Nerve Root Metastasis of Breast Carcinoma Detected by Fluorodeoxyglucose Positron Emission Tomography/Computed Tomography Scan.

A 35-year-old woman with history of breast cancer was referred to our department for restaging by F-18 fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) scan. Aside from multiple other FDG-avid metastatic lesions, a segmental increased FDG uptake was visualized along the asymmetrically thicker left first sacral nerve root, highly concerning for metastatic disease, which was confirmed by the subsequently performed magnetic resonance imaging. Our case highlights the capability of FDG PET/CT scan in the correct diagnosis of the extremely rare phenomenon of nerve root metastasis as well as the importance of differentiating FDG-avid lumbosacral nerve roots from adjacent skeletal metastases.

Predictive and prognostic potential of pretreatment 68Ga-PSMA PET tumor heterogeneity index in patients with metastatic castration-resistant prostate cancer treated with 177Lu-PSMA.

Introduction: This study was conducted to evaluate the predictive values of volumetric parameters and radiomic features (RFs) extracted from pretreatment 68Ga-PSMA PET and baseline clinical parameters in response to 177Lu-PSMA therapy. Materials and methods: In this retrospective multicenter study, mCRPC patients undergoing 177Lu-PSMA therapy were enrolled. According to the outcome of therapy, the patients were classified into two groups including positive biochemical response (BCR) (≥ 50% reduction in the serum PSA value) and negative BCR (< 50%). Sixty-five RFs, eight volumetric parameters, and also seventeen clinical parameters were evaluated for the prediction of BCR. In addition, the impact of such parameters on overall survival (OS) was evaluated. Results: 33 prostate cancer patients with a median age of 69 years (range: 49-89) were enrolled. BCR was observed in 22 cases (66%), and 16 cases (48.5%) died during the follow-up time. The results of Spearman correlation test indicated a significant relationship between BCR and treatment cycle, administered dose, HISTO energy, GLCM entropy, and GLZLM LZLGE (p<0.05). In addition, according to the Mann-Whitney U test, age, cycle, dose, GLCM entropy, and GLZLM LZLGE were significantly different between BCR and non BCR patients (p<0.05). According to the ROC curve analysis for feature selection for prediction of BCR, GLCM entropy, age, treatment cycle, and administered dose showed acceptable results (p<0.05). According to SVM for assessing the best model for prediction of response to therapy, GLCM entropy alone showed the highest predictive performance in treatment planning. For the entire cohort, the Kaplan-Meier test revealed a median OS of 21 months (95% CI: 12.12-29.88). The median OS was estimated at 26 months (95% CI: 17.43-34.56) for BCR patients and 13 months (95% CI: 9.18-16.81) for non BCR patients. Among all variables included in the Kaplan Meier, the only response to therapy was statistically significant (p=0.01). Conclusion: This exploratory study showed that the heterogeneity parameter of pretreatment 68Ga-PSMA PET images might be a potential predictive value for response to 177Lu-PSMA therapy in mCRPC; however, further prospective studies need to be carried out to verify these findings.

68 Ga-FAPI-46 and 18 F-FDG in Advanced Metastatic Pancreatic Cancer.

ABSTRACT: Recently imaging with new PET radiotracers that act as fibroblast activation protein inhibitors (FAPIs) showed promising results in oncology and even nononcology imaging. Here we report a case of advanced pancreatic adenocarcinoma, imaged with both 18 F-FDG and 68 Ga-FAPI-46 PET/CT scans. The result indicated that imaging with 68 Ga-FAPI-46 showed significant improvement in detection of metastases as well as local malignancy recurrence. Moreover, the intensity and SUVs of the lesions were higher in 68 Ga-FAPI-46 scan compared with 18 F-FDG.

68Ga-PSMA PET/CT Scan Leading to Diagnosis of PSMA-Positive Rectal Adenocarcinoma in a Patient With Prostate Cancer.

ABSTRACT: A 59-year-old prostate cancer patient, status post radical prostatectomy, was referred to our department for restaging with 68Ga-prostate-specific membrane antigen (PSMA) PET/CT scan. Aside multiple metastatic lesions involving pelvic lymph nodes as well as the right femoral trochanter, a PSMA-positive rectal wall thickening was detected. Colonoscopy correlation and tissue diagnosis, recommended to rule out accompanying primary malignancy, confirmed the presence of rectal adenocarcinoma. This case signifies the importance of requesting pathological correlation for unexplained PSMA-positive lesions, emphasizing the potential role PSMA ligands may play in detecting occult second primary malignancies, especially synchronous/metachronous colorectal cancers.

177Lu-FAPI Therapy in a Patient With End-Stage Metastatic Pancreatic Adenocarcinoma.

ABSTRACT: A 52-year-old woman with metastatic pancreatic adenocarcinoma underwent imaging with 18F-FDG PET/CT and 68Ga-FAPI-46 PET/CT, which demonstrated malignancy recurrence in the surgical bed with multiple metastatic lesions, more extensive on 68Ga-FAPI-46 PET/CT. The patient was a candidate for therapy with 177Lu-FAPI-46 due to high uptake of lesions in 68Ga-FAPI-46 images and no other available therapeutic option. Posttreatment 177Lu-FAPI-46 scans showed rather rapid washout of the radiopharmaceutical from tumoral lesions. This case report suggests that, although 68Ga-FAPI-46 is a promising agent for tumor imaging, 177Lu-FAPI-46 may not be an optimal compound for theranostic applications.