Faculty Bibliography

Objective/UNASSIGNED:Tumor-induced osteomalacia (TIO) is a rare osteomalacia characterized by paraneoplastic secretion of fibroblast growth factor 23. Concomitant occurrence of TIO during pregnancy is rarer still. Our objective was to report a young patient with debilitating fractures diagnosed with TIO who became pregnant and subsequently had her tumor localized by gallium-68 (Ga-68) DOTATATE positron emission tomography/magnetic resonance imaging (PET/MRI). Case Report/UNASSIGNED:A 28 year-old woman with a 2-year history of stress fractures was found to have the following: (1) alkaline phosphatase level, 220 (reference range, 30-95) U/L; (2) phosphorus level, 2.1 (2.5-5.0) mg/dL; (3) 1,25-dihydroxyvitamin D3 level, <8 (18-72) pg/mL; (4) 24-hour urine phosphorus level, 0.5 (0.3-1.3) g; and (5) fibroblast growth factor 23 levels, 1241 (reference range, <180) RU/mL. The patient became pregnant, and at term, a cesarean delivery was performed. Ga-68 DOTATATE PET/MRI showed a 9-mm intracortical mass in the right fibular head and right femoral and bilateral calcaneal stress fractures. The fibular lesion was resected; pathology showed a 1.5-cm lesion with positive fibroblast growth factor receptor 1 staining. Discussion/UNASSIGNED:This patient with TIO had an uneventful pregnancy and delivery. TIO is typically caused by benign mesenchymal tumors. Ga-68 DOTATATE PET/computed tomography has been used for localizing tumors causing TIO, yet MRI has superior contrast resolution over computed tomography. Therefore, it is not surprising that Ga-68 PET/MRI successfully localized this patient's tumor to the intracortical space of the fibular head and distinguished it from insufficiency fractures. Conclusion/UNASSIGNED:To our knowledge, this is the first report of phosphate treatment in a pregnant patient with TIO and the first report of a tumor-inducing TIO being localized by Ga-68 DOTATATE PET/MRI.

BACKGROUND AND PURPOSE:Accurate differentiation of paragangliomas and schwannomas in the jugular foramen has important clinical implications because treatment strategies may vary but differentiation is not always straightforward with conventional imaging. Our aim was to evaluate the accuracy of both qualitative and quantitative metrics derived from dynamic contrast-enhanced MR imaging using golden-angle radial sparse parallel MR imaging to differentiate paragangliomas and schwannomas in the jugular foramen. MATERIALS AND METHODS:test. A univariate logistic model was created with a binary output, paraganglioma or schwannoma, using a wash-in rate as a variable. Additionally, lesions were clustered on the basis of the wash-in rate and washout rate using a 3-nearest neighbors method. RESULTS:< .001). All 30 lesions were classified correctly by using a 3-nearest neighbors method. CONCLUSIONS:Paragangliomas at the jugular foramen can be reliably differentiated from schwannomas using golden-angle radial sparse parallel MR imaging-dynamic contrast-enhanced imaging when imaging characteristics cannot suffice.

Introduction: Molecular tests such as ThyroSeq are recommended in the workup of cytologically indeterminate thyroid nodules (ITN). While repeat molecular testing is often performed after repeat fine needle aspiration (FNA) yields persistently indeterminate cytology, ThyroSeq's inter-test reliability is unclear. We assessed consistency of initial and repeat ThyroSeq analyses performed on samples from the same thyroid nodules.
Method(s): All thyroid nodules diagnosed as ITN on consecutive FNAs that received ThyroSeq with both biopsies from 2014-2018 at our institution, were reviewed. Initial analysis was ThyroSeq v2 while repeat was v2 or v3. Nodules with gene mutations, fusions, or copy number alterations (CNA) were considered ThyroSeq-positive.
Result(s): During the study period, 30 patients underwent ThyroSeq analysis on initial and repeat FNA samples (median interval=21 months). On initial testing, 27 (90%) nodules were ThyroSeq-negative and 3 (10%) low-risk mutations (RAS, EIF1AX, TSHR) were identified. Repeat ThyroSeq re-identified these 3 nodules and also interpreted 9 initially ThyroSeq-negative nodules as positive (kappa=0.286). All 9 molecular alterations were low-risk, most were identified on v3 (7, 77.8%), and CNA was the most common change (6, 66.7%). Of 12 patients with ThyroSeq-positive nodules, 8 underwent lobectomy. Final pathology identified low-risk malignancy in 3 nodules; the remainder were benign.
Conclusion(s): New findings on repeat ThyroSeq are possible. Whether these findings were detected by expanded panel or are the result of de-novo changes is unknown. The risk of missing high-risk changes appears to be low. More studies are needed to characterize the concordance of ThyroSeq analyses and natural evolution of ITNs.
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Introduction: The prognostic significance of a singular RAS mutation in cytologically indeterminate thyroid nodules (ITN) is unclear. This study aimed to analyze the incidence of malignancy and clinical outcomes of ITNs diagnosed on fine needle aspiration (FNA) cytology with RAS mutations.
Method(s): All FNA ITNs that underwent ThyroSeq testing and thyroidectomy from 2014-2018 were reviewed. ITNs with RAS (N-, H-, or K-RAS) mutations identified on ThyroSeq testing were selected. Demographics, Bethesda classifications, genomic profiles, treatment, final pathology, and clinical outcomes were recorded.
Result(s): During the study period, 93 patients with cytologic diagnosis of ITN and RAS mutations were identified. The mean nodule size was 2.2 cm (range: 0.5-6.6 cm). Most nodules were classified as Bethesda III (77, 82.8%). NRAS mutations were the most common (53, 57%), followed by HRAS (24, 25.8%), and KRAS (16, 17.2%). The majority of patients were treated with thyroid lobectomy (67, 72%). On final pathology, 9 (10%) were diagnosed as malignant (follicular variant of papillary thyroid carcinoma [FVPTC]) and were distributed among all 3 RAS variants (NRAS: 4 [7.5%]; HRAS: 4 [16.7%]; KRAS: 1 [6.3%]; p=0.4). Most FVPTCs were encapsulated (8, 88.9%). With a median follow up of 19 months (interquartile range = 8-35), no recurrences or progression was seen.
Conclusion(s): The risk of malignancy in ITNs with singular RAS mutations is low. All malignancies were low-risk. Our findings demonstrate a low incidence of high-risk malignancy in ITNs with RAS mutations, suggesting that initial management with conservative approaches such as thyroid lobectomy may be justified.
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Most head and neck paragangliomas (PGLs) are biochemically silent and often present with recurrence and metastases in association with hereditary syndromes. Whole-body functional imaging is increasingly used to detect tumor extent and guide treatment planning of PGLs. [68Ga]-DOTATATE, which targets somatostatin receptor 2 (SSTR2) overexpression, has emerged as a sensitive functional imaging modality in PGLs. We present a patient with metastatic glomus caroticum PGL in whom [68Ga]-DOTATATE PET/MRI provided a more accurate characterization of metastatic extent, as compared to gadolinium-enhanced MRI of the neck and whole body [18F]-FDG PET/CT. We then review the current literature and discuss the imaging implications of [68Ga]-DOTATATE PET/MRI in PGLs.

Patients with renal cell carcinoma may develop metastases after radical nephrectomy, and therefore monitoring with imaging for recurrent or metastatic disease is critical. Imaging varies with specific suspected site of disease. Computed tomography/MRI of the abdomen and pelvis are mainstay modalities. Osseous and central nervous system imaging is reserved for symptomatic patients. Radiologic reporting is evolving to reflect effects of systemic therapy on lesion morphology. Nuclear medicine studies compliment routine imaging as newer agents are evaluated for more accurate tumor staging. Imaging research aims to fill gaps in treatment selection and monitoring of treatment response in metastatic renal cell carcinoma.