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Stefano Fanti

Publications and source records attributed to Stefano Fanti.

At least 19 recordsLinked to original sources
PubMed2007

A prospective comparison of 18F-fluorodeoxyglucose positron emission tomography-computed tomography, magnetic resonance imaging and whole-body planar radiographs in the assessment of bone disease in newly diagnosed multiple myeloma.

BACKGROUND AND OBJECTIVES: Bone lesions in multiple myeloma (MM) have been traditionally detected by whole body X-ray (WBXR) survey although magnetic resonance imaging (MRI) has become the gold standard for detecting MM involvement of the spine and pelvis. The aim of this study was to compare a new technique, positron emission tomography (PET) with 18F fluorodeoxyglucose (FDG) integrated with computed tomography (18F-FDG PET-CT), with MRI and WBXR for baseline assessment of bone disease in MM. DESIGN AND METHODS: We prospectively compared 18F-FDG PET-CT, MRI of the spine-pelvis and WBXR in a series of 46 patients with newly diagnosed MM. In 23 patients who received up front autologous transplantation, we also compared post-treatment PET-CT scans with MR images of the spine and pelvis. RESULTS: Overall, PET-CT was superior to planar radiographs in 46% of patients, including 19% with negative WBXR. In 30% of patients, PET-CT scans of the spine and pelvis failed to show abnormal findings in areas in which MRI revealed an abnormal pattern of bone marrow involvement, more frequently of diffuse type. In contrast, in 35% of patients PET-CT enabled the detection of myelomatous lesions in areas which were out of the field of view of MRI. By combining MRI of the spine- pelvis and 18F-FDG PET-CT, the ability to detect sites of active MM, both medullary and extramedullary, was as high as 92%. Following transplantation, 15 patients had negative PET-CT scans (including 13 with a very good partial response or at least a near complete response), but only 8 had normal MRI. INTERPRETATION AND CONCLUSIONS: MRI of the spine and pelvis still remains the gold standard imaging technique for the detection of bone marrow involvement in MM. 18F-FDG PET-CT provides additional and valuable information for the assessment of myeloma bone disease in areas not covered by MRI.

Adult↗
PubMed2006

FDG small animal PET permits early detection of malignant cells in a xenograft murine model.

PURPOSE: The administration of new anticancer drugs in animal models is the first step from in vitro to in vivo pre-clinical protocols. At this stage it is crucial to ensure that cells are in the logarithmic phase of growth and to avoid vascular impairment, which can cause inhomogeneous distribution of the drug within the tumour and thus lead to bias in the final analysis of efficacy. In subcutaneous xenograft murine models, positivity for cancer is visually recognisable 2-3 weeks after inoculation, when a certain amount of necrosis is usually already present. The aim of this study was to evaluate the accuracy of FDG small animal PET for the early detection of malignant masses in a xenograft murine model of human rhabdomyosarcoma. A second goal was to analyse the metabolic behaviour of this xenograft tumour over time. METHODS: We studied 23 nude mice, in which 7 x 10(6) rhabdomyosarcoma cells (RH-30 cell line) were injected in the dorsal subcutaneous tissues. Each animal underwent four FDG PET scans (GE, eXplore Vista DR) under gas anaesthesia. The animals were studied 2, 5, 14 and 20 days after inoculation. We administered 20 MBq of FDG via the tail vein. Uptake time was 60 min, and acquisition time, 20 min. Images were reconstructed with OSEM 2D iterative reconstruction and the target to background ratio (TBR) was calculated for each tumour. Normal subcutaneous tissue had a TBR of 0.3. Necrosis was diagnosed when one or more cold areas were present within the mass. All the animals were sacrificed and histology was available to verify PET results. PET results were concordant with the findings of necropsy and histology in all cases. RESULTS: The incidence of the tumour was 69.6% (16/23 animals); seven animals did not develop a malignant mass. Ten of the 23 animals had a positive PET scan 2 days after inoculation. Nine of these ten animals developed a tumour; the remaining animal became negative, at the third scan. The positive predictive value of the early PET scan was 90% (9/10 animals) while the negative predictive value was 46% (6/13 animals). In the whole group of animals, mean TBR increased scan by scan. There was a statistically significant difference in TBR between 2 and 20 days after inoculation. Necrosis was present at the second scan in two animals, at the third scan in six animals and at the fourth scan in 11 animals. CONCLUSION: The high positive predictive value of FDG PET 2 days after inoculation means that an animal with a first positive scan has a very high likelihood of developing a mass and can be treated at an early stage with an experimental drug. Animals negative at this point in time will never develop a mass or will eventually do so at a late phase. As 2 of the 16 (12.5%) positive animals had necrosis at the second scan, indicating a vascular mismatch, it may be argued that animals should be treated 2 days after inoculation to guarantee homogeneous vascularisation (thereby ensuring a good drug supply within the tumour) in all subjects.

Animals↗
PubMed2006

A simple Tracerlab module modification for automated on-column [11C]methylation and [11C]carboxylation.

A modification of commercial [11C]methylation module which can be implemented for both on-column [11C]methylation and [11C]carboxylation in the same automated system is described. This module configuration was applied to the solid-phase synthesis of N-[11C]methyl-choline ([11C]choline) and L-(S-methyl-[11C])methionine ([11C]methionine), using [11C]CH(3)I as methylating agent, as well as to the synthesis of [11C]acetate by [11C]carboxylation with [11C]CO2 of methylmagnesium chloride with high and reproducible radiochemical yields in short reaction time, demonstrating to be a fast and reliable tool for the production of these [11C]radiopharmaceuticals for clinical use.

Acetic Acid↗
PubMed2006

Role of 18F-FDG-PET and PET/CT imaging in thyroid cancer.

In patients affected by differentiated thyroid cancer (DTC), the lacking of 131Iodine trapping by metastatic tissue does not allow 131Iodine whole body scintigraphy to visualize matastatic spread as well as the use of 131Iodine therapy to cure such metastatic spread. Prognosis of 131Iodine-negative DTC metastasis, so-called non-functioning metastasis, is significantly worst. In these patients an early diagnosis of non-functioning metastasis and their surgical extirpation remains the optimal therapeutic approach. In this view, a high sensitive localizing imaging different form 131Iodine whole body scintigraphy is required. Ultrasonography is characterized by a relatively high sensitivity in these patients but it is highly operator-dependent and, moreover, it can be used to explore neck alone. Computed tomography (CT) scan and magnetic resonance (MR) imaging are characterized by a relatively low sensitivity even if they are useful to provide the surgeon with anatomical information of the operating basin. Various tumor-seeking radiotracers have been proposed, mainly using SPECT as 201Thallium, 99mTc-Sestamibi and 99mTc-Tetrofosmin with good results. Even more favorable results have been reported with some positron radiotracers, mainly the 18F-FDG with PET and more recently with PET/CT tomographs. The typical indication to performing with examination is the DTC patient previously treated by total thyroidectomy and 131Iodine ablative therapy, with increased serum thyroglobulin (Tg) or anti-thyroglobulin (TgAb) antibodies during follow-up but with negative 131Iodine whole body scintigraphy even obtained after high, therapeutic 131Iodine doses. Several studies in literature have reported high sensitivity (up to 85%) and specificity (up to 95%) of FDG-PET in metastatic DTC patients. The integrated PET/CT fusion imaging systems, seem able to provide some additional advantages over PET alone, mainly related to a better anatomical localization of the hypermetabolic metastatic lesions. A change in the management of DTC patients affected by non-functioning metastatic spread not visualized by other imaging techniques has been reported in 30% of patients. Lastly, the role of PET and PET/CT fusion imaging systems seem to be promising also in patients affected by medullary thyroid carcinoma (MTC), especially for the detection of neck and mediastinal lesions, with a sensitivity superior to the other currently available imaging methods, however the data reported on medullary cancer are little and further studies are needed to elucidate the preliminary promising results.

Carcinoma, Medullary↗
PubMed2006

Minimally invasive radio-guided parathyroidectomy.

We reported here the data on minimally invasive radio-guided parathyroidectomy (MIRP) in a large group of 253 patients enrolled from the whole series of 355 consecutive patients affected by primary hyperparathyroidism (P-HPT) referred to our center. On the basis of preoperative imaging including Sestamibi scintigraphy and neck ultrasound (US), 263 patients (74% of the whole series) with evidence of a solitary parathyroid adenoma (PA) and a normal thyroid gland were addressed to MIRP and in 253 (96%) of them this minimally invasive neck exploration was successfully performed. The MIRP protocol developed in our center consisted of a very low 1 mCi Sestamibi injection in the operating room a few minutes before the start of intervention, thus minimizing the radiation exposure dose to the patient and personnel. No major intraoperative complication was recorded in patients treated by MIRP and only a transient hypocalcemia in 8.5% of cases. The mean duration time for MIRP was 35 min and the mean hospital stay 1.2 days. Local anesthesia was also performed in 62 patients, 54 of whom were elderly patients with concomitant invalidating diseases contraindicating general anesthesia. No HPT relapse was observed during subsequent follow-up. The gamma probe was used also during bilateral neck exploration in the group of 92 patients excluded from MIRP. The most frequent cause of exclusion from MIRP in our series was the presence of concomitant Sestamibi avid thyroid nodules (68.5% of cases) that can give false positive results at radio-guided surgery. In conclusion, MIRP is an effective treatment in patients with a high likelihood of a solitary PA and a normal thyroid gland at scintigraphy and US so that an accurate preoperative localizing imaging is required for MIRP. A low 1 mCi Sestamibi dose appears sufficient to perform MIRP. Patients with concomitant Sestamibi avid thyroid nodules should be excluded from MIRP.

Adenoma↗
PubMed2006

Role of 18F-FDG PET/CT in the assessment of bone involvement in newly diagnosed multiple myeloma: preliminary results.

PURPOSE: Multiple myeloma (MM) is a malignant B cell and plasma cell disorder which involves the skeleton in more than 80% of patients at diagnosis. The aim of this study was to compare whole-body X-ray (WBXR), MRI and (18)F-FDG PET/CT in patients with MM. METHODS: The study population comprised 28 newly diagnosed MM patients. Findings of (18)F-FDG PET/CT were compared with those of WBXR and MRI with regard to the number and site of lesions detected. RESULTS: Comparing (18)F-FDG PET/CT and WBXR, it was found that in 16/28 pts (57%) (18)F-FDG PET/CT detected more lesions, all of which were located in the skeleton. Nine of these 16 patients had a completely negative WBXR survey. In 12/28 pts (43%) the two methods yielded equivalent findings. Comparing (18)F-FDG PET/CT and MRI, it was found that in 7/28 pts (25%), (18)F-FDG PET/CT detected more lytic bone lesions, all of which were located outside the field of view of MRI (bone lesions in six cases and a soft tissue lesion in one). In 14/28 pts (50%), (18)F-FDG PET/CT and MRI detected the same number of lesions in the spine and pelvis, while in 7/28 pts (25%) MRI detected an infiltrative pattern in the spine whereas (18)F-FDG PET/CT was negative. CONCLUSION: (18)F-FDG PET/CT appears to be more sensitive than WBXR for the detection of small lytic bone lesions, whereas it has the same sensitivity as MRI in detecting bone disease of the spine and pelvis. On the other hand, MRI may be superior to (18)F-FDG PET/CT in diagnosing an infiltrative pattern in the spine. Therefore, careful evaluation of MM bone disease at diagnosis should include both MRI of the spine and (18)F-FDG PET/CT.

Adult↗
PubMed2006

11C-methionine PET/CT in 99mTc-sestamibi-negative hyperparathyroidism in patients with renal failure on chronic haemodialysis.

PURPOSE: Scintigraphic localisation of parathyroid glands is often unsuccessful in patients with renal failure on chronic haemodialysis who have secondary hyperparathyroidism (HPT). The purpose of this study was to investigate the use of (11)C-methionine PET/CT to detect hyperfunctioning parathyroid glands in patients with renal failure on chronic haemodialysis who had (99m)Tc-sestamibi-negative HPT. METHODS: (11)C-methionine PET/CT was performed in 18 patients (11 women and 7 men, aged 42-79 years; mean age 57.8 years) on haemodialysis for renal failure (2-14 years' duration), with normo-, hypo- or hypercalcaemia and HPT not localised by either dual-tracer (99m)Tc-pertechnetate/(99m)Tc-sestamibi subtraction scans or dual-phase (99m)Tc-sestamibi scans. RESULTS: In three of ten patients with normo- or hypocalcaemic HPT there was increased (11)C-methionine accumulation in one gland. Seven of eight patients with hypercalcaemic HPT showed increased uptake: in five of these patients increased (11)C-methionine accumulation was present in one gland, while in two it was demonstrated in two glands. All patients also had high-resolution ultrasound of the neck and were treated with subtotal parathyroidectomy, leaving a remnant of the smallest of the four glands. Regardless of their size, all glands with abnormal (11)C-methionine parathyroid uptake were removed, and all demonstrated parathyroid hyperplasia. All patients developed post-parathyroidectomy hypoparathyroidism and one patient with normocalcaemic HPT relapsed 8 months after surgery. CONCLUSION: These data suggest that (11)C-methionine PET/CT may be used to identify hyperfunctioning parathyroid glands in non-primary HPT, and especially hypercalcaemic HPT, when conventional (99m)Tc-sestamibi imaging is non-localising.

Adult↗
PubMed2006

Discordant response to chemotherapy: an unusual pattern of fluoro-deoxy-D-glucose uptake in heavily pre-treated lymphoma patients.

In recent years a number of studies have been published showing strong value of positron emission tomography using 18-Fluorine 2-fluoro-deoxy-D-glucose (FDG-PET) in term of diagnosis, response to treatment, disease recurrence and prognostic indicator in early restaging. This study observed 17 patients who presented contemporary disease progression in some localizations as well as regression in others (PROG + REG pattern); this investigation assessed that this unusual pattern of FDG uptake lead to an unfavorable prognosis. Among 1280 FDG-PET scans performed between August 2003 and December 2004 on patients affected by lymphoma with suspected recurrence, attention was focused on 17 patients presenting a PROG + REG pattern. At follow-up (4 months) only 1/17 (6%) patient was in complete remission after salvage therapy, while 6/17 (35%) had stable disease and 10/17 (59%) had rapid progression of the disease. This study further strengthens the role of FDG-PET in lymphoma patients follow-up, as it can provide useful information to better differentiate those cases who may benefit from conventional treatments from others in whom additional treatment would provide avoidable toxicity.

Adult↗
PubMed2006

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.

Adult↗
PubMed2006

Radio-guided surgery of differentiated thyroid cancer using (131)I or 99mTc-Sestamibi.

The classical therapeutic approach to patients with differentiated thyroid cancer (DTC) is based on total or near-total thyroidectomy, followed by (131)I treatment and thyroid-stimulating hormone suppressive therapy. This approach allows complete cure in many patients, especially when the tumour is diagnosed at an early stage; it also allows long-term survival in patients with locoregional recurrences or distant metastases if they can be treated with (131)I. In contrast, when metastatic DTC deposits lose their ability to trap (131)I (non-functioning metastases), a worse prognosis is expected. Nevertheless, in patients with locoregional non-functioning recurrences, an early diagnosis and prompt surgical extirpation can lead to a favourable prognosis. In these cases, radical surgery is needed. This can be achieved with radio-guided surgery using a hand-held gamma probe and a tumour-seeking radiotracer to detect, intraoperatively, the smallest metastatic lesions. In this paper, we discuss the two principal techniques proposed in the literature for radio-guided surgery of non-functioning DTC metastatic recurrences, the first using high doses of (131)I and the second using low doses of 99mTc-Sestamibi.

Clinical Trials as Topic↗
PubMed2006

Long-term prognostic value of 18F-FDG PET in patients with locally advanced rectal cancer previously treated with neoadjuvant radiochemotherapy.

OBJECTIVE: The purpose of this study was to assess the prognostic value of (18)F-FDG PET performed at restaging in patients with locally advanced rectal cancer who previously underwent neoadjuvant radiochemotherapy. SUBJECTS AND METHODS: Eighty-eight patients with histologically proven rectal cancer classified at clinical TNM stages II and III were enrolled. Six weeks after radiochemotherapy completion, all patients were restaged by sonography, CT, MRI, endoscopy, and (18)F-FDG PET. Surgery was performed in all patients within 8-9 weeks from completion of radiochemotherapy. Median follow-up after surgery was 38 months (range, 6-66 months). RESULTS: The 5-year overall survival and disease-free survival were 83% and 73%, respectively. Cox multivariate analysis showed that only two parameters at restaging were independent prognostic predictors of both overall survival and disease-free survival: pathologic stage and, especially, after radiochemotherapy (18)F-FDG PET findings. The 5-year overall survival was 91% in patients with a negative PET after radiochemotherapy versus 72% in those with a positive PET (p = 0.024) after radiochemotherapy, whereas disease-free survival was 81% and 62% (p = 0.003) for those with the negative and positive PET findings, respectively. Statistical data were further enhanced when combining the pathologic stage with the (18)F-FDG PET results: 95% 5-year overall survival in the PET-negative pathologic stages 0 and I patients versus 70% in PET-positive pathologic stages II-IV patients (p = 0.001), whereas disease-free survival was 93% and 65% (p = 0.0003) for the negative and positive PETs, respectively. CONCLUSION: In patients with locally advanced rectal cancer previously treated with neoadjuvant radiochemotherapy, the combined evaluation of pathologic stage and after-radiochemotherapy (18)F-FDG PET at restaging identified a subgroup of patients characterized by good response to radiochemotherapy and a more favorable prognosis. In these patients, a conservative surgical approach might be considered.

Adenocarcinoma↗
PubMed2006

Diagnostic role of 18F-FDG PET in gastric MALT lymphoma.

BACKGROUND: The aim of the study was to evaluate the usefulness of 18F-FDG-PET in patients with gastric lymphoma, in particular those affected by mucosa-associated lymphoid tissue (MALT) type and aggressive gastric non-Hodgkin's lymphoma (NHL). MATERIAL AND METHODS: The study group consists of 15 patients with a previous diagnosis of gastric NHL referred to our PET centres in Bologna Hospital and Rovigo Hospital, Italy, in the period 2003-2004. In 9/15 patients the subsequent histological evaluation was consistent with a gastric MALT lymphoma, while aggressive gastric NHL was diagnosed in the other 6/15. PET scan was carried out in patients with known active disease in order to stage or re-stage disease prior to treatment or in patients in complete clinical remission to monitor disease during follow up. Patients were considered in complete clinical remission if free from disease for at least 8 months after chemotherapy or surgery.18F-FDG PET was performed following standard procedures. RESULTS: Overall 18F-FDG-PET was true positive in all cases of gastric MALT and non-MALT aggressive NHL with known active disease, while no pathological 18F-FDG uptake was evident in the subjects who were in complete clinical remission. The degree of 18F-FDG uptake (mean SUVmax values) in MALT lymphoma was much less intense in comparison to aggressive gastric NHL, suggesting a prognostic role of SUV calculation in gastric lymphomas. CONCLUSION: Our data demonstrate the significant accuracy of 18F-FDG-PET in detecting active disease in gastric lymphoma of both MALT and non-MALT NHL type. A higher SUV value appears to be related to a more aggressive disease.

Adult↗
PubMed2006

Significance of posture and workload in exercise renography.

BACKGROUND: Exercise-induced alteration in renal function has been described in patients with essential hypertension. The aim of our study was to assess the significance of adopting a supine posture and the degree of workload required to induce these changes in patients with essential hypertension. The second aim was to assess whether the severity of hypertension had any influence on the development of exercise related renal dysfunction. MATERIAL AND METHODS: Fifteen patients were studied (nine patients with mild and untreated hypertension and six patients with drug resistant hypertension). Exercise renography was carried out using a cycloergometer with the patient lying in supine posture and a target exercise rate of 20 bpm over baseline rate. Each patient was injected with 100 MBq of 99mTc-MAG3 and renography was carried out for 20 minutes. Renography was repeated in rest condition only when an abnormality was observed in exercise scans. RESULTS: Exercise renography was normal in 12 patients, while in 3 patients minor abnormalities were observed during exercise related to a minimal degree of pelvic dilatation. These changes remained substantially unmodified at rest. In none of the 15 patients did we find positive studies (i.e. reversible exercise induced prolongation of tracer transit caused by cortical retention). There was no difference in the results between patients with mild or severe hypertension. CONCLUSIONS: Our results are different from previous reports on exercise renography since different groups have demonstrated exercise-induced renal dysfunction in the majority of patients with essential hypertension. The main differences between our protocol and that adopted in the literature relate to posture during exercise (upright vs. supine) and degree of workload (minor in supine exercise with less workload). These differences may have contributed to our results but further and larger studies are required to address the pathophysiological basis of exercise-induced alteration in renal function in association with essential hypertension.

Adult↗
PubMed2005

18F-FDG PET in malignant lymphoma: significance of positive findings.

PURPOSE: The aim of this study was to evaluate the significance of increased uptake of 18F-fluorodeoxyglucose (FDG) in patients with malignant lymphoma (ML) studied by positron emission tomography (PET). METHODS: A total of 1,120 consecutive scans carried out in 848 patients were reviewed; all patients had a diagnosis of ML [574 non-Hodgkin's lymphoma (NHL) and 274 Hodgkin's disease (HD)] and were studied at completion of therapy, for suspected recurrence or during follow-up. PET was carried out after intravenous injection of 370 MBq of 18F-FDG; images were recorded after 60-90 min. Patients were selected whose reports indicated areas of increased FDG uptake. PET findings were considered positive for lymphomatous localisation when uptake occurred at sites of previous disease, in asymmetrical lymph nodes or in nodes unlikely to be affected by inflammation (mediastinal, except for hilar, and abdominal). PET findings were adjudged negative for neoplastic localisations in the following instances: physiological uptake (urinary, muscular, thymic or gastrointestinal in patients without MALT), symmetrical nodal uptake, uptake in lesions unrelated to lymphoma that had already been identified by other imaging methods at the time of PET scan, uptake at sites atypical for lymphoma, very low uptake and non-focal uptake. PET findings were compared with the results of other diagnostic procedures (including CT and ultrasound), biopsy findings and follow-up data. RESULTS: Overall, 354 scans (in 256 patients) showed increased FDG uptake (244 scans in NHL and 110 in HD): in 286 cases, FDG uptake was considered pathological and indicative of ML, in 41 cases the findings were described as uncertain or equivocal and in 37 cases, FDG uptake was considered unrelated to ML (in ten scans, concurrent findings of abnormal FDG uptake attributed to ML and uptake assigned to other causes were obtained) . Of the 286 patients with positive PET findings, 274 (95.8%) were found to have residual or recurrent ML (i.e. true positives). Four of the 41 patients with inconclusive findings turned out to have ML, while in 13 patients, pathological processes other than ML could be identified as the cause of FDG uptake. ML was excluded in all patients with findings reported as non-pathological (100% true-negative rate). Therefore, the false-positive rate in our series was about 5%. The main cause of increased FDG uptake mimicking ML was inflammation. CONCLUSION: Our data confirm that 18F-FDG-PET has very high but not absolute specificity for ML. As already suggested, increased FDG uptake may also be observed in patients without active disease; in most cases, however, non-pathological FDG accumulation is properly identified. Less frequently, inconclusive scans are encountered; these cases are usually caused by inflammation, which subsequently resolves.

Adolescent↗
PubMed2005

Potential pitfalls of 18F-FDG PET in a large series of patients treated for malignant lymphoma: prevalence and scan interpretation.

OBJECTIVE: To evaluate the prevalence and scan interpretation criteria useful in identifying non-tumoural F-FDG focal uptakes (potential pitfalls) in patients who had been previously treated for a malignant lymphoma studied by positron emission tomography (PET). MATERIALS: Nine hundred and ninety-six consecutive PET scans obtained in 706 patients with malignant lymphoma were reviewed. All patients had been previously treated by first-line chemo-radiotherapy, plus surgery when required, and were then studied by FDG PET to investigate suspected recurrence at doubtful or inconclusive conventional radiological imaging (ultrasound, computed tomography, magnetic resonance imaging). PET was obtained with patients in the fasted condition and after i.v. injection of 370 MBq of F-FDG; imaging was acquired 60-90 min later. In patients with focal FDG uptake the final diagnosis was reached on the basis of histological findings or long-term follow-up. RESULTS: Thirty-one of 134 PET scans (23.1%) showing focal FDG uptake were diagnosed as non-tumoural radiotracer uptake, related to the presence of brown fat in seven cases, thymic hyperplasia in five, muscles contraction in four, lymph node unspecific inflammation in four, mediastinal/pulmonary unspecific inflammation in four, gastritis in two, colitis in two, bacterial abscess in one, lactating breast in one, and herpes zoster in one. Each of the above cited situations has been reported in the literature, generally in the form of sporadic reports, as a potential cause of misinterpretation (false positive) in reading a PET scan with the potential for incorrect patient management. An accurate diagnosis in these patients was important for the following therapeutic decision making. CONCLUSIONS: In the whole series of patients with treated malignant lymphoma, the prevalence of non-tumoural FDG focal uptake during follow-up was relatively low (3.1%); conversely, it was relatively high when considering the sub-group of 'positive' PET only (23.1%). The importance of knowing these situations in order to avoid misinterpretation in reading PET scans needs to be emphasized. In this light, an accurate patient's history and a skilful nuclear medicine physician are very important factors. For the same purpose, it is reasonable to think that the use of hybrid PET/CT tomographs could also play an important role in helping to identify non-tumoural FDG focal uptake.

Artifacts↗