Fatemeh Behnia

Newer PET application with an old tracer: role of 18F-NaF skeletal PET/CT in oncologic practice.

The skeleton is one of the most common sites for metastatic disease, particularly from breast and prostate cancer. Bone metastases are associated with considerable morbidity, and accurate imaging of the skeleton is important in determining the appropriate therapeutic plan. Sodium fluoride labeled with fluorine 18 (sodium fluoride F 18 [(18)F-NaF]) is a positron-emitting radiopharmaceutical first introduced several decades ago for skeletal imaging. (18)F-NaF was approved for clinical use as a positron emission tomographic (PET) agent by the U.S. Food and Drug Administration in 1972. The early use of this agent was limited, given the difficulties of imaging its high-energy photons on the available gamma cameras. For skeletal imaging, it was eventually replaced by technetium 99m ((99m)Tc)-labeled agents because of the technical limitations of (18)F-NaF. During the past several years, the widespread availability and implementation of hybrid PET and computed tomographic (CT) dual-modality systems (PET/CT) have encouraged a renewed interest in (18)F-NaF PET/CT for routine clinical use in bone imaging. Because current PET/CT systems offer high sensitivity and spatial resolution, the use of (18)F-NaF has been reevaluated for the detection of malignant and nonmalignant osseous disease. Growing evidence suggests that (18)F-NaF PET/CT provides increased sensitivity and specificity in the detection of bone metastases. Furthermore, the favorable pharmacokinetics of (18)F-NaF, combined with the superior imaging characteristics of PET/CT, supports the routine clinical use of (18)F-NaF PET/CT for oncologic imaging for skeletal metastases. In this article, a review of the indications, imaging appearances, and utility of (18)F-NaF PET/CT in the evaluation of skeletal disease is provided, with an emphasis on oncologic imaging.

SPECT/CT bone scintigraphy to evaluate low back pain in young athletes: common and uncommon etiologies

Low back pain of various etiologies is a common clinical presentation in young athletes. In this article, we discuss the utility of SPECT/CT bone scintigraphy for the evaluation of low back pain in young athletes. The spectrum of lower spine lesions caused by sports injuries and identifiable on bone scan is presented along with strategies to avoid unnecessary irradiation of young patients. Also covered are pitfalls in diagnosis due to referred-pain phenomenon and normal skeletal variants specific to this age group.

Primary Rosai-Dorfman disease of the bone in a patient with history of breast cancer: appearance on 99mTc-MDP scintigraphy, CT, and X-ray.

A 49-year-old woman with history of breast cancer presented with pain at the level of the left anterior proximal tibia. An x-ray of the tibia demonstrated a lytic cortical lesion that prompted a whole-body 99mTc-MDP bone scan. The bone scan revealed intense bone remodeling at the level of the tibial lytic lesion and in the cervical spine. CT demonstrated an expansile lesion eroding the vertebral bodies of C6 and C7 with a large soft tissue component. A biopsy of the cervical spine mass demonstrated features diagnostic of Rosai-Dorfman disease without evidence of neoplastic cells.

Potential value of FDG PET-CT in diagnosis and follow-up of TAFRO syndrome

Dear Editor, Beginning in 2010, Takai and other Japanese physicians described a group of patients with a common set of clinical features, including thrombocytopenia (T), ascites (A), myelofibrosis (F), renal dysfunction (R), and organomegaly (O), hence TAFRO [1]. The majority of initial case reports were reported from Japan [2–4]. More recently, TAFRO syndrome has been reported in non-Asian patients around the world. TAFRO syndrome is considered to describe a sub-type of idiopathic multicentric Castleman disease (iMCD) that shares common symptoms and laboratory abnormalities due to a cytokine storm [5]. Whereas human herpes virus-8 (HHV-8) drives the hypercytokinemia in a cohort of immunocompromised patients, the etiology of HHV-8-negative MCD is not known, hence idiopathic MCD (iMCD) [6]. Patients present with heterogeneous clinical features and often deadly multiple organ dysfunction. Lack of familiarity with the disease is a major challenge for clinicians often resulting in delay or lack of proper treatment leading to death [7]. Imaging modalities, such as 18F-Fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT), CT, and ultrasound, are commonly used as part of the work-up in these patients to reach a diagnosis; however, no specific imaging diagnostic criteria have been suggested. Herein, we present the first-reported Hispanic case and a Caucasian case of TAFRO syndrome with iMCD. Both cases received PET-CTas a part of their work-up and evaluation.We discuss findings and potential benefits of PET-CT over CT.

Biliary Leak in the Postsurgical Abdomen: A Primer to HIDA Scan Interpretation

Postsurgical bile leaks can be associated with significant morbidity and even mortality, if not identified and treated at an early phase. Hepatobiliary iminodiacetic acid (HIDA) scan is an important test for detection of bile leaks in the postoperative abdomen. However, the lack of anatomical details on planar images can make interpretation difficult, especially in the setting of altered postsurgical anatomy. Familiarity with the expected postoperative appearance on HIDA scan and correlation with SPECT/CT or other imaging modalities when available are very important. The purpose of this review is to describe the expected findings on HIDA scan after common major abdominal surgeries that involve a change in biliary tree anatomy, and illustrate how to identify biliary leaks and avoid interpretation pitfalls.

Deep Vein Thrombosis Presenting on Pulmonary Ventilation and Perfusion Scintigraphy.

A 52-year-old woman presenting with dyspnea was referred for a ventilation and perfusion scan (VQ). VQ images (with Tc-DTPA [diethylene triamine pentaacetic acid aerosol] and Tc-MAA [macroaggregated albumin]) initially appeared normal; however, count rates on perfusion images were similar to ventilation images, implying little Tc-MAA had reached the lungs. Spot images of the injected extremity demonstrated focal Tc-MAA accumulation worrisome for a venous thrombus, subsequently confirmed by Doppler ultrasound. Careful attention to relative radiotracer count rates on VQ scans is crucial to ensure diagnostic utility. In addition, abnormal low perfusion radiotracer counts may unveil other pathology with important clinical implications.

Subcutaneously obstructed ventriculoperitoneal shuntogram.

A 65-year-old man presented with headache, altered mental status, and somnolence. The patient had a ventriculoperitoneal (VP) shunt revised a month earlier. A CT of the head was performed, which demonstrated interval development of hydrocephalus compared with the prior examination done at the time of the shunt revision. Further evaluation of the VP shunt dynamics was obtained through a radionuclide shuntogram using 99mTcO4. The shuntogram demonstrated passage of the radiotracer down the VP shunt tubing. This case illustrates the utility of radionuclide shuntogram in demonstrating an unusual cause of hydrocephalus after VP shunt placement.

Spontaneous regression of a metastatic melanoma pulmonary deposit following biopsy

Spontaneous complete and partial regression of metastatic melanoma is poorly understood, and is a rare phenomenon with less than 80 cases reported since 1866. Several correlations have been noted such as systemic or local infections, operative trauma, hormonal influences, nutrition and immunologic factors. We present FDG PET and CT findings in a patient with multiple pulmonary metastases of melanoma, one of which underwent regression following biopsy. We suggest immune system modulation, triggered by biopsy, could have played a role, although the precise mechanism remains unknown.

PET/CT in the Diagnosis and Workup of Sarcoidosis: Focus on Atypical Manifestations

Sarcoidosis is a multisystem disease characterized by the formation of noncaseating granulomas. Lung and intrathoracic lymph nodes are classic sites of involvement; however, sarcoidosis can affect any site in the body. The clinical course is extremely variable, and the imaging features are diverse and dependent on the affected site, degree of inflammation, and treatment the patient receives. Atypical manifestations and imaging findings can make diagnosis and/or management challenging. In addition, assessment of treatment response can be difficult in the setting of chronic disease. Fluorine 18 fluorodeoxyglucose (FDG) PET/CT is sensitive for assessment of the inflammatory activity of sarcoidosis in any organ. Although FDG PET/CT is not included in the standard workup for sarcoidosis, there has been growing evidence that supports the value of this examination in guiding diagnosis and management. FDG PET/CT may be especially useful for assessing reversible granuloma, treatment response, disease extent, occult disease, and cardiac or osseous sarcoidosis, and determining the most suitable biopsy site. Capability to image the entire body during a single examination is advantageous in cases of systemic disease such as sarcoidosis. The authors review the use of FDG PET/CT, providing up-to-date evidence and describing various cases of sarcoidosis in which FDG PET/CT has an important role in diagnosis and/or management. They also discuss the usefulness of FDG PET/CT in cases of selective manifestations of sarcoidosis. ©RSNA, 2018.

Lacrimal gland uptake on F-18 florbetapir amyloid positron emission tomography scan

In 2012, the Food and Drug Administration (FDA) approved the use of F-18 florbetapir to estimate β-amyloid neuritic plaque density when indicated. A normal scan will show increased radiotracer uptake in the white matter. Mild uptake in salivary glands, skin, muscles, and bones is considered normal. Being a new and infrequently performed study, familiarity with normal biodistribution and variants is important. We hereby present 2 cases with F-18 florbetapir uptake in lacrimal glands. Patients had no symptoms or known systemic conditions to explain this uptake. We speculate that lacrimal gland uptake of F-18 florbetapir could represent a normal variant.