68Ga-DOTATOC PET/MR imaging and radiomic parameters in predicting histopathological prognostic factors in patients with pancreatic neuroendocrine well-differentiated tumours.

PURPOSE: To explore the role of fully hybrid 68Ga-DOTATOC PET/MR imaging and radiomic parameters in predicting histopathological prognostic factors in patients with pancreatic neuroendocrine tumours (PanNETs) undergoing surgery. METHODS: One hundred eighty-seven consecutive 68Ga-DOTATOC PET/MRI scans (March 2018-June 2020) performed for gastroenteropancreatic neuroendocrine tumour were retrospectively evaluated; 16/187 patients met the eligibility criteria (68Ga-DOTATOC PET/MRI for preoperative staging of PanNET and availability of histological data). PET/MR scans were qualitatively and quantitatively interpreted, and the following imaging parameters were derived: PET-derived SUVmax, SUVmean, somatostatin receptor density (SRD), total lesion somatostatin receptor density (TLSRD), and MRI-derived apparent diffusion coefficient (ADC), arterial and late enhancement, necrosis, cystic degeneration, and maximum diameter. Additionally, first-, second-, and higher-order radiomic parameters were extracted from both PET and MRI scans. Correlations with several PanNETs' histopathological prognostic factors were evaluated using Spearman's coefficient, while the area under the curve (AUC) of the receiver operating characteristic (ROC) curve was used to evaluate parameters' predictive performance. RESULTS: Primary tumour was detected in all 16 patients (15/16 by 68Ga-DOTATOC PET and 16/16 by MRI). SUVmax and SUVmean resulted good predictors of lymphnodal (LN) involvement (AUC of 0.850 and 0.783, respectively). Second-order radiomic parameters GrayLevelVariance and HighGrayLevelZoneEmphasis extracted from T2 MRI demonstrated significant correlations with LN involvement (adjusted p = 0.009), also showing good predictive performance (AUC = 0.992). CONCLUSION: This study demonstrates the role of the fully hybrid PET/MRI tool for the synergic function of imaging parameters extracted by the two modalities and highlights the potentiality of imaging and radiomic parameters in assessing histopathological features of PanNET aggressiveness.

FDG PET-derived parameters as prognostic tool in progressive malignant pleural mesothelioma treated patients.

PURPOSE: The value of FDG PET-derived parameters in predicting overall survival (OS), local relapse-free survival (LRFS) and distant relapse-free survival (DRFS) in treated patients with malignant pleural mesothelioma (MPM) was evaluated. METHODS: This retrospective evaluation included 55 MPM patients treated between March 2006 and February 2015 with FDG PET/CT-guided salvage helical tomotherapy (HTT) after previous surgery plus chemotherapy. Univariate Cox regression analysis was performed to assess the impact of the following FDG PET-derived parameters: biological target volume (BTV), mean and maximum standardized uptake values (SUVmean/max), metabolic tumour volume (MTV) and total lesion glycolysis (TLG), measured using different uptake thresholds (40%, 50% and 60%). Logistic regression was then performed to identify the best FDG PET-derived parameters for selecting patients with poorer survival. RESULTS: The median OS was 9.1 months (range 0.0 - 69.6 months) after the end of HTT; 54/55 patients were dead at the last follow-up. BTV and TLG40, TLG50 and TLG60 were the most significant predictors of OS (p < 0.005). The median OS was 4.8 months in patients with MTV60 >5 cm3 and TLG40 >334.4, compared with 13.8 months and 16.1 months in patients with smaller values, respectively. The median LRFS and DRFS were 6.2 months (range 1.2 - 39.4 months) and 6.5 months (0.0 - 66.4 months), respectively. TLG40, TLG50 and TLG60 were significantly correlated with LRFS (p < 0.015). Median DRFS was 6.4 months in patients with MTV40 >39.6 cm3 and 6.2 months in patients with TLG40 >334.4, compared with 17 months and 18.8 months in patients with smaller values. BTV, TLG40 and MTV40 were also found to be good predictors in patients with poor OS/LRFS/DRFS (median survival times less than the median values). CONCLUSION: FDG PET-derived parameters effectively discriminated patients with a poor prognosis and may be helpful in the selection of MPM patients for salvage HTT.

Unusual presentation of sarcoid-like reaction on bone marrow level associated with mediastinal lymphadenopathy on (18)F-FDG-PET/CT resembling an early recurrence of Hodgkin's Lymphoma.

(18)F-FDG-PET/CT is widely employed to evaluate lymphoma patients. False positive results are quite frequent, generally due to active phase of inflammation. We describe an unusual PET/CT presentation of a sarcoid-like reaction (SLR) in a patient monitored for Hodgkin Lymphoma characterized by an intense uptake in lymph nodes and multiple bone foci in a PET/CT study. The final diagnosis was obtained by biopsy. This study draws attention to the fact that multifocal bone marrow uptakes due to a sarcoideal reaction may be a possible cause of false positive results in (18)F-FDG-PET/CT studies in oncology patients.

Presentación inusual de reacción sarcoidea en médula ósea asociada a adenopatía mediastínica en estudio PET-TAC con 18F-FDG simulando recidiva precoz de Linfoma de Hodgkin / Unusual presentation of sarcoid-like reaction on bone marrow level associated with mediastinal lymphadenopathy on 18F-FDG-PET/CT resembling an early recurrence of Hodgkin's Lymphoma

La PET-TAC con 18F-FDG se usa habitualmente en la evaluación de pacientes con linfoma. Son frecuentes los falsos positivos, generalmente debidos a inflamación en fase activa. Describimos una presentación inusual de una reacción sarcoidea, caracterizada por una captación intensa en ganglios y en múltiples huesos, en un estudio PET en paciente en seguimiento por linfoma de Hodgkin. El diagnóstico final se obtuvo mediante biopsia. Este trabajo hace notar que captaciones múltiples óseas debidas a reacción sarcoidea pueden ser una posible causa de resultado falso positivo en estudios PET en pacientes oncológicos(AU)

18F-FDG-PET/CT is widely employed to evaluate lymphoma patients. False positive results are quite frequent, generally due to active phase of inflammation. We describe an unusual PET/CT presentation of a sarcoid-like reaction (SLR) in a patient monitored for Hodgkin Lymphoma characterized by an intense uptake in lymph nodes and multiple bone foci in a PET/CT study. The final diagnosis was obtained by biopsy. This study draws attention to the fact that multifocal bone marrow uptakes due to a sarcoideal reaction may be a possible cause of false positive results in 18F-FDG-PET/CT studies in oncology patients(AU)

Clinical role of positron emission tomography (PET) in endocrine tumours.

Positron emission tomography (PET) is considered one of the most effective nuclear medicine imaging modality in oncology. In many types of malignant tumours PET has proven to be high sensitive in detecting both primary neoplasm and metastatic disease both before therapy for staging purposes and after surgery, radiotherapy and chemotherapy during follow-up. In particular, PET showed high accuracy in differentiating post-treatment scar from viable tumoural tissue and high sensitivity in visualising very small metastatic foci as those in normal-sized (less than 1 cm in diameter) lymph nodes. A large variety of positron emitter tracers have been produced for PET imaging: the most widely used tracer in clinical oncology is 18F-fluoro-2-deoxy-D-glucose (18F-FDG). Deoxy-glucose (DG) is a glucose analog that enters the cell using specific transmenbrane carrier proteins (especially GLUT-1). Once within the cytoplasm, DG is phosphorylated to FG-6-phosphate but does not appear to be further metabolised. In most malignant tumours there is an increase of the glycolityc metabolism which accounts for an increase of the FDG uptake. However, the metabolic cellular activity can be only slightly increased or even normal in well differentiated and slow growing tumours as some endocrine neoplasms. In the present review, the clinical usefulness and limits of PET imaging are discussed in the management of patients with endocrine tumors.

[Use of SPECT with (99m)Tc-Sestamibi in a patient affected by laryngeal carcinoma and parathyroid adenoma]. / Uso del SPECT con (99m)Tc-Sestamibi en un paciente afecto de un carcinoma laríngeo y de un adenoma paratiroideo.

We report the case of a patient with a laryngeal carcinoma in whom asymptomatic hyperparathyroidism was also detected during the preoperative work-up. A planar (201)Thallium/(99m)Tc-pertecnetate subtraction scintigraphy was performed in order to locate the suspected parathyroid adenoma. The study showed a single area of increased (201)Thallium uptake just above the thyroid isthmus, likely due to the laryngeal tumor. The scintigraphic study was repeated using (99m)Tc-Sestamibi and (99m)Tc-pertechnetate and employing the SPECT technique. Both SPECT studies made it possible to identify correctly the parathyroid adenoma, located inferiorly and in a posterior position to the lower third of the right thyroid lobe. The laryngeal tumor and parathyroid adenoma could be excised in a single surgery session. This case is of interest due to the rarity of the coexistence of two neck tumors and the clear advantage shown by the SPECT technique with (99m)Tc-Sestamibi over the planar technique with 201Thallium.

Uso del spect con 99m tc-sestamibi en un paciente afecto de un carcinoma laríngeo y de un adenoma paratiroideo / Use of SPECT with 99m Tc-SESTAMIBI in a patient affected by laryngeal carcinoma and parathyroid adenoma

Presentamos el caso de un paciente afecto de neoplasia laríngea en el cual se encontró hiperparatiroidismo asintomático en la evaluación preoperatoria. Se efectuó una gammagrafía de sustracción con 201Talio y 99mTc-pertecnetato para la localización preoperatoria del adenoma paratiroideo que se sospechaba, que evidenció una única área de captación anómala, referible al tumor laríngeo.El examen fue repetido con 99mTc-sestamibi y con 99mTc-pertecnetato utilizando la técnica de imagen tomográfica (SPECT), en vez de la planar. Los dos SPECT (con 99mTc-sestamibi y con 99mTc-pertecnetato) permitieron además individualizar correctamente el adenoma paratiroideo, situado inferiormente y en localización posterior respecto al lóbulo tiroideo derecho. La intervención quirúrgica permitió la extirpación en un tiempo, de la neoplasia laríngea y del adenoma paratiroideo. El interés del caso deriva, no solo de la rareza de encontrar la coexistencia de dos neoplasias diferentes en el mismo paciente, sino también por la evidente ventaja proporcionada por la técnica SPECT con 99mTc-sestamibi respecto a la planar con 201Talio (AU)

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