Faculty Bibliography

BACKGROUND:There are no specific recommendations for FDG-PET/CT in assessing recurrent cutaneous squamous cell carcinoma (cSCC). OBJECTIVE:To evaluate FDG-PET/CT in recurrent cSCC. METHODS:FDG-PET/CT scans were retrospectively reviewed; sites of abnormal uptake were noted and correlated with biopsy/histopathology where available; follow-up imaging or clinical data in others. Comparison with available CT/MR was performed. Prognostic significance of PET/CT parameters was evaluated. PET/CT-based change in management was recorded. RESULTS:115 FDG-PET/CT scans were analyzed in 100 consecutive cSCC patients. Of these, 96 (84%) scans were positive for recurrence and 25 showed distant metastases. PET/CT detected unsuspected disease sites in 39/115 scans (34%): locoregional disease, 14; distant metastases, 11; both, 8; additional local cutaneous disease, 5; and second malignancy, 1. Comparison of 78 PET/CT scans with available CT/MR demonstrated 37 additional abnormalities on 23 PET/CT scans, predominantly including skin/subcutaneous lesions and nodes. PET/CT led to change in management in 28% of patients. On univariate/multivariate analysis, increased number of FDG-positive lesions and lung metastases on PET/CT were associated with increased risk of death/disease progression. LIMITATIONS/CONCLUSIONS:Retrospective study. CONCLUSIONS:FDG-PET/CT was sensitive in detecting recurrent disease in cSCC, led to change in management in 28% of patients, and proved to be of prognostic value.

BACKGROUND:The role of imaging in the management of Rosai-Dorfman disease (RDD), a rare non-Langerhans cell histiocytosis, is not clearly defined. We present an analysis of FDG PET/CT findings obtained for initial disease characterization, follow-up evaluation, and treatment planning for this disease. METHODS:From an institutional pathology database (2001-2018), we identified RDD patients who underwent FDG PET/CT scans either as part of clinical care or when done as part of clinical trials. For all scans, sites of abnormal FDG uptake were assessed, and SUVmax was measured. Comparison of PET/CT findings was made with anatomic (CT/MRI-based) imaging, where available. Instances of changing treatment based on PET/CT were recorded. RESULTS:We reviewed 109 FDG PET/CT scans in 27 patients with RDD. Five of 27 patients had only nodal/cutaneous disease, whereas 22 patients had extranodal disease, most commonly in bone (n = 9) and central nervous system (n = 7). PET/CT identified sites of active disease in 24 of 27 patients. All identified bone and extraskeletal lesions, except for a brain lesion in 1 patient, were FDG-avid. In 6 of 20 patients (30%) with available prior CT or MRI, PET/CT demonstrated additional RDD lesions (bones: n = 5, pleura: n = 1) that were not apparent on anatomic imaging; 3 of these lesions were outside the CT field of view, and 3 were not recognized on CT. Overall, 13 of 109 PET/CT scans led to a change in management, affecting 41% (11/27) of patients. CONCLUSION/CONCLUSIONS:FDG PET/CT was valuable in defining disease extent and optimizing treatment strategy in patients with RDD.

BACKGROUND:The chromium-51-labeled posttransfusion recovery (PTR) study has been the gold-standard test for assessing red blood cell (RBC) quality. Despite guiding RBC storage development for decades, it has several potential sources for error. METHODS:Four healthy adult volunteers each donated an autologous, leukoreduced RBC unit, aliquots were radiolabeled with technetium-99m after 1 and 6 weeks of storage, and then infused. Subjects were imaged by single-photon-emission computed tomography immediately and 4 hours after infusion. Additionally, from subjects described in a previously published study, adenosine triphosphate levels in transfusates infused into 52 healthy volunteers randomized to a single autologous, leukoreduced, RBC transfusion after 1, 2, 3, 4, 5, or 6 weeks of storage were correlated with PTR and laboratory parameters of hemolysis. RESULTS:Evidence from one subject imaged after infusion of technetium-99m-labeled RBCs suggests that, in some individuals, RBCs may be temporarily sequestered in the liver and spleen immediately following transfusion and then subsequently released back into circulation; this could be one source of error leading to PTR results that may not accurately predict the true quantity of RBCs cleared by intra- and/or extravascular hemolysis. Indeed, adenosine triphosphate levels in the transfusates correlated more robustly with measures of extravascular hemolysis in vivo (e.g., serum iron, indirect bilirubin, non-transferrin-bound iron) than with PTR results or measures of intravascular hemolysis (e.g., plasma free hemoglobin). CONCLUSIONS:Sources of measurement error are inherent in the chromium-51 PTR method. Transfusion of an entire unlabeled RBC unit, followed by quantifying extravascular hemolysis markers, may more accurately measure true posttransfusion RBC recovery.

BACKGROUND AND OBJECTIVES/OBJECTIVE:Histiocytoses are diverse hematopoietic diseases with disabling neurologic involvement. Recently, targeted mitogen-activated protein kinase pathway inhibitors have been used with clinical and radiologic response; however, some patients are unable to tolerate these treatments or have isolated and/or refractory neurologic, ocular, or head and neck (NOHN) disease. Intra-arterial administration of chemotherapy has conferred favorable responses in various neoplasms; however, treatment and outcomes across histiocytosis subtypes have not been examined. METHODS:Patients with biopsy-proven histiocytosis involving NOHN structures underwent an outpatient interventional procedure with angiography, selective catheterization, and intra-arterial infusion of melphalan, with target arteries depending on the site of disease. Patients were followed with radiologic (i.e., PET/CT, CT, MRI, or ophthalmic ultrasound and optical coherence tomography) and quantified functional assessments (i.e., vision, speech, or balance) as appropriate. Complete or partial radiologic and functional response rates were captured as well as frequency of subsequent progression. RESULTS:Eighteen patients underwent 74 total treatment instances. For 14 patients with radiologically evaluable tumorous disease, 10 (71%) had partial or complete response and the remaining 4 had stable disease; 3 of 14 (21%) had subsequent radiologic progression. Of 13 functionally evaluable patients, including 6 with neurodegenerative histiocytosis, 12 (92%) experienced functional improvement; 7 of 13 (54%) had subsequent functional worsening consistent with disease progression. There were no intraprocedural complications; 3 patients required hospitalization following treatment, including 1 patient with allergic reaction to melphalan. DISCUSSION/CONCLUSIONS:For patients with tumorous and neurodegenerative histiocytosis, intra-arterial melphalan represents a safe and highly effective treatment with potential to improve neurologic function. Additional study may clarify patients most suitable for this intervention. This novel treatment modality may represent a practice-changing innovation for refractory histiocytosis involving neurologic and ocular structures, as well as neurodegenerative forms. The treatment delivery form is novel, and future work should be directed at studying the efficacy of this modality to other forms of neurologic, ocular, head, and neck cancers. CLASSIFICATION OF EVIDENCE/METHODS:This study provides Class IV evidence that in patients with tumorous or neurodegenerative histiocytosis, selective angiographic catheterization and intra-arterial infusion of melphalan result in radiologic and functional improvement.

BACKGROUND/UNASSIGNED:I-PU-H71 is an imaging biomarker of epichaperome formation. The tracer has been established to localize in tissues under chronic stress, specifically in cancer cells and neurodegenerative brain cells. A first-in-human imaging trial using positron emission tomography (PET) in cancer patients revealed unexpected tracer accumulation in the myocardium. PURPOSE/UNASSIGNED:I-PU-H71 myocardial biodistribution and pharmacokinetics in a series of cancer patients with no history of cardiovascular disease. METHODS/UNASSIGNED:I-PU-H71 while at rest, followed by dynamic and gated/non-gated PET image data acquisitions. Region-of-interest (ROI) analysis of left ventricular myocardium (LVmyo) and background left atrium quantified tracer concentrations as standardized uptake value (SUV) and uptake ratios. Kinetic rate constants were evaluated by a two-tissue compartment model. RESULTS/UNASSIGNED:(IQR, 0.0015-0.0057). Regional assessment demonstrated essentially uniform tracer uptake in LV and myocardial segments; with normal LVEF in all patients (mean 57.7 ± 3.5%); and no patients suffered cardiac events over subsequent 12-month period. CONCLUSION/UNASSIGNED:I-PU-H71 PET. Our data indicates PU-H71 PET merits further study as a myocardial epichaperome biomarker, with potential application in drug development, possibly as a biomarker in subclinical cardiac dysfunction.

Somatostatin receptor imaging using 68Ga-DOTATATE PET is widely popular for evaluation of neuroendocrine tumors. 68Ga-DOTATATE PET/CT shows highest physiologic uptake in spleen followed by other organs such as kidneys, adrenal glands, and liver. Hemangiomas, although rare, are the most common primary benign neoplasm of the spleen, composed of endothelial-lined vascular channels. We present a case of 77-year-old man who underwent 68Ga-DOTATATE PET/CT scan for evaluation of pancreatic neuroendocrine tumor and incidentally demonstrated intense radiotracer uptake in splenic hemangiomata.