Gregory Ravizzini

Prognostic Value of Baseline [18F] Fluorodeoxyglucose Positron Emission Tomography and 99mTc-MDP Bone Scan in Progressing Metastatic Prostate Cancer

Purpose: To compare the diagnostic and prognostic value of [18F] fluorodeoxyglucose positron emission tomography (FDG-PET) and bone scans (BS) in the assessment of osseous lesions in patients with progressing prostate cancer. Experimental Design: In a prospective imaging trial, 43 patients underwent FDG-PET and BS prior to experimental therapies. Bone scan index (BSI) and standardized uptake value (SUV) on FDG-PET were recorded. Patients were followed until death (n = 36) or at least 5 years (n = 7). Imaging findings were correlated with survival. Results: Osseous lesions were detected in 39 patients on BS and 32 on FDG-PET (P = 0.01). Follow-up was available for 105 FDG-positive lesions, and 84 (80%) became positive on subsequent BS. Prognosis correlated inversely with SUV (median survival 14.4 versus 32.8 months if SUVmax > 6.10 versus ≤ 6.10; P = 0.002) and BSI (14.7 versus 28.2 months if BSI > 1.27 versus < 1.27; P = 0.004). Only SUV was an independent factor in multivariate analysis. Conclusion: This study of progressive prostate cancer confirms earlier work that BSI is a strong prognostic factor. Most FDG-only lesions at baseline become detectable on follow-up BS, suggesting their strong clinical relevance. FDG SUV is an independent prognostic factor and provides complementary prognostic information. Clin Cancer Res; 16(24); 6093–99. ©2010 AACR.

POSITRON EMISSION TOMOGRAPHY DETECTION OF METASTATIC PENILE SQUAMOUS CELL CARCINOMA

A 58-year-old white man presented elsewhere with small white lesions on the glans of the penis in 1992. History included circumcision at age 16 years and multiple sequential rigid dilations for urethral stricture. Balanitis xerotica obliterans was diagnosed and treatment was local. The area became sore 5 years later and a biopsy revealed squamous cell carcinoma. The patient underwent Mohs’ procedure and was disease-free for the next 15 months when a recurrent lesion, just ventral to the meatus, was positive for squamous cell carcinoma. No palpable inguinal adenopathy was identified and a chest x-ray was negative for metastatic disease. The patient was referred to us and we recommended partial penectomy. In 1998 he underwent a wide wedge resection of the glans penis, meatus and distal urethra with plastic reconstruction of the distal penile shaft to accommodate a new meatus. Pathological examination confirmed invasive, well differentiated, keratinizing squamous cell carcinoma. All surgical margins were free of tumor. A firm mass in the left groin was palpated 2 years later. Computerized tomography (CT) of the pelvis identified a 3.5 3 2.5 cm. heterogeneous left inguinal mass consistent with nodal spread of penile carcinoma. No intravenous contrast material was given due to iodine allergy. Left superficial and deep inguinal lymph node dissection revealed metastatic keratinizing squamous cell carcinoma in 2 of 12 superficial lymph nodes. The largest positive node was 3 cm. and showed extracapsular invasion. All resected deep nodes were negative. The postoperative course was complicated by an increased drainage from the Jackson-Pratt drain, increased wound swelling and wound separation requiring daily packing and home nursing care. The patient noticed a small single nodule on the left anterior upper thigh 2 months after discharge from the hospital. Abdominal and pelvic CT without intravenous contrast material revealed multiple surgical clips and ill defined soft tissue at the left groin surgical site (fig. 1, A). Inferiorly in the left groin, there was a 4.5 3 4.5 cm. fluid attenuation lesion (fig. 1, B). It was difficult to discern between recurrent disease versus postoperative changes. CT of the chest showed multiple bilateral pulmonary nodules suspicious for metastatic disease. It is noteworthy that no hilar adenopathy was visualized. Whole body positron emission tomography after the intravenous injection of 11.39 mCi. F-18 fluorodeoxyglucose demonstrated multiple foci of increased fluorodeoxyglucose activity in the left groin, left upper thigh, left iliac chain and right groin (fig. 2). One of the abnormal areas of fluorodeoxyglucose activity in the left groin had central decreased uptake, which corresponded to the fluid collection on CT (fig. 2). In addition, there were punctuate foci of abnormal increased fluorodeoxyglucose uptake in the chest. A single focus was seen in the left upper lobe, which corresponded to a nodule on CT. Foci of increased activity were noted in both hila suspicious for metastatic disease, although no lymphadenopathy was visualized on CT.

Plasmablastic Lymphoma in an Immunocompetent Patient

An 84-year-old female was admitted to the State University of New York University Hospital (Syracuse, NY) with complaints of persistent right hip pain for longer than 1 month. Her past medical history was significant for Wolff-Parkinson-White syndrome and osteoarthritis. The physical exam was unremarkable except for some decreased range of motion of the right hip. Computed tomography scan of the abdomen and pelvis showed a massive (8.5 7.0 cm), asymmetric, and heterogeneous mass in the right psoas muscle (Fig 1). Radiologically, the mass appeared to be a well-circumscribed hematoma. Biopsy showed a diffuse infiltrate of large neoplastic cells with plasmablastic (cells with rounded nuclei, coarser chromatin, and smaller two to three nucleoli) and immunoblastic morphology (cells with vesicular enlarged nuclei and single prominent nucleolus, Fig 2A). High proliferative index, frequent apoptosis, and focal necrosis were seen. The neoplastic cells were essentially CD20 negative (Fig 2B) and showed strong positivity with CD138 (Fig 2C) and CD79a (Fig 2D). Additionally kappa light chain restriction was noted by in situ hybridization (Figs 3A, kappa; 3B, lambda). Multiple myeloma oncogene-1 (Fig 3C) showed diffuse strong nuclear positivity and paired box gene-5 (PAX-5; Fig 3D) was positive in more than 50% of the tumor cells. Pancytokeratin, markers for breast carcinoma (GCDFP-15 and mammoglobulin), lung malignancy (TTF-1 and CK-7), melanoma (S-100 and MART-1) and other lymphoid markers (CD10, CD3, CD4, CD8, CD56, CD68, Bcl-6, ALK, and CD30) were all negative. Staining for Epstein-Barr virus (EBV) both by immunohistochemistry (EBV latent member protein 1) and in situ hybridization (EBV-encoded RNA) was also negative. Further staging work-up including computed tomography of the thorax and bone scan were negative. There were no other mass lesions or lymphadenopathy. Serum beta-2 microglobulin was mildly elevated at 2.8 mg/L (normal, 2.3 mg/L), serum albumin was low normal at 3.5 g/dL (normal, 3.4 to 4.8 g/dL), and lactate dehydrogenase was elevated at 800 IU/L. Serum and urine protein electrophoresis were normal without presence of a paraprotein or free light chains. Bone marrow examination did not show any morphologic or phenotypic evidence of plasma cell dyscrasia or lymphoma. Enzyme-linked immunosorbent assay for HIV was negative. There was no history of use of immunosuppressive medications. Based on the clinical presentation, morphology and immunophenotype, the patient was diagnosed as having a extramedullary plasmablastic tumor most consistent with large B-cell lymphoma with plasmablastic differentiation. The patient was started on radiotherapy to palliate pain with the intent of subsequent multiagent chemotherapy. Unfortunately, she developed bowel ischemia and infarction in the radiation field. Her condition subsequently deteriorated and she died 1 month after her admission. Plasmablastic lymphoma (PBL) is a distinctive B-cell neoplasm that shows diffuse proliferation of large neoplastic cells, most of which resemble B-immunoblasts and have immunophenotype of plasma cells. PBL was originally described as a rare variant of diffuse large B cell lymphoma (DLBCL) involving the oral cavity and occurring in the clinical setting of HIV and latent EBV infection. PBL accounts for 2.6% of all HIV-related non-Hodgkin’s lymphomas. The prognosis is poor, with death occurring between 1 and 24 months after diagnosis (average survival time, 6 months). PBL has been described, less commonly, in extraoral locations and immunocompetent settings. Current evidence suggests that DLBCL with plasmablastic differentiation represents a clinically heterogeneous spectrum with different clinicopathologic characteristics representing distinct entities. Important subtypes include PBL of oral mucosa type, PBL with plasmacytic

F-18 FDG uptake in subcutaneous panniculitis-like T-cell lymphoma.

A 41-year-old male presented to an outside institution complaining of a lump under the skin of his right abdomen. CT scan reported ill-defined densities with streaky inflammatory changes in the anterior abdominal wall. Excisional biopsy of the subcutaneous adipose tissues of the right anterior abdominal wall was consistent with subcutaneous panniculitis-like T-cell lymphoma. Flow cytometry demonstrated CD3+ and CD8+ population. On immunohistochemistry, most lymphoid cells were positive for CD3, CD45RO, CD5, and CD8 and negative for CD10, CD43, CD4, CD20, and CD56. The MIB-1 proliferative index was 30%. Bone marrow biopsy revealed no evidence of lymphomatous involvement.

Efficiency comparison between 99mTc-tetrofosmin and 99mTc-sestamibi myocardial perfusion studies

The purpose of this investigation was to compare the efficiency of two different imaging protocols using two different clinically available 99mTc labelled myocardial perfusion tracers. One thousand one hundred and thirty-four imaging studies were performed prospectively, using either 99mTc-tetrofosmin or 99mTc-sestamibi, alternating the use of each tracer for a total period of 8 months. 99mTc-tetrofosmin rest studies were performed with injections of 259 MBq-370 MBq and imaging 30 min later. Exercise studies were performed with injections of 777 MBq-1.11 GBq and imaging 20 min later. 99mTc-sestamibi studies used doses similar to those in the 99mTc-tetrofosmin studies. Imaging followed a standard procedure, at 60 min after rest injection, and 30 min after exercise. For patients undergoing pharmacological stress testing,99mTc-sestamibi was imaged 45 min after injection and 99mTc-tetrofosmin was imaged 30 min after injection. Variables analysed were (1) injection-to-imaging time for the procedure, and (2) the number of repeated scans because of extra cardiac activity. The completion time for the rest study was significantly shorter for 99mTc-tetrofosmin compared to 99mTc-sestamibi (47.7±21.7 min vs 74.3±25.8 min P<0.0001). Likewise, the total study time was shorter for 99mTc-tetrofosmin compared to 99mTc-sestamibi (90±32.7 min vs 124±37 min, P<0.0001). More importantly, the number of repeated scans was higher with 99mTc-sestamibi compared to 99mTc-tetrofosmin, 21.4% vs 10%, P = 0.001 for rest studies and 19.7% vs 7.9% P = 0.1 for rest and stress. It was concluded that, using a same day rest/stress protocol, 99mTc-tetrofosmin provided higher patient throughput with fewer repeat scans. These factors may be considered for efficiency improvement in nuclear cardiology laboratories using 99mTc perfusion tracers.

Whole-body Tc-99m sestamibi scintigraphy in the follow-up of differentiated thyroid carcinoma

PURPOSE This study evaluated the potential of Tc-99m sestamibi whole-body scan (WBMIBI) as an alternative to whole-body I-131 scan (WBI) for the follow-up of patients with differentiated thyroid carcinoma. MATERIALS AND METHODS We evaluated 99 consecutive patients with differentiated thyroid carcinoma who had total or nearly total thyroidectomy followed by an ablative dose of I-131 (86 women, 13 men; mean age, 44 +/- 12 years). WBMIBI was performed and serum thyroglobulin (TG) levels were obtained at least 6 months after I-131 treatment. All persons were receiving levothyroxine therapy. RESULTS From the total of 110 studies performed, WBMIBI and TG were in agreement in 96% and discordant in 4%. From the 27 crossed studies (WBMIBI x TG) with at least one abnormal result, 16 were compared with WBI. In four cases, the WBI did not reveal functioning thyroid tissue when both TG and WBMIBI indicated tumoral activity. In one case of pulmonary metastasis confirmed by chest radiographs, with a normal TG value, the results of both WBMIBI and WBI were positive. CONCLUSIONS WBMIBI should be considered as a scintigraphic method in the follow-up of differentiated thyroid carcinoma. This technique can show the sites of tumoral activity with optimal image resolution, particularly in those with abnormal TG and negative WBI results, and it is a potentially valuable tool in patients with anti-TG antibodies. The WBI in patients having ablation should be reserved only for therapy planning.

Central line injection artifact simulating paratracheal adenopathy on FDG PET imaging

A 58-year-old man was referred for an F-18 FDG PET study to evaluate for malignancy after thoracentesis demonstrated a hemorrhagic, lymphocyte-predominant exudative effusion. The PET scan demonstrated right paratracheal uptake suspicious for adenopathy, yet the CT scan did not show enlarged lymph nodes. A coiled central line was noted in the superior vena cava (SVC). Repeat PET imaging with injection through a peripheral line failed to demonstrate the abnormality, confirming the artifactual nature of the uptake. The use of central lines for tracer injection could lead to artifacts and, therefore, should be avoided.

The use of PET/CT in prostate cancer

BackgroundPositron emission tomography/computed tomography (PET/CT) has recently emerged as a promising diagnostic imaging platform for prostate cancer. Several radiolabelled tracers have demonstrated efficacy for cancer detection in various clinical settings. In this review, we aim to illustrate the diverse use of PET/CT with different tracers for the detection of prostate cancer.MethodsWe searched MEDLINE using the terms ‘prostate cancer’, ‘PET’, ‘PET/CT’ and ‘PET/MR’). The current review was limited to 18F-NaF PET/CT, choline-based PET/CT, fluciclovine PET/CT and PSMA-targeted PET/CT, as these modalities have been the most widely adopted.ResultsNaF PET/CT has shown efficacy in detecting bone metastases with high sensitivity, but relatively low specificity. Currently, choline PET/CT has been the most extensively studied modality. Although having superior specificity, choline PET/CT suffers from low sensitivity, especially at low PSA levels. Nevertheless, choline PET/CT was found to significantly improve upon conventional imaging modalities (CIM) in the detection of metastatic lesions at biochemical recurrence (BCR). Newer methods using fluciclovine and PSMA-targeted radiotracers have preliminarily demonstrated great promise in primary and recurrent staging of prostate cancer. However, their superior efficacy awaits confirmation in larger series.ConclusionsPET/CT has emerged as a promising staging modality for both primary and recurrent prostate cancer. Newer tracers have increased detection accuracies for small, incipient metastatic foci. The clinical implications of these occult PET/CT detected disease foci require organized evaluation. Efforts should be aimed at defining their natural history as well as responsiveness and impact of metastasis-directed therapy.

Gallium-68 in Medical Imaging

Over the past several years, Positron Emission Tomography (PET) imaging agents labeled with ;68Gallium (68Ga) have undergone a significant increase in clinical utilization. 68Ga is conveniently produced from a germanium-68/gallium-68 (68Ge/68Ga) generator. Because of the compact size and ease of use of the generator, 68Ga labeled compounds may be more cost-effective than PET radioisotopes that are cyclotron-produced. The convenient half-life of 68Ga (T1/2=68 min) provides sufficient radioactivity for various PET imaging applications, while delivering acceptable radiation doses to patients. This chapter summarizes the emerging clinical utilization of 68Ga-based radiotracers in medical imaging.

Increased 18F-FDG Uptake Associated With Gastric Banding Surgical Mesh on PET/CT.

Surgical mesh was used in the 1980s and early 1990s for vertical banded gastroplasty as treatment for morbid obesity. This procedure was replaced by the more popular laparoscopic gastric banding in the mid-1990s. Surgical mesh, commonly used in hernioplasty, has been associated with increased F-FDG uptake related to an inflammatory foreign body reaction and is a known cause of false-positive PET scans. We present a case of increased F-FDG uptake related to surgical mesh in a patient who had undergone vertical banded gastroplasty.