fluoro-2-deoxyglucose (18F-FDG) positron emission tomography (PET) in patients with mucosa-associated lymphoid tissue (MALT) lymphoma. A total of 32 patients with a histological diagnosis of extra-nodal MALT lymphoma were referred to the PET Centers in the last 2 years (2003 – 2004) and scanned with 18F-FDG-PET following standard procedures. Overall, the results of 50 18F-FDG-PET scans performed in either active disease state or in complete remission were reviewed. Sites of primary disease included stomach, lung, parotid, skin, orbit, mandible, esophagus and uterus. This study retrospectively enrolled 26 patients with known active disease. 18F-FDG-PET was true positive (TP) in 21/26 patients and false negative (FN) in 5/26. Sensitivity of 18F FDG-PET for extra-nodal MALT was 81%. The data show that 18FDG-PET is a useful diagnostic tool in order to stage, restage or monitor disease in patients with extra-nodal MALT lymphoma.

Role of 18F-dopa PET/CT imaging in the management of patients with 111In-pentetreotide negative GEP tumours.

PurposeTo assess whether 18F-dopa PET/CT is able to provide information relevant in changing the clinical management of patients with gastro-enteropancreatic (GEP) tumours where there is negative or inconclusive conventional radiological imaging (ultrasound (US), computed tomography (CT) and magnetic resonance imaging (MRI)) and 111In-pentetreotide scintigraphy. Materials and methodsFrom January 2005 to October 2006, 84 patients with clinical and biochemical suspicion of GEP tumours were investigated by US and CT scans, MRI and 111In-pentetreotide scintigraphy. In 13/84 (15.4%) both conventional radiological imaging and 111In-pentetreotide scintigraphy provided negative or inconclusive findings, and patients were referred for 18F-dopa PET/CT imaging. Each patient received 5.3 MBq · kg−1 18F-dopa intravenously, and imaged 60 min later using a hybrid PET/CT scanner. Results18F-dopa PET/CT detected the primary tumour in all 13 patients (size range, 7–26 mm, mean, 18 mm; SUVmax range, 2.3–16.3, mean, 5.7) and further 12 unsuspected lesions (size range, 12–23 mm, mean 17; SUVmax range 2.8–12.7, mean 4.6). Confirmation of the PET/CT findings was obtained in all patients from histopathological analysis of tissue obtained after surgery and/or biopsy. All the 18F-dopa-positive primary lesions were confirmed as being the primary tumour at histology, whereas of the other 12 unsuspected 18F-dopa-positive lesions, 11 were found to be metastatic deposits and one due to unspecific inflammation (one false positive result). Notably, the results of 18F-dopa PET/CT imaging changed the clinical management in 11/13 patients (84%). ConclusionsOur preliminary results suggest that 18F-dopa PET/CT has a promising role in GEP patients with negative or inconclusive findings at conventional radiological imaging and 111In-pentetreotide scintigraphy. The findings were helpful in biopsy guidance and played a major role in changing the management of those patients.

18F-FDG PET/CT in the assessment of carcinoma of unknown primary origin

Purpose.Metastatic cancers of unknown primary origin are characterised by a poor prognosis, with a survival rate from diagnosis of approximately 12 months. Conventional radiological imaging allows detection of 20%–27% of primary cancers, whereas the detection rate with positron emission tomography (PET) is 24%–40%. The aim of this study was to assess the role of 18F-fluorodeoxyglucose (FDG) PET/computed tomography (CT) in the identification of occult primary cancers.Materials and methods.The study population consisted of 38 consecutive patients with histologically proven metastatic disease and negative or nonconclusive conventional diagnostic procedures. All patients were studied by 18F-FDG PET performed according to the standard procedure (6 h of fasting, intravenous injection of 370 MBq 18F-FDG, and image acquisition with a PET/CT scanner for 4 min per bed position).Results.18F-FDG-PET/CT detected the occult primary cancer in 20 cases (53%), showing higher sensitivity than that reported for any other imaging modality, including PET.Conclusions.The encouraging results, if validated by larger series, support the use of PET/CT in patients with carcinoma of unknown primary origin and negative conventional imaging results.

Role of 18F-FDG PET for Evaluating Malignant Pleural Mesothelioma

Malignant Pleural Mesothelioma (MPM) is a relatively rare neoplasia characterized by a poor prognosis. Recent studies show that new therapeutic approaches can lead to an improvement in life quality and to a prolonged survival; therefore, proper evaluation of MPM before, as well as after, therapy, is needed. The aim of this study was to evaluate the impact of 18F-FDG photon emission tomography (PET) scan compared to computed tomography (CT) findings in patients affected by MPM, whether untreated or already treated. We studied 15 consecutive patients (13 male and 2 female) with a histological diagnosis of MPM, with a mean age of 69.9 years (range: 38-78 years old) and a recent total-body CT scan. Five (5) patients were studied for staging, while 10 patients were studied after therapy. An FDG PET scan was carried out 60 minutes after an intravenous (i.v.) injection of 370 MBq of 18F-FDG. For each patient, we compared the PET stage to the CT stage, and evaluated the role of PET in choosing a therapeutic approach. In 9 of 15 (60%) patients, there was no difference between the PET and the CT stage. In 2 of 15 (13%) patients, PET upstaged the disease, while in 4 of 15 (27%) patients PET downstaged MPM. According to these results, patient management was changed in 3 cases. Specifically, 1 patient was excluded from surgery, and 2 patients had different chemotherapy. These data suggest that PET is useful in the evaluation of MPM, giving additional data that can clarify doubtful CT findings, especially regarding lymph node involvement and distant lesions. In conclusion, FDG PET was found to play a worth-while role in patient management.

Retro-orbital injection is an effective route for radiopharmaceutical administration in mice during small-animal PET studies.

Background and aimSmall-animal PET is acquiring importance for pre-clinical studies. In rodents, radiotracers are usually administrated via the tail vein. This procedure can be very difficult and time-consuming as soft tissue extravasations are very frequent and tail scars can prevent repeated injections after initial failure. The aim of our study was to compare the retro-orbital (RO) versus tail vein intravenous (i.v.) administration of 18F-FDG and 11C-choline in mice for small-animal PET studies. MethodsWe evaluated four healthy female ICR CD1 mice according to the following protocol. Day 1: each animal underwent an i.v. injection of 28 MBq of 11C-choline. PET scan was performed after 10 min and 40 min. Day 2: each animal received an RO injection of 28 MBq of 11C-choline. A PET scan was performed after 10 min and 40 min. Day 3: each animal received an i.v. injection of 28 MBq of 18F-FDG. A PET scan was performed after 60 min and 120 min. Day 4: each animal received an RO injection of 28 MBq of 18F-FDG. A PET scan was performed after 60 min and 120 min. Administration and image acquisition were performed under gas anaesthesia. For FDG studies the animals fasted for 2 h and were kept asleep for 20–30 min after injection, to avoid muscular uptake. Images were reconstructed with 2-D OSEM. For each scan ROIs were drawn on liver, kidneys, lung, brain, heart brown fat and muscles, and the SUV was calculated. We finally compared choline i.v. standard acquisition to choline RO standard acquisition; choline i.v. delayed acquisition to choline RO delayed acquisition; FDG i.v. standard acquisition to FDG RO standard acquisition; FDG i.v. delayed acquisition to FDG RO delayed acquisition. ResultsThe RO injections for both 18F-FDG and 11C-choline were comparable to the intravenous injection of 18F-FDG for the standard and delayed acquisitions. ConclusionThe RO administration in mice represents a technical advantage over intravenous administration in being an easier and faster procedure. However, its use requires high specific activity while its value in peptides and other receptor-specific radiopharmaceuticals needs further assessment.