The quarterly journal of nuclear medicine and molecular imaging : official publication of the Italian Association of Nuclear Medicine (AIMN) [and] the International Association of Radiopharmacology (IAR), [and] Section of the Society of...最新文献

Background: To evaluate the power of volumetric and radiomic tissue data obtained from the images of the lesions in predicting the histopathological diagnosis in patients with incidental colorectal focal FDG uptake detected by [¹⁸F]FDG PET/CT imaging.

Methods: Electronic records of patients who underwent [¹⁸F]FDG PET/CT for various malignancies between January 2016 and January 2020 were retrospectively reviewed. 98 lesions of 80 patients with colonoscopic and histopathological results were included in the study. The lesions were divided into 3 groups according to their histopathological diagnosis as benign, premalign and malign. [¹⁸F]FDG PET/CT images obtained from the patients were evaluated using LIFEx software. Volumetric and radiomic textural features were obtained by establishing the region of interest (ROI) of the primary tumor. The [¹⁸F]FDG PET/CT parameters of the lesions were compared between the groups. In order to evaluate the predictive power of the parameters obtained with [¹⁸F]FDG PET/CT, the area under the curve (AUC), sensitivity and selectivity values, negative and positive predictive values were calculated by ROC analysis.

Results: The volumetric and radiomic tissue analysis parameters of the lesions in the malignant group were significantly different when compared to the other groups. Our study showed that SUVmax value can be used as a marker in the diagnosis of pathological malignancy (AUC=0.737 and P=0.001 95% CI: 0.619-0.855). Contrast and entropy parameters of GLCM matrix, which are radiomic texture features, were found to be used in the prediction of malignancy (AUC=0.685 and AUC=0.692, P=0.041 and P=0.035, respectively. Similarly, parameters of NLGDM, GLRLM and GLZLM matrices were shown to have statistically significant diagnostic values in predicting malignancy. However, no superiority of these parameters over each other in predicting malignancy was observed.

Conclusions: In our study, the parameters of radiomic textural analysis together with volumetric parameters have been shown to have diagnostic value in noninvasively determining lesion characterization and defining tissue in lesions with incidental colorectal focal FDG uptake detected by [¹⁸F]FDG PET/CT imaging.

Background: Aim of the present study was to evaluate the clinical impact of fluorine-¹⁸F-fluorodeoxyglucose PET/CT (¹⁸F-FDG-PET/CT) concurrent with post-therapeutic whole-body radioiodine scan (TxWBS) after first radioiodine (RAI) treatment in patients with high-risk differentiated thyroid carcinoma (DTC).

Methods: This was a retrospective, single-center study including 39 patients with DTC (22 females, 17 males, median age 54; IQR: 35-60 years, 87% papillary thyroid cancer, 13% follicular thyroid cancer). All patients underwent ¹⁸F-FDG-PET/CT and RAI treatment, both performed off L-T4 about 3 months after total thyroidectomy. TxWBS was obtained 3 days afterwards using planar technique and SPECT/CT of neck and thorax regions. Semiquantitative analysis was performed on positive ¹⁸F-FDG-PET/CT scans to assess SUVmax, SUVratio, MTV and TLG values in target lesions (hottest ¹⁸F-FDG-positive lesion present in each patient). Receiver operating characteristics (ROC) curve analysis was obtained to establish a cut-off point for SUVmax able to predict the presence of RAI nonavid lesions. Univariate and multivariate analyses were executed to find out predictive factors for abnormal ¹⁸F-FDG-PET/CT imaging.

Results: In 11 (28%) patients 18F-FDG-PET/CT and TxWBS were both negative and in 9 (23%) both positive, showing loco-regional or distant metastases. In 14 patients (36%) ¹⁸F-FDG-PET/CT showed more lesions than TxWBS, while in 5 (13%) patients more lesions were present at TxWBS than 18F-FDG-PET/CT. Overall, 23 patients (59%) showed ¹⁸F-FDG avid lesions and ¹⁸F-FDG-PET/TC changed the management in 14 (36%), including the choice to perform RAI therapy with higher activities than expected, lymph-node dissection for loco-regional metastases, direct therapy for solitary bone metastases. Through ROC curve analysis, a value superior to 7.25 of SUVmax was able to predict the presence of RAI non-avid lesion at TxWBS. Serum stimulated thyroglobulin and extranodal invasion resulted to be risk factors for abnormal ¹⁸F-FDG-PET/CT imaging. However, only extranodal invasion turned out to be an independent risk factor for abnormal ¹⁸F-FDG-PET/CT.

Conclusions: The present study demonstrated the clinical value of RAI-concurrent ¹⁸F-FDG-PET/CT in patients with high-risk DTC. However, some questions remain open, including the pretherapeutic thyroglobulin level to use as indication to ¹⁸F-FDG-PET/CT and the predictive value of ¹⁸F-FDG-PET/CT semiquantitative parameters.

Bone involvement in primary hyperparathyroidism (PHPT) is characterized by reduced bone mineral density (BMD) using dual X-ray absorptiometry (DXA). A hallmark of PHPT is BMD loss at cortical sites while trabecular bone remains relatively preserved. PHPT is associated with increased fracture risk at both trabecular and cortical skeletal sites, which cannot be explained based on BMD values alone. The application of the trabecular bone score (TBS), an index of the lumbar spine DXA bone microarchitecture, showed lower TBS values and increased risk of fractures in PHPT patients, independent of BMD. Although further prospective studies are needed, promising data have been published with the use of TBS and some advanced DXA-based imaging modalities in patients with PHPT.

Primary hyperparathyroidism is a hard-to-diagnose condition that can run without symptoms for many years without causing symptoms; yet, it can cause dire long-term consequences, such as osteoporosis and renal impairment. First-line diagnostic methods include ultrasound and parathyroid scintigraphy, which provide unsatisfactory results in terms of detection rate. Second-line imaging methods include [¹⁸F]F-Choline PET/CT, 4D-CT, and their combination. These methods have shown a great detection rate and sensitivity; however, they are to this day less widespread than the first-line ones. Both the two methods (PET and 4D-CT) have their specific advantages and field of application, as well as their specific limitations. In this narrative review, we will describe the advantages and disadvantages of the two techniques extensively. Moreover, we will try to identify whether the combined examination can play a role and how relevant this role is. Finally, we will try to define the specific clinical situation in which each method can provide the best contribution to diagnosing parathyroid tissue hyperfunction.

Background: The BRAF V600E mutation (BRAF mut) in papillary thyroid cancer (PTC) has been associated with poor response to therapy with ¹³¹I in patients with metastases but the results in postsurgical treatment are controversial. Our main objective is to investigate the impact of the mutation on the biokinetics of the administered ¹³¹I therapy after surgery.

Methods: A prospective study was designed, from July 2015 to January 2018 which included patients with PTC receiving ¹³¹I therapy after surgical treatment. To study the biokinetics of the radioiodine in postoperative thyroid remnants, SPECT-CT images were acquired so as to obtain the following variables: percentage of remnant uptake at 2 and 7 days post-administration, effective half-life and time-integrated activity coefficient. All of them were compared depending on the mutational diagnosis and other clinical features and pathological variables.

Results: Sixty-one patients, and in total 103 thyroid remnants, were included. About 59% of patients were BRAF mutated. The mutation was associated with classic variant (88.5% vs. 11.5%; P=0.0001), desmoplastic reaction (85.7% vs. 14.3%; P=0.002), smaller tumor size (1.5 vs. 2.1 cm; P=0.024), nodal disease (3.3 vs. 1; P=0.001) and advanced stages (76.9% vs. 23%; P=0.014). The BRAFmut group had a lower percentage of ¹³¹I uptake at 2 days (0.17% vs. 0.47%; P=0.001) and at 7 days (0.02% vs. 0.1%; P=0.013); and a lower time-integrated activity coefficient (0.05h vs. 0.17 h; P=0.002). In univariate analysis, in addition to the mutation, the histological variant was significant but only for time-integrated activity coefficient (P=0.04). In multivariate analysis, only mutation determined the 2-day uptake (P<0.001) and the time-integrated activity coefficient (P<0.001).

Conclusions: The BRAF V600E mutation is associated with lower ¹³¹I uptake in thyroid remnants. Furthermore, it is an independent factor that decreases the effect of post-surgical ¹³¹I therapy, and therefore, it could be used as a potential tool to optimize the treatment of PTC.

Background: Omission errors in medical imaging can lead to missed diagnosis and harm to patients. The subject has been studied in conventional imaging, but no data is available for functional imaging in general and for PET/CT in particular. In this work, we evaluated the frequency and characteristics of perceptual omission errors in the PET component of oncologic PET/CT imaging, and we analyzed the hazardous scenarios prone to such modality-specific errors.

Methods: Perceptual omission errors were collected in one tertiary center PET/CT clinic during routine PET/CT reporting over a 26-month period. The omissions were detected either in reporting follow-up PET/CT studies of the same patient or during multidisciplinary meetings.

Results: Significant omission errors were found in 1.2% of the 2100 reports included in the study. The most common omissions were bone metastases and focal colon uptake. We identified six PET-specific causative factors contributing to the occurrence of omissions, and we propose solutions to minimize their influence.

Conclusions: The data presented here can help to promote the awareness of interpreting physicians to body areas that require higher attention and to implement reading strategies for improving the accuracy of PET/CT interpretation.

The use of alpha emitting radiotherapeutics is increasing, with further growth expected due to a number of clinical trials currently running involving new alpha emitters. However, literature concerning radiation safety aspects of alpha emitting radionuclides is limited and most of the available literature concerns ²²³Ra. In general, the occupational exposure from alpha emitting radionuclides is expected to be low, as are doses to the public from external exposure. However, care must be taken to avoid skin contamination, inhalation, and ingestion. Not all alpha emitting radionuclides are identical, they often have very different associated decay chains and emissions. The decay chains and the manufacturing process should be carefully examined to identify any long-lived progeny or impurities. These may have an impact on the radiation safety processes required to limit occupational exposure and for waste management. Doses to the public must also be assessed, either arising directly from exposure to patients treated with radiotherapeutics, or via waste streams. Risk assessments should be in place when starting a new service covering all aspects of the preparation and administration, as well as any foreseeable incidents such as skin contamination or patient death, and the appropriate steps to take in these instances. It is imperative that with the increase in the use of alpha emitting radiotherapeutics more literature is published on radiation safety aspects, especially for new alpha emitting radiotherapeutics which often have very different characteristics than the currently established ones.

Background: F18-FET PET has an established diagnostic role in adult brain gliomas. In this study we analyzed image derived static and dynamic parameters with available conventional MRI, histological, clinical and follow-up data in assessment of pediatric brain tumor patients at different stages of the disease.

Methods: Forty-four pediatric patients with median age 7 years, diagnosed with brain tumors and underwent forty-seven 18F-FET PET scans either initially (20 scans) or post-therapy (27 scans) were enrolled. Standardized analysis of summed FET PET images early from 10-20 min and late from 30-40 min post-injection were used for static (mean and maximum tumor to brain ratio [TBR] and biological tumor volume [BTV]) parameters evaluation as well as the time activity curve [TAC].

Results: Nineteen out of 20 initially assessed patients had pathologically and/or clinico-radiologically proven neoplastic lesions and one patient had pathologically proven abscess. Receiver operator curve (ROC) marked early TBR max 2.95, early TBR mean 1.76, late TBR max 2.5 and late TBR mean 1.74 as discriminator points with diagnostic accuracy reaching 90% when TBR max was combined with dynamic parameters. Significant association was found between initial FET scans, early and late BTV and event free survival (EFS) (P value=0.042 and 0.005 respectively). In post-therapy assessment, the diagnostic accuracy of conventional MRI was 81.48% when used alone and 96.30% when combined with F18-FET PET scan findings. A cutoff point of 3.2 cm³ for late BTV, in post-therapy scans, was successfully marked as a predictor for therapy response (P value 0.042) and was significantly associated with EFS (P value 0.002). In FET-avid / MRI non-enhancing lesions, early TBR max was able to detect highly malignant processes (high-grade tumors in initial scans and residue/recurrence in post-therapy scans) with 80% sensitivity and 100% specificity when cutoff value of 2.25 was used (P value=0.024). In patients with FET-avid brainstem lesions, whether enhancing or non-enhancing in MRI scans, 81.8% were associated with high risk diagnoses and 68.2% of them were associated with poor therapy outcome. The degree of FET uptake matched tumor-grading, but did not show significant association with OS or EFS (P value>0.05).

Conclusions: F18-FET PET seems to be an evolving pediatric neuro-imaging technique with valuable diagnostic and prognostic information at initial and post-therapy evaluation.