Incidental Skeletal Findings on Sodium-fluoride Positron Emission Tomography: A Collection of Benign Tumors

Sodium-fluoride (NaF) positron emission tomography (PET) is a sensitive method to detect altered bone mineralization. Its increasing use in routine clinical practice for metastatic bone disease has also resulted in the detection or characterization of incidental benign bone lesions. A spectrum of NaF PET scan cases with benign bone tumors are presented in this article, including whole body PET bone scan and selected PET/computed tomography (CT), CT, or magnetic resonance imaging (MRI) of the region of interest. The reader will be able to improve their knowledge related to the clinical presentation of these entities, some are rare and recognize based on NaF PET and CT/MRI patterns by reviewing these cases.

Nuclear Imaging of a Cardiac Paraganglioma.

We report a case of a cardiac paraganglioma in the right atrioventricular groove in which the use of different nuclear medicine studies aided in the diagnosis.

Vertebral Uptake of Tc-99m Macroaggregated Albumin (MAA) with SPECT/CT Occurring in Superior Vena Cava Obstruction.

A 67-year-old male presented with dyspnea for which lung scintigraphy was ordered to rule out pulmonary embolus. Planar images demonstrated abnormal midline uptake of Tc-99m macroaggregated albumin, which SPECT/CT localized to several thoracic vertebrae. Thoracic vertebral uptake on perfusion lung scintigraphy was previously described on planar imaging. Radionuclide venography and contrast-enhanced CT subsequently demonstrated superior vena cava (SVC) obstruction with collateralization through the azygous/hemiazygous system and vertebral venous plexus. SPECT/CT differentiated residual esophageal/tracheal ventilation activity, a clinically insignificant finding, from vertebral uptake indicative of SVC obstruction, a potentially life-threatening condition.

The dog prostate cancer (DPC-1) model: a reliable tool for molecular imaging of prostate tumors and metastases.

BACKGROUND: Clinical applicability of newly discovered reagents for molecular imaging is hampered by the lack of translational models. As the dog prostate cancer (DPC-1) model recapitulates in dogs the natural history of prostate cancer in man, we tested the feasibility of single-photon emission computed tomography (SPECT)/CT imaging in this model using an anti-prostate-specific membrane antigen (PSMA)/17G1 antibody as the radiotracer. METHODS: Immunoblots and immunohistochemistry (IHC) with 17G1 were performed on canine and human prostate cancer cell lines and tissues. Five dogs with DPC-1 tumors were enrolled for pelvic and, in some instances, thoracic SPECT/CT procedures, also repeated over time. Controls included (111)indium (In)-17G1 prior to DPC-1 implantation and (111)In-immunoglobulins (IgGs) prior to imaging with (111)In-17G1 in dogs bearing prostatic DPC-1 tumors. RESULTS: 17G1 cross-reactivity with canine PSMA (and J591) was confirmed by protein analyses on DPC-1, LNCaP, and PC-3 cell lines and IHC of dog vs. human prostate tissue sections. 17G1 stained luminal cells and DPC-1 cancer cells in dog prostates similarly to human luminal and cancer cells of patients and LNCaP xenografts. SPECT/CT imaging revealed low uptake (≤2.1) of both (111)In-17G1 in normal dog prostates and (111)In-IgGs in growing DPC-1 prostate tumors comparatively to (111)In-17G1 uptake of 3.6 increasing up to 6.5 values in prostate with DPC-1 lesions. Images showed a diffused pattern and, occasionally, a peripheral doughnut-shape-like pattern. Numerous sacro-iliac lymph nodes and lung lesions were detected with contrast ratios of 5.2 and 3.0, respectively. The highest values were observed in pelvic bones (11 and 19) of two dogs, next confirmed as PSMA-positive metastases. CONCLUSIONS: This proof-of-concept PSMA-based SPECT/CT molecular imaging detecting primary prostate tumors and metastases in canines with high cancer burden speaks in favor of this large model's utility to facilitate technology transfer to the clinic and accelerate applications of new tools and modalities for tumor staging in patients.

A combination of hemostatic agents may safely replace deep medullary suture during laparoscopic partial nephrectomy in a pig model.

PURPOSE: We assessed whether a combination of the fibrin tissue adhesive Tisseel® (human fibrinogen and thrombin) plus the hemostatic matrix FloSeal® (bovine derived gelatin matrix/human thrombin) could safely replace the conventional deep medullary suture without compromising outcomes. MATERIALS AND METHODS: Laparoscopic mid pole and one-third partial nephrectomy was performed on the right kidney of 12 female pigs. The only difference between the 2 groups of 6 pigs each was the use of a fibrin tissue adhesive plus hemostatic matrix combination in group 2 instead of the deep medullary running suture in control group 1. Renal scans and angiograms were performed at baseline and before sacrifice at 5-week followup. Retrograde in vivo pyelogram was also done. RESULTS: No significant difference was seen in operative parameters or postoperative course between the groups. Renal scans revealed a statistically insignificant trend toward greater uptake loss in group 1 and angiograms showed 3 major vessel occlusions in that group. No active bleeding was detected. Those 3 kidneys had significantly poorer postoperative uptake on renal scan than that of other kidneys (18.6% vs 39.4%, p = 0.013). Only 1 small asymptomatic pseudoaneurysm was noted in group 1. No urine leakage was found in either group. No major vessel occlusion, pseudoaneurysm or urinary complications developed in group 2. CONCLUSIONS: Even after deep one-third partial nephrectomy FloSeal with concurrent Tisseel appeared sufficient to control major medullary vascular injuries and replace the deep medullary conventional suture without compromising operative outcomes. The potential advantages seen during functional and vascular examinations by decreasing the risk of unnecessary segmental vessel occlusion need further clinical evaluation.

Gastric neuroendocrine carcinoma staged and followed with (18)F-FDG PET/CT--a report of 3 cases.

Gastric neuroendocrine carcinomas (NEC) are very rare, aggressive tumors of the stomach that are distinct from the more benign neuroendocrine tumors, sometimes referred to as "gastric carcinoids." We present 3 cases of gastric NEC representing various histological subtypes that were successfully staged and followed with F-FDG PET/CT, impacting therapeutic management in each case.

Amyloidosis in FDG-avid lymph nodes.

Amyloidosis in lymph node that is FDG-avid is an unusual diagnosis. FDG PET/CT showed the presence of multifocal lymphadenopathy mainly axillary with a mesenteric mass. Surgical lymph node biopsy with histological examination confirmed the diagnosis of amyloidosis in a 64-year-old woman with an initial left axillary pain. Amyloidosis should be considered on the differential diagnosis for a FDG-avid lymphadenopathy. Other differential diagnosis usually includes malignancy such as lymphoma or metastatic disease, infection, or sterile inflammation.

Spectrum of malignant renal and urinary bladder tumors on 18F-FDG PET/CT: a pictorial essay.

A wide variety of malignant renal and urinary bladder diseases can be detected on (18)F-FDG PET/CT. Although the PET/CT findings are often nonspecific, the aim of this atlas was to demonstrate that the spectrum of renal and urinary bladder malignancy that can be evaluated with PET/CT is much broader than current medical literature would suggest. PET/CT readers and oncologists should be aware of the variety of urological tumor types that can be detected on PET/CT and some of the patterns of (18)F-FDG uptake that can be observed in these cases.

Spectrum of gastric malignancy on 18F-FDG PET/CT: a pictorial essay.

A wide variety of malignant gastric diseases can be detected, staged, and followed on (18)F-FDG PET/CT. Although the PET/CT findings are often nonspecific and some can be seen in certain benign gastric diseases, the aim of this atlas was to demonstrate that the wide histological spectrum of gastric tumors that can be evaluated, staged, and followed with PET/CT is much broader than current medical literature would suggest. PET/CT readers and oncologists should be aware of the utility of PET/CT in these tumors and the imaging characteristics and patterns of (18)F-FDG uptake that can be demonstrated in these cases.

Spectrum of malignant pleural and pericardial disease on FDG PET/CT.

OBJECTIVE: The purpose of this article is to illustrate a wide spectrum of malignant primary and secondary pleural and pericardial diseases imaged with (18)F-FDG PET/CT. CONCLUSION: A wide variety of malignant pleural and pericardial diseases can be detected, staged, and monitored by FDG PET/CT. Although the PET/CT findings are often nonspecific, the aim of this atlas is to show that the spectrum of pleural and pericardial disease that can be evaluated with PET/CT is much broader than current literature would suggest. PET/CT readers and oncologists should be aware of the wide variety of malignancies that can affect the pleura and pericardium and some of the patterns of FDG uptake that can be observed in these cases.

Compression of the right pulmonary artery by a massive descending aortic aneurysm causing bilateral perfusion defects on pulmonary scintigraphy.

A 67-year-old woman, who presented with a 2 month history of dyspnea, had a ventilation and perfusion lung scan that showed absent perfusion of the entire right lung with normal ventilation, as well as a rounded matched defect in the left lower lung adjacent to midline, suspicious for an aortic aneurysm or dissection. CT pulmonary angiography revealed a massive descending aortic aneurysm compressing the right pulmonary artery as well as the left lung parenchyma, accounting for the bilateral perfusion scan defects. We present the Xe-133 ventilation, Tc-99m MAA perfusion and CT pulmonary angiography imaging findings of this rare case.

Primary peripheral T-cell lymphoma of the colon mimics inflammatory bowel disease: a potential pitfall with F-18 FDG PET/CT imaging.

We present a case of a woman with ulcerative colitis who was referred for an F-18 FDG PET/CT after a suspicious colonoscopy and biopsy. PET/CT showed multiple elongated foci of intense FDG uptake in the colon, a pattern commonly reported with inflammatory bowel disease; however, the possibility of lymphoma was raised. Reevaluation of the biopsies with immunohistochemistry and molecular studies revealed a peripheral T-cell lymphoma and the patient was treated with a total colectomy. In this case, F-18 FDG PET/CT was very useful in determining the extent of the disease. This case also highlights a potential pitfall whereby the tubular and multifocal appearance of this lymphoma subtype can mimic the appearance of bowel involved by inflammatory bowel disease especially on novel techniques such as PET/CT enterography and PET/CT colonography.

Rapidly growing complex fibroadenoma with surrounding ductal hyperplasia mimics breast malignancy on serial F-18 FDG PET/CT imaging.

A 30-year-old woman was referred for an F-18 fluorodeoxyglucose (FDG) PET/CT to rule out lymphoma, and was found to have an incidental FDG-avid right breast nodule that grew significantly in size and FDG uptake on a subsequent scan, raising suspicion of a growing breast malignancy. Histologic evaluation showed a complex fibroadenoma with adenosis and surrounding ductal hyperplasia. Although variable F-18 FDG uptake in fibroadenomas has been described, a distinction between simple and complex fibroadenomas has not been made in the PET literature, even though complex fibroadenomas have a higher propensity to develop into malignancies. This case shows that a rapidly growing complex fibroadenoma can mimic a breast malignancy on serial F-18 FDG PET/CT scans, showing significant increase in both size and FDG-avidity on follow-up studies.

Malignant epithelioid hemangioendothelioma of the lower extremity: staging with F-18 FDG PET/CT.

A 36-year-old woman presented with a 5-month history of a growing left thigh mass, causing difficulty walking. Biopsy revealed a malignant epithelioid hemangioendothelioma (EHE), and the patient was referred for a staging F-18 FDG PET/CT that showed intense FDG uptake in the thigh mass, but no FDG-avid local lymph nodes or distant metastases. A few reports have noted the usefulness of F-18 FDG PET/CT imaging in the staging of EHEs in the lung, liver, and bone marrow. This rare study highlights the usefulness of F-18 FDG PET/CT in the staging of malignant EHE of the soft tissues of the extremities.

Histiocytic sarcoma involving lymph nodes: imaging appearance on gallium-67 and F-18 FDG PET/CT.

This report of an 82-year-old man who presented with a 3-week history of an enlarging left axillary mass and mild fevers, highlights the usefulness of both gallium-67 and F-18 FDG PET/CT imaging in the staging of histiocytic sarcoma. While PET/CT was superior in determining the extent of the disease, gallium can be used to help stage the disease in centers where PET/CT is not available.

Hodgkin lymphoma post-transplant lymphoproliferative disorder following pediatric renal transplant: serial imaging with F-18 FDG PET/CT.

Post-transplant lymphoproliferative disorder (PTLD) occurs in 1.2% of pediatric renal transplant patients, and is frequently Epstein-Barr Virus mediated. Hodgkin Lymphoma PTLD is the rarest of the 4 types of PTLDs recognized by the World Health Organization, with an incidence of <4% of all PTLD patients. It has a distinct clinical course and treatment from all other types of PTLD. This is a case of a 16-year-old girl who had a renal transplant in 2000 due to Moya Moya disease. Her first F-18 FDG PET/CT done in 2006 showed mildly FDG-avid mediastinal adenopathy (histologically nonspecific reactive nodes), however in 2009, after presenting with fevers, a repeat PET/CT showed extensive intensely FDG-avid disease. Biopsy of a supraclavicular node identified Hodgkin Lymphoma PTLD. The patient was treated with chemotherapy and reimaged, showing excellent response to therapy. In contrast, classic PTLD is treated by withdrawal of immunosuppression and administration of Rituximab. F-18 FDG PET/CT is known to be very useful in the staging and monitoring of response to therapy in the setting of classic PTLD. In this case, serial F-18 FDG PET/CT scans proved very useful in the evaluation and follow-up of the rare and distinct Hodgkin Lymphoma PTLD subtype.

Myeloid sarcoma presenting as an anterior mediastinal mass invading the pericardium: Serial Imaging With F-18 FDG PET/CT.

Myeloid sarcoma is a tumor formed by extramedullary accumulation of myeloblasts or immature myeloid cells. These tumors can develop in lymphoid organs, bone, skin, soft tissue, and other organs, and may precede or occur concurrently with acute myeloid leukemia. This is a case of a 42-year-old man who presented with a 2-week history of cough and shortness of breath on exertion. A computed tomography (CT) scan showed a large mediastinal mass and pericardial effusion. An F-18 fluorodeoxyglucose positron emission tomography-CT scan showed intense fluorodeoxyglucose (FDG) uptake in the mediastinal mass with invasion of the parietal pericardium. Biopsy of the mediastinal mass and pericardium revealed myeloid sarcoma. The pericardial effusion was drained and the patient was treated with high-dose cytosine arabinoside (HiDAC) chemotherapy. A follow-up positron emission tomography-CT was done 2 months after the last cycle, showing poor response to therapy and significant progression of disease with invasion through the anterior chest wall. Myeloid sarcoma can be added to the differential diagnosis of F-18 FDG avid anterior mediastinal masses, as well as F-18 FDG uptake in the pericardium.