Comparison between N13NH3-PET and 99mTc-Tetrofosmin-CZT SPECT in the evaluation of absolute myocardial blood flow and flow reserve.

BACKGROUND: PET/CT is the standard for quantitative assessments of myocardial blood flow (MBF), but it requires short-lived-tracers, costly, and not widely available. SPECT with Cadmium Zinc Telluride (CZT) detectors allows dynamic acquisition and quantitation of MBF. The study aims were to compare MBF measurements by 99mTc-tetrofosmin-CZT to N13NH3 PET/CT after regadenoson-induced coronary hyperemia and to evaluate the effect of attenuation correction (AC). METHODS: 54 patients were evaluated at rest and during vasodilation by 99mTc-tetrofosmin-CZT and N13NH3 PET/CT within 2 weeks. MBF and MBF reserve (MFR) were measured by CZT with or without AC (NAC). RESULTS: The global rest MBF was 0.76 ± 0.19 mL/min/gr by PET and 0.76 ± 0.24 by AC-CZT (P = NS) and 1.14 ± 0.4 by NAC-CZT (P < 0.001 vs PET and AC-CZT). Stress MBF was higher when measured by PET than AC-CZT (1.87 ± 0.45 vs 1.62 ± 0.68 mL/min/gr, P < 0.0008), but lower than NAC-CZT (2.36 ± 1.1, P < 0.0003). The MBF reserve ratio (MFR) was higher by PET than AC-CZT (2.52 ± 0.56 vs 2.22 ± 1 (P < 0.009) and NAC-CZT (2.18 ± 1.0, P < 0.004). Linear regression was better between PET (MFR and stress MBF) and AC-CZT than between PET and NAC-CZT. ROC curve analysis showed the significant ability of AC-CZT to predict MFR < 2 and stress MBF < 1.7 (AUC = 0.75 and 0.82 respectively) and to differentiate between normal and CAD patients (AUC = 0.747 and 0.892 for MFR and stress MBF, respectively). CONCLUSIONS: Our data show a reasonable correlation between MBF and MFR measured by N13NH3-PET and 99mTc-Tetrofosmin-CZT SPECT. NAC-CZT overestimates MBF. AC is recommended when using CZT for measuring MBF.

18F-FDG PET/CT in primary brain lymphoma.

The actual role of 18F-FDG PET/CT in evaluating primary brain lymphoma is still an open issue. Brain lymphoma usually show elevated 18F-FDG uptake, often higher than other brain tumors or inflammatory processes, but the metabolic behavior of this lymphoma is not still understood. Our aim was to investigate the particular metabolic behavior of this lymphoma. Forty six patients (21 female, 25 male) with histologically-confirmed brain lymphoma who underwent 18F-FDG PET/CT from vertex to the mid-thigh for initial staging were retrospectively evaluated. The PET images were analyzed visually and semi-quantitatively by measuring the maximum standardized uptake value (SUVmax), lesion-to-liver SUVmax ratio, lesion-to-blood pool SUVmax ratio and the tumor to normal brain uptake ratio (T/N ratio) and compared with epidemiological (age, sex, HIV infection) and morphological (tumor size, MRI appearance) characteristics. Thirty-eight patients (83%) had positive 18F-FDG PET/CT (average SUVmax was 15.6 ± 9.2; lesion-to-liver SUVmax ratio 5.8 ± 2.8; lesion-to-blood pool SUVmax ratio 7.1 ± 3.8, T/N ratio 3.1 ± 1.7) at the corresponding brain lesion; the remaining 8 (17%) were not 18F-FDG avid. 18F-FDG avidity was significantly associated with morphological appearance and tumor size and not correlated with other features. 18F-FDG PET/CT detected extracranial disease in two cases (4%) with negative bone marrow biopsies and CT. In conclusion, brain lymphomas are 18F-FDG avid in 83% of cases showing high 18F-FDG uptake and 18F-FDG avidity is correlated with tumor size and morphological appearance of the lesion. PET/CT helped to recognize extracranial disease in two patients.

Comparison between the summed difference score and myocardial blood flow measured by 13N-ammonia.

BACKGROUND: Both the myocardial perfusion pattern and myocardial blood flow (MBF) are used to assess patients with suspected coronary artery disease (CAD). The aim of this study was to compare the perfusion pattern (using the summed difference score [SDS]) to MBF in a consecutive group of patients undergoing PET/CT with 13 N-ammonia (13NH3). METHODS: 47 consecutive patients, aged 65 ± 12 years (42 men) with known or suspected CAD, underwent vasodilator stress/rest PET/CT with 13NH3 for clinical indications. The SDS was determined by a commercially available software based on a 17-segment model. MBF was measured at rest and during hyperemia by dynamic acquisition and single-compartment model analysis. From the rest and stress MBF, the absolute difference (stress-rest) in myocardial blood flow defined as difference in myocardial blood flow (DMBF) was derived. RESULTS: There were no significant differences between patients with no ischemia (SDS ≤ 1) and those with ischemia (SDS > 1) in CFR (2.84 ± 0.73 vs 2.63 ± 0.89, P = NS) and DMBF (1.34 ± 0.45 vs 1.24 ± 0.53 mL·minute-1·g-1, P = NS). There were however significant regional differences (141 different vascular territories in 47 patients) between these two groups (CFR: 2.84 ± 0.95 vs 2.16 ± 0.57, P < .001 and DMBF: 1.39 ± 0.6 vs 0.87 ± 0.39, P < .0001). The correlation between regional CFR and regional DMBF with SDS was significant (y = 2.7145e-0.059x R = 0.358 and y = 1.2769e-0.119x R = 0.44) CONCLUSION: The SDS is the difference between two measurements (stress-rest) and it correlates better with regional DMBF, which is another measurement that reflects the difference between stress and rest. The correlation is better on regional than global basis.

18F-FDG PET/CT in gastric MALT lymphoma: a bicentric experience.

PURPOSE: The role of 18F-FDG-PET/CT in evaluating gastric MALT lymphoma is still controversial. In the literature the detection rate of 18F-FDG-PET/CT in patients with gastric MALT lymphoma is variable, and the reason for this heterogeneity is not still clear. Our aim was to investigate the particular metabolic behavior of these lymphoma. MATERIALS AND METHODS: Sixty-nine patients (26 female, 43 male) with histologically confirmed gastric MALT lymphoma who underwent a 18F-FDG-PET/CT for initial staging from two centers were included. The PET images were analyzed visually and semi-quantitatively by measuring the maximum standardized uptake value (SUVmax), lesion-to-liver SUVmax ratio, and lesion-to-blood pool SUVmax ratio and compared with Ann Arbor stage, epidemiological (age, sex), histological (presence of gastritis, ulcer, H. pylori infection, plasmacytic differentiation, Ki-67 index), and morphological (tumor size, superficial lesions or mass-forming) characteristics. RESULTS: Thirty-six patients (52 %) had positive PET/CT (average SUVmax was 9±6.7; lesion-to-liver SUVmax ratio 3.7±2.6, lesion-to-blood pool SUVmax ratio 4.8±3.3) at the corresponding gastric lesion; the remaining 33 were not 18F-FDG-avid. In the univariate analysis, 18F-FDG avidity was significantly associated with morphological features (mass forming p<0.001 and high maximum diameter p<0.001), Ann Arbor stage (p=0.010), and Ki67 index (p<0.001) and not correlated with age, sex, presence of gastritis, ulcer, Helicobacter pylori infection, and plasmacytic differentiation. In the multivariate analysis, the correlations with gross morphological appearance, Ann Arbor stage, and Ki-67 score were confirmed. SUVmax, lesion-to-liver SUVmax ratio, and lesion-to-blood pool SUVmax ratio correlated significantly only with Ki67 index (p=0.047; p=0.012; p=0.042). CONCLUSIONS: 18F-FDG avidity was noted in 52 % of gastric MALT lymphoma and this avidity is correlated with gross morphological characteristics, tumor stage, and Ki-67 index. SUVmax, lesion-to-liver SUVmax ratio, and lesion-to-blood pool SUVmax ratio are correlated only with Ki-67 index, and only lesion-to-liver SUVmax ratio was independently associated with Ki-67 score.

Differentiated Thyroid Cancer lymph-node relapse. Role of adjuvant radioactive iodine therapy after lymphadenectomy.

PURPOSE: Our purpose as to evaluate the impact of adjuvant radioactive iodine therapy (RAI) on prognosis, as assessed by progression-free survival (PFS) and overall survival (OS), in patients affected by differentiated thyroid carcinoma (DTC) lymph-node relapse and previously treated with lymphadenectomy. METHODS: We retrospectively evaluated DTC patients treated with lymph-node dissection for disease relapse. All patients had previously undergone total thyroidectomy and radioiodine remnant ablation (RRA). We used clinical and histological data obtained during follow-up to assess response and outcome. By means of univariate and multivariate time-to-event analyses, we assessed the impact of RAI on outcome (PFS and OS) and the prognostic role of thyroglobulin (Tg) levels under suppression with levothyroxine (Tg-on) measured 1-3 months after lymphadenectomy and of other risk factors. RESULTS: We evaluated 113 patients (age at diagnosis: median 41 years, interquartile range: 31-59), 64 of whom were treated with RAI. Over a median follow-up time of 5.7 years, 27 patients showed disease progression and 13 died. Kaplan-Meier PFS and OS curves showed that age on diagnosis, tumor histology, tumor size, DTC aggressive variant, and Tg-on were associated with prognosis. Patients with Tg-on ≥1 ng/ml treated with RAI showed a better PFS (Log-rank pp 0.001) and OS (p = 0.005) than untreated patients, while no effect of RAI was observed in patients with Tg-on <1 ng/ml. Multivariate models showed that age, Tg-on (≥1 vs. < 1 ng/ml, HR: 18.2, 95% CI: 5.09-64.8, p = 0.001) and RAI (Yes vs. No, HR: 0.36,95%CI: 0.15-0. 9, p = 0.02) remained the only independent factors associated with PFS, but only age and Tg-on remained significantly associated with OS (HR: 8.31, 95%CI:1.56-44.3, p = 0.01). Nonetheless, patients treated with RAI showed a lower risk of mortality (HR: 0.34, 95%CI: 0.1-1.15 p = 0.08) than untreated patients. CONCLUSIONS: RAI after lymphadenectomy for DTC relapse is significantly associated with better PFS only in patients with Tg-on ≥1 ng/ml.

1-23I-MIBG thyroid uptake: Implications for MIBG imaging of the heart.

BACKGROUND: 123I-MIBG has been widely used in patients with heart failure and neurological disorders. The patients are pre-treated with Lugol's oral solution or potassium perchlorate to prevent thyroid uptake of unlabeled 123I to limit the thyroid radiation exposure. However, despite the inhibition of the iodide pump, the thyroid is frequently visualized. The aim of this study was to study the pattern of thyroid uptake. METHODS: We reviewed the 123I-MIBG images of 57 patients studied in three different centers in Italy for cardiac (n = 42) or neurological (n = 15) indications. They were imaged at 15 minutes and 4 hours after injection and in all patients, the thyroid was included in the imaging field of view. In 2 of the 3 centers, the patients were pre-treated with Lugol's oral solution and/or potassium perchlorate (group 1) but in the third center, they were not (group 2). The following imaging parameters were evaluated: heart-to-mediastinum ratio (H/M), thyroid-to-mediastinum ratio (T/M) at 4 hours, and tracer wash out from the heart (HWO) and from the thyroid (TWO). RESULTS: In the cardiac patients, the HWO was 22.98 ± 7.16% and TWO was 11.4 ± 11.86% (P < .0001). The TWO was 12.2 ± 13.1% in group 1 and 10.05 ± 8.97% in group 2 (P = NS). In the neurological patients the HWO was 26 ± 8.1% and the TWO was 20.32 ± 6.41 (P < .05). The difference in TWO was statistically significant (P < .01) between cardiac and neurological patients, whereas the HWO was not. The 4-hour H/M was 1.49 ± 0.23 in cardiac patients vs 1.4 ± 0.39 in neurological patients (P = NS). The 4-hour T/M was 1.33 ± 0.3 in cardiac patients vs 1.15 ± 0.13 in neurological patients (P < 0.05). CONCLUSION: The thyroid visualization in MIBG imaging is likely an expression of thyroid sympathetic innervation. The differences in TWO and T/M ratio in cardiac and neurological patients probably express differences in thyroid dopaminergic receptors. Thus, pre-treatment with potassium perchlorate or Lugol's solution may not be justified in patients undergoing 123I-MIBG imaging in whom the risk of side effects due to pre-treatment could be higher than the risk due to thyroid radiation exposure.

18F-FDG PET/CT Demonstrating Crossed Cerebellar Diaschisis Due to Germ Cell Tumor of the Basal Ganglia: A Case Report.

ABSTRACT: Germ cell tumors of the basal ganglia are rare neoplasms that usually present with hemiparesis or other neurological symptoms. MR and PET/CT with different tracers have demonstrated their usefulness for the correct assessment of disease. Crossed cerebellar diaschisis refers to a depression in metabolism of a cerebellar hemisphere as a result of contralateral supratentorial lesions. We present a case in which MR and PET/CT were crucial for the assessment of left basal ganglia germ cell tumors with the presence of crossed cerebellar diaschisis.

Case Report: 18F-PSMA PET/CT Scan in Castration Resistant Prostate Cancer With Aggressive Neuroendocrine Differentiation.

The development of a neuroendocrine phenotype as a mechanism of resistance to hormonal treatment is observed in up to 20% of advanced prostate cancer patients. High grade neuroendocrine prostate cancer (NEPC) is associated to poor prognosis and the therapeutic armamentarium is restricted to platinum-based chemotherapy. Prostate-specific membrane antigen (PSMA)-based positron emission tomography (PET)/computed tomography (CT) imaging has recently emerged as a potential new standard for the staging of prostate cancer and PSMA-based radioligand therapy (RLT) as a therapeutic option in advanced metastatic castration resistant prostate cancer (mCRPC). PSMA-based theranostic is not currently applied in the staging and treatment of NEPC since PSMA expression on neuroendocrine differentiated cells was shown to be lost. In this case series, we present 3 consecutive mCRPC patients with histologically proven high grade neuroendocrine differentiation who underwent PSMA-PET/CT and surprisingly showed high tracer uptake. This observation stimulates further research on the use of PSMA-based theranostic in the management of NEPC.

68Ga-DOTATOC PET/CT and MR in the Evaluation of Meningeal Metastasis From Esthesioneuroblastoma: A Case Report.

ABSTRACT: Esthesioneuroblastoma is a rare malignant tumor arising from olfactory neuroepithelium. PET/CT with different tracers such as 18F-FDG and 68Ga-somatostatin-receptor tracers has demonstrated its utility for the evaluation of disease. We present the case of a woman previously treated for esthesioneuroblastoma performing MR and 18Ga-DOTATOC PET/CT demonstrating dural metastasis of disease with a strong correspondence between conventional and functional imaging.

Incidental Findings Suggestive of COVID-19 in Asymptomatic Patients Undergoing Nuclear Medicine Procedures in a High-Prevalence Region.

Infection with the novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) may remain asymptomatic, leading to under-recognition of the related disease, coronavirus disease, 2019 (COVID-19), and to incidental findings in nuclear imaging procedures performed for standard clinical indications. Here, we report about our local experience in a region with high COVID-19 prevalence and dynamically increasing infection rates. Methods: Within the 8-d period of March 16-24, 2020, hybrid imaging studies of asymptomatic patients who underwent 18F-FDG PET/CT or 131I SPECT/CT for standard oncologic indications at our institution in Brescia, Italy, were analyzed for findings suggestive of COVID-19. The presence, radiologic features, and metabolic activity of interstitial pneumonia were identified, correlated with the subsequent short-term clinical course, and described in a case series. Results: Six of 65 patients (9%) who underwent PET/CT for various malignancies showed unexpected signs of interstitial pneumonia on CT and elevated regional 18F-FDG avidity. Additionally, 1 of 12 patients who received radioiodine for differentiated thyroid carcinoma also showed interstitial pneumonia on SPECT/CT. Five of 7 patients had subsequent proof of COVID-19 by reverse-transcriptase polymerase chain reaction. The remaining 2 patients were not tested immediately but underwent quarantine and careful monitoring. Conclusion: Incidental findings suggestive of COVID-19 may not be infrequent in hybrid imaging of asymptomatic patients in regions with an expansive spread of SARS-CoV-2. Nuclear medicine services should prepare accordingly.

Prognostic role of pretreatment 18F-FDG PET/CT in primary brain lymphoma.

OBJECTIVE: Primary brain lymphoma is an aggressive extranodal non-Hodgkin lymphoma with poor prognosis. Many possible prognostic factors are investigated with controversial results, but possible prognostic role of 18fluorine-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) features remains unclear. Our aim was to study the metabolic behavior of brain lymphoma at 18F-FDG PET/CT and the prognostic impact of qualitative and semiquantitative PET/CT parameters. METHODS: Between 2006 and 2018, 52 patients (26 females and 26 males; mean age: 61 years) with histologically confirmed diagnosis of brain lymphoma who underwent 18F-FDG PET/CT for staging before any treatment were included. PET images were qualitatively and semiquantitatively analyzed by measuring the maximum standardized uptake value body weight (SUVbw), lean body mass (SUVlbm), body surface area (SUVbsa), metabolic tumor volume (MTV), and total lesion glycolysis (TLG). The Kaplan-Meier method was used to estimate the progression-free survival (PFS) and overall survival (OS) times. Cox regression models were performed to determinate the relation between qualitative and semiquantitative PET/CT features and OS and PFS. RESULTS: Thirty-nine patients had positive 18F-FDG PET/CT showing 18F-FDG uptake (mean SUVbw of 18.2; SUVlbm of 13.9; SUVbsa of 5; MTV of 14.8; TLG of 153) at the corresponding cerebral lesion; the remaining 13 were not 18F-FDG avid. Relapse or progression of disease occurred in 22 patients with an average time of 9.7 months; death occurred in 18 patients with an average of 7.9 months. There was no difference in PFS and OS between baseline PET/CT positive and negative groups or considering SUVbw, SUVlbm, and SUVbsa. PFS and OS was significantly shorter in patients with MTV ≥ 9.8 cm3 (p = 0.037 and p = 0.022, respectively) and TLG ≥ 94 (p = 0.045 and p = 0.0430, respectively). CONCLUSIONS: 18F-FDG avidity was noted in 75% of cases. Only metabolic tumor parameters (MTV and TLG) were independently correlated with PFS and OS.

Pulmonary mucosa-associated lymphoid tissue lymphoma: 18F-FDG PET/CT and CT findings in 28 patients.

OBJECTIVE: The aim of the study was to evaluate the CT and fluorine-18-fluorodeoxyglucose positron emission tomography/CT (18F-FDG PET/CT) imaging findings of lung mucosa associated lymphoid tissue (MALT) lymphoma. METHODS: 28 patients with histologically confirmed pulmonary MALT lymphoma who underwent a chest CT and 18F-FDG PET/CT for staging were retrospectively analysed. The CT images were evaluated to determine morphological pattern of appearance, laterality, localization, number, size, presence of thoracic lymphadenopaties and secondary/combined findings. PET images were analysed visually and semi-quantitatively by measuring the maximum standardized uptake value (SUVmax), lesion-to-liver SUVmax ratio and lesion-to-blood pool SUVmax ratio. The relationship between qualitative and semi-quantitative features at 18F-FDG PET/CT and CT findings were also analysed. RESULTS: A total of 57 pulmonary lesions were identified by CT: 37 areas of consolidation, 4 masses, 12 nodules and 4 ground-glass opacities. Solitary and multiple lesions were detected in 10 and 18 patients, respectively; among patients with multiple lesions, 16 were bilateral and 2 unilateral. 18F-FDG PET/CT revealed increased 18F-FDG uptake in 47/57 lesions, in 26/28 patients. 18F-FDG avidity was significantly associated only with tumour size. CONCLUSIONS: Pulmonary MALT lymphoma is 18F-FDG avid in most cases and 18F-FDG avidity is correlated with tumour size. Consolidation is the most frequent morphological pattern of disease presentation. Advances in knowledge: This study demonstrated that lung MALT lymphoma are 18F-FDG avid in most cases depending on tumour size. Single or multiple areas of consolidation are the most common pattern of presentation of lung MALT lymphoma at CT.

Hepatosplenic Candidiasis Detected by (18)F-FDG-PET/CT.

Hepatosplenic candidiasis is a fungal infection, which mostly affects patients with hematologic malignancies such as leukemia. The pathogenesis of this infection is not clear yet, and the liver is the most commonly affected organ. Diagnosis of hepatosplenic candidiasis can be only established via biopsy, since computed tomography (CT) scan, ultrasonography, and magnetic resonance imaging (MRI) yield non-specific results. The role of fluorine-18 fluorodeoxyglucose positron emission tomography /computed tomography ((18)F-FDG PET/CT) in diagnosis of hepatosplenic candidiasis remains undetermined, considering a few evidences in the literature. In this case report, we present the case of a 47-year-old patient, affected by acute myeloid leukemia, which was treated with three cycles of chemotherapy, resulting in the development of neutropenia and fever following the last cycle. The (18)F-FDG PET/CT scan showed some foci of intense FDG uptake in the liver and spleen. The subsequent diagnostic investigations (i.e., abdominal CT scan and biopsy) were suggestive of hepatosplenic candidiasis. The patient was started on antifungal treatment with fluconazole. After one month, the clinical conditions were resolved, and the subsequent abdominal CT scan was negative.

Diagnostic and Prognostic Value of 18F-FDG PET/CT in Male Breast Cancer: Results From a Bicentric Population.

PURPOSE: We aim to assess the diagnostic and prognostic values of 18Ffluorodeoxyglucose (FDG) positron emission tomography (PET)/computed tomography (CT) in a small population with male breast cancer (MBC). MATERIALS AND METHODS: From May 2005 to Jul 2013, we retrospectively reinterpreted 31 FDG PET/CT scans of 25 men (mean age: 67 years; range: 51-81 years) with a proven breast cancer diagnosis, from two Italian centers. In the majority of patients, an invasive ductal cancer was present (68%). PET/CT scan was performed for initial staging in 5 (16%), restaging in 18 (58%), restaging for the increase of tumor markers in 4 (13%), response to therapy in 2 (6%) and during follow-up in 2 cases (6%). The prognostic impact of PET/CT in this male breast cancer population was assessed by using Kaplan-Meier analysis. RESULTS: Nuclear medicine imaging was negative in 10 subjects while it resulted positive in the residual 15 patients (60%). At initial staging, in four out of five cases, PET/CT showed a significant uptake in the primary cancer and of those three had also a loco-regional lymphatic and distant metastatic involvement. In restaging setting, PET/CT was more accurate than conventional imaging for detection of distant metastases, resolving two false-positive findings. Finally, a positive PET/CT scan was demonstrated to be prognostically unfavorable as compared to a negative exam. CONCLUSIONS: MBC is a rare tumor with similar biological and metabolic characteristics of female breast cancer. FDG PET/CT seems to be useful, particularly in the restaging setting, to delineate the correct therapeutic approach and to predict the prognosis.

Incidental 18F-FDG PET/CT bilateral breast uptake due to carcinoma.

We report a case of 71-year-old female patient, previously treated with chemotherapy and surgical resection of sigmoid tract of the large bowel for adenocarcinoma (pT3N1M0), who underwent a 18F-FDG PET/CT for a suspicious hepatic lesion detected at CT scan during follow-up. 18F-FDG PET/CT showed no abnormal uptake in the liver both at 60 minutes and 120 minutes after injection but revealed a pathological uptake in two breast nodules, (one localized in upper-internal-quadrant of the right breast and the other in the upper-external-quadrant of the left breast). The patient underwent breast MRI, which confirmed the suspicious nature of both lesions; subsequently she underwent a trucut biopsy of both lesions witch demonstrated a bilateral localization of papillary carcinoma (both lesion were classified as pT1c). The patient underwent bilateral mastectomy and the final biopsy confirmed the presence of breast cancer, while bilateral sentinel nodes biopsy showed no lymph-nodes metastases.

Multicentric study on ¹8F-FDG-PET/CT breast incidental uptake in patients studied for non-breast malignant purposes.

AIM: Our study has aimed to establish the prevalence and pathological nature of fluorine-18-fluorodeoxyglucose ((18)F-FDG) breast incidental uptake (BIU) in patients studied for non-malignant breast tumours and then to compare our data obtained in three Italian nuclear medicine centres with those available in literature. MATERIAL AND METHODS: We retrospectively evaluated 42,927 (18)F-FDG-PET/CT scans performed on patients studied in three Italian Nuclear Medicine Centres. All patients underwent (18)F-FDG-PET/CT for oncologic purposes not related to breast disease. RESULTS: Among 42,927 scans, a BIU was identified in 79 (0.18%) patients, 75 (95%) female and 4 (5%) male with an average age of 62 ± 17 years. Twenty-five out of 35 (71.5%) BIUs were malignant and 10/35 (28.5%) benign. Among the 25/35 incidentalomas that were malignant, 12/25 (48%) were infiltrating ductal carcinoma, 5/25 (20%) ductal carcinoma (infiltrating and in situ), 4/25 (16%) lobular carcinoma, 2/25 (8%) ductal carcinoma in situ and 2/25 (8%) were metastases from the primary tumour under investigation. Of the 10 BIUs that were benign in the histological examination, after further investigations it was found that 9/10 (90%) were fibroadenomas and 1/10 (10%) was a benign lesion not better specified. The lesion to liver or to blood-pool SUVmax ratio in malignant lesions is significantly higher than in benign ones. CONCLUSIONS: Our multicenter study demonstrates that, although they are uncommon, BIUs show a high percentage of malignancy and therefore requires further research.

Multicentre study of 18F-FDG-PET/CT prostate incidental uptake.

AIM: The purpose of our study was to establish the prevalence and pathological nature of fluorine-18-fluorodeoxyglucose (18F-FDG) prostate incidental uptake (PIU) among patients studied for non-prostate-malignant purposes in three nuclear medicine centres. METHODS: We retrospectively evaluated 20,422 scans performed on male patients; all patients underwent 18F-FDG-PET/CT for purposes not related to prostate disease. RESULTS: Among 20,422 patients PIU was identified for 280 (1.4 %) with an average age of 70 ± 10.7 years. Sixty-three of the 280 patients with PIU (22.5 %) underwent PSA dosage and biopsy to determine the nature of the incidental uptake. Thirty-five of the 63 (55.5 %) PIU were malignant whereas 28/63 (44.5 %) were benign. The average value of PSA for patients with benign PIU was 3.7 ± 2.8 ng/ml whereas it was 7.8 ± 8.2 ng/ml in patients with malignant PIU; this difference was statistically significant. For malignant lesions, the average lesion-to-liver SUVmax ratio was 2.9 ± 2.5 and the average lesion-to-blood-pool SUVmax ratio was 3.7 ± 2.5. For benign lesions, the average lesion-to-liver SUVmax ratio was 2.5 ± 1.7 and the average lesion-to-blood-pool SUVmax ratio was 3.5 ± 2.4; there was no statistically significant difference between lesion-to-liver and lesion-to-blood-pool SUVmax ratios for benign and malignant lesions. CONCLUSION: Because PIU values are indicative of malignancy for a substantial percentage of patients, further investigation is required.

Incidental 11C-choline PET/CT uptake due to esophageal carcinoma in a patient studied for prostate cancer.

A 75-years-old patient with a history of prostate cancer, previously treated with radical prostatectomy, underwent C-choline PET/CT for restaging due to a rise in the prostate-specific antigen level. The study revealed a focal uptake of C-choline in the esophagus. A subsequent endoscopic examination showed the presence of an esophageal lesion, and after surgery, the histologic diagnosis was mildly differentiated squamous cell carcinoma. In our case, the incidental esophageal uptake revealed by C-choline PET/CT allowed the early diagnosis of an unsuspected esophageal carcinoma.