Post-Topotecan Mixed Response and 'Redifferentiation-akin' Phenomenon on Dual Tracer PET-CT in Multiple Treatment-Resistant Metastatic Neuroendocrine Neoplasm.

A 50-year-old female patient of heavily pre-treated (chemotherapy and multiple treatment-resistant) and progressive intermediate-grade metastatic neuroendocrine neoplasm is presented, wherein the lesions showed mixed response following topotecan treatment and multiple hepatic metastasis showed increase in the SSTR expression and decrease in FDG concentration on dual-tracer PET/CT ( 68 Ga-DOTATATE and 18 F-FDG PET/CT). Such observation allowed 177 Lu-DOTATATE PRRT to be considered for an advanced, symptomatic, and multiple treatment-resistant patient with limited palliative treatment options left.

Tenosynovial Giant Cell Tumor of Foot in a Patient with Radioiodine-Refractory Thyroid Cancer: Imaging Findings on FDG-PET/CT, MRI, and Radioiodine Scan.

We herein illustrate a case of benign tenosynovial giant cell tumor, which was incidentally detected as FDG-avid lesion on PET/CT in a patient with radioiodine refractory thyroid cancer, with predominantly non-iodine concentrating disease. The lesion was followed up clinically and with local MRI annually for subsequent 3 years. The utility of hybrid PET-CT imaging, the non-iodine concentration of the tumor along with clinical knowledge, and findings on other imaging and pathological modalities in answering and diagnosing incidental benign musculoskeletal tumors in a patient with known thyroid malignancy are presented here.

Hurthle Cell Thyroid Carcinoma with Liver and Paraaortic Abdominal Nodal Metastasis: Progression on Sorafenib Therapy after Initial Disease Stabilization.

Hurthle cell thyroid carcinoma (HCTC) demonstrates inferior prognosis compared with other types of differentiated thyroid cancer (DTC), along with radioiodine refractoriness and relatively poor 131 I concentrating ability. We herein report a case of a middle-aged lady presenting with neck swelling for years, who on pre-surgery work-up was diagnosed to harbor metastatic nodal and lung lesions. Post-thyroidectomy and neck dissection, she was diagnosed with HCTC. Post-surgery, none of the lesions concentrated radioactive-iodine (RAI) sufficiently but showed FDG avid lesions as mediastinal nodes, lung nodules, solitary lytic sternal lesions, and unusual bilateral paraaortic abdominal nodes. She was put on tyrosine kinase inhibitor (sorafenib) and showed disease stabilization for the initial 3 years, but multiple toxicity symptoms while on sorafenib therapy that needed multiple dose adjustments. Over the period of the subsequent year, she developed significant disease progression with liver involvement. She was shifted to lenvatinib, which she tolerated well. The functional imaging profile with unusual metastatic sites, the aggressive clinical presentation and disease course of RAI refractory HCTC over 4 years on tyrosine kinase inhibitor therapy, and the role of molecular FDG-PET/CT imaging in disease monitoring and clinical management of such case is presented.

PET-Computed Tomography in Bone and Joint Infections.

This communication gives a short review of clinical utilities of PET/computed-tomography (CT) imaging in bone and joint infections. PET/CT imaging provides additional information over conventional modalities by providing information regarding disease extent in the bone as well as whole body, giving an idea of active pathology at the molecular level, and response evaluation. The roles of fluorodeoxyglucose have been examined in multiple indications, particularly in osteomyelitis, prosthetic joint infections, diabetic foot, and systemic diseases with skeletal involvement. The role of PET/CT imaging using other tracers like 18F-sodium fluoride, gallium-68 citrate, 18F-fluorodeoxyglucose-labeled WBCs, and futuristic PET/MR have been also discussed shortly.

Metachronous Adenocarcinoma of the Lung in the Setting of Metastatic Gastric Neuroendocrine Tumor: Value of Elucidating Discordance on Dual-Tracer PET/CT with Ki-67 Index.

Dual-tracer PET/CT (18F-FDG and 68Ga-DOTATATE) has become established practice in the management of metastatic neuroendocrine neoplasms (NENs) and has demonstrated the advantages to patient management of deciphering the molecular PET characteristics of the tumor. Judicious elucidation of the findings is important, especially in scenarios of discordance with reported histopathology, potentially leading to an unsuspected diagnosis such as second primary malignancies. Such a diagnosis established early in the disease course, and mostly at an asymptomatic stage, provides lead time for timely, appropriate management. This concept was elaborated in a case of incidentally detected 18F-FDG-avid metachronous lung adenocarcinoma in a patient with metastatic, well-differentiated gastric NEN, wherein dual-tracer PET/CT showed 18F-FDG-avid but not 68Ga-DOTATATE-avid lung opacity.

Estimation of Absorbed Doses of Indigenously Produced "Direct-route" Lutetium-177-[177Lu]Lu-DOTA-TATE PRRT in Normal Organs and Tumor Lesions in Patients of Metastatic Neuroendocrine Tumors: Comparison with No-Carrier-Added [177Lu]Lu-DOTA-TATE and the Trend with Multiple Cycles.

Background: Lutetium-177-labeled somatostatin analogue, [177Lu]Lu-DOTA-TATE is most commonly used across the world for peptide receptor radionuclide therapy (PRRT) of neuroendocrine tumors (NETs). The primary objective of this study was to estimate the absorbed doses in organs and tumor lesions in NET patients treated with indigenously produced "direct-route" [177Lu]Lu-labeled DOTA-TATE and impact of multiple treatment cycles on absorbed doses, and compare with those treated with no-carrier-added [177Lu]Lu-labeled DOTA-TATE. Materials and Methods: Sixty patients of NET were enrolled in this prospective study. These patients received up to 6 cycles of PRRT with [177Lu]Lu-DOTA-TATE (total 232 cycles) at 10- to 12-week intervals between the two successive therapy cycles. The patients were administered 5.55-7.4 GBq (150-200 mCi) of [177Lu]Lu-DOTA-TATE in 100 mL of normal saline over a period of 30 min. Postadministration whole-body planar scintigraphy were acquired at five time points 0.5 (prevoid), 2, 12, 24, and 72 h (postvoid) and one SPECT scan at 24 h (postvoid). Number of disintegrations was determined from time-activity curves generated by drawing regions of interests (ROIs) on the images. Tumor masses were derived from computed tomography (CT) data. The absorbed doses for normal organs and tumor lesions were calculated using OLINDA 2.1.1 software. The same were also estimated in a group of 22 patients who were treated with no-carrier-added [177Lu]Lu-labeled DOTA-TATE. Results: The mean absorbed organ doses (mean ± SD) in Gy/GBq received by normal organs were as follows: kidneys 0.64 ± 0.21, liver 0.10 ± 0.05, spleen 0.88 ± 0.35, bone marrow 0.04 ± 0.02, urinary bladder 0.26 ± 0.06, heart wall 0.04 ± 0.02, and whole-body 0.06 ± 0.02. Tumor dosimetry was performed in a total of 410 tumor lesions, the mean absorbed dose to the tumor lesions was 4.79 ± 4.23 Gy/GBq. Large variations were observed in absorbed doses received by these lesions (range: 0.15-21.26 Gy/GBq). With no-carrier-added [177Lu]Lu-DOTA-TATE, the mean absorbed organ doses (mean ± SD) in Gy/GBq received by normal organs were as follows: kidneys 0.76 ± 0.16, liver 0.10 ± 0.05, spleen 1.14 ± 0.31, bone marrow 0.05 ± 0.02, urinary bladder 0.27 ± 0.05, heart wall 0.06 ± 0.02, whole-body 0.07 ± 0.02, and tumor dose 5.87 ± 5.74. Conclusions: There was no statistically significant difference in the dosimetry data of patients treated with no-carrier-added (indirect route) [177Lu]Lu-labeled DOTA-TATE and the dosimetry data of patients treated with [177Lu]Lu-labeled with DOTA-TATE formulated using 177Lu produced through "Direct-route" and were comparable with the data reported.

Grade 3 metastatic neuroendocrine neoplasms of two unusual primary sites with contrasting differentiation characteristics: Dual tracer positron emission tomography and computed tomography imaging (18F-fluorodeoxyglucose and 68Ga-DOTATATE) correlates and their treatment implications.

The correlates of dual tracer positron emission tomography and computed tomography (PET-CT) (18F-fluorodeoxyglucose [18F-FDG] and 68Ga-DOTATATE) in patients of Grade 3 neuroendocrine neoplasms (NENs) are presented. The first, a patient of gall bladder NEN, operated, with histopathology suggestive of high-grade well-differentiated neuroendocrine tumors with MiB-1 labeling index of 35%, showed uptake with both 18F-FDG and 68Ga-DOTATATE, including an uptake equivalent to Krenning score of 3-4 on 68Ga-DOTATATE PET-CT; in the second, a patient of esophageal NEN, Grade 3 with poor differentiation features, with MiB-1 labeling index of 70%, thereby qualifying for Grade 3 neuroendocrine carcinoma, the FDG uptake was high with minimal uptake on 68Ga-DOTATATE PET-CT. The illustrations reiterate the impression that relative uptake of 68Ga-DOTATATE/FDG in the NEN lesions forms a valuable parameter for assessing the dynamic tumor biology in continuum and thus personalizing the treatment strategies.

18F-FDG PET/CT in a Rare Case of Poland Syndrome and Gastric Cancer.

ABSTRACT: Poland syndrome is a rare congenital anomaly characterized by unilateral aplasia of the sternoclavicular head of pectoralis major muscle with varying degree of same side upper limb anomalies. A 44-year-old man, with a case of adenocarcinoma of stomach, whose CECT chest revealed complete absence of pectoralis major and minor muscles on the left side, was diagnosed with Poland syndrome without presence of typical ipsilateral limb anomalies. Follow-up PET/CT revealed metabolically active recurrent disease with typical findings of Poland syndrome. It is important to be aware of oncologic association in a patient of Poland syndrome as highlighted in the present case.