Review of Extraskeletal Activity on Tc-99m Methylene Diphosphonate Bone Scintigraphy and Value of Cross-Sectional and SPECT-CT Imaging Correlation.

Recognizing the different mechanisms and imaging appearance of extraskeletal Tc-99m methylene diphosphonate uptake enhances the diagnostic value of bone scan interpretation. In this article, we present a pictorial review of the different mechanisms of extraskeletal Tc-99m methylene diphosphonate uptake on bone scintigraphy including neoplastic, inflammatory, ischemic, traumatic, excretory, and iatrogenic. We also illustrate through case examples the added value of correlation with cross-sectional and single photon emission computed tomography and computed tomography imaging in localizing and characterizing challenging cases of extraskeletal uptake.

Metachronous presentation of small-cell rectal carcinoma on an 18F-FDG PET/CT follow-up for follicular lymphoma.

We present a case of a 60-year-old woman with history of follicular lymphoma in remission presenting for an 18F-fluorodeoxyglucose positron emission tomography/computed tomography for suspected recurrence. Imaging showed widespread hypermetabolic lymphadenopathy consistent with lymphoma recurrence. A 3-month 18F-fluorodeoxyglucose positron emission tomography/computed tomography follow-up after chemotherapy showed resolution of hypermetabolic lymphadenopathy but multiple new hepatic lesions and a new subtle rectal lesion. Biopsies of both hepatic and rectal lesions revealed new diagnosis of metachronous high-grade small-cell carcinoma.

Chronic Nephropathy from Dietary Hyperoxaluria: Sustained Improvement of Renal Function after Dietary Intervention.

A 56-year-old man with stable chronic kidney disease (CKD) for two years following a single episode of calcium oxalate urolithiasis developed progressive elevation of his serum creatinine concentration. Urinalysis revealed pyuria and white cell casts, a few red blood cells, minimal proteinuria, and no crystals. Urine culture was sterile. Gallium scintigraphy was consistent with interstitial nephritis. Proton pump inhibitor intake was discontinued, and a short course of oral corticosteroids was initiated. Percutaneous kidney biopsy, performed because of the continued deterioration of renal function to a minimum estimated glomerular filtration rate (eGFR) value of 15 mL/min per 1.73 m2 and persistent pyuria, revealed deposition of oxalate crystals in the tubules and interstitium, pronounced tubular changes, and interstitial nephritis and fibrosis. Urinary oxalate excretion was very high, in the range usually associated with primary hyperoxaluria. However, investigations for primary or enteric hyperoxaluria were negative. He reported a diet based on various nuts high in oxalate content. Estimated oxalate content in the diet was, for years, approximately four times higher than that in the average American diet. The institution of a diet low in oxalates resulted in the rapid normalization of urinary oxalate excretion and urinary sediment and in the slow, continuous improvement of renal function to near normal levels (eGFR 59 mL/min/1.73 m2) before his death from a brain malignancy 3.5 years later. The manifestations of nephropathy secondary to dietary hyperoxaluria, including the urine findings, can be indistinguishable from other types of interstitial nephritis. The diagnosis of dietary hyperoxaluria requires careful dietary history and a kidney biopsy. Identifying dietary hyperoxaluria as the cause of CKD is important because the decrease in dietary oxalate intake without any other measures can lead to sustained improvement in renal function.

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.

Nephropathy in dietary hyperoxaluria: A potentially preventable acute or chronic kidney disease.

Hyperoxaluria can cause not only nephrolithiasis and nephrocalcinosis, but also renal parenchymal disease histologically characterized by deposition of calcium oxalate crystals throughout the renal parenchyma, profound tubular damage and interstitial inflammation and fibrosis. Hyperoxaluric nephropathy presents clinically as acute or chronic renal failure that may progress to end-stage renal disease (ESRD). This sequence of events, well recognized in the past in primary and enteric hyperoxalurias, has also been documented in a few cases of dietary hyperoxaluria. Estimates of oxalate intake in patients with chronic dietary hyperoxaluria who developed chronic kidney disease or ESRD were comparable to the reported average oxalate content of the diets of certain populations worldwide, thus raising the question whether dietary hyperoxaluria is a primary cause of ESRD in these regions. Studies addressing this question have the potential of improving population health and should be undertaken, alongside ongoing studies which are yielding fresh insights into the mechanisms of intestinal absorption and renal excretion of oxalate, and into the mechanisms of development of oxalate-induced renal parenchymal disease. Novel preventive and therapeutic strategies for treating all types of hyperoxaluria are expected to develop from these studies.

Favorable outcome of Fournier gangrene in two patients with diabetes mellitus on continuous peritoneal dialysis.

Fournier gangrene (FG), a form of necrotizing fasciitis of the perineum and genitals, with high morbidity and mortality in the general population, carries the additional risk of involvement of the peritoneal catheter tunnel and peritoneal cavity in patients on chronic peritoneal dialysis (PD). We describe two men with diabetes who developed FG in the course of PD. Computed tomography showed no extension of FG to the abdominal wall, and spent peritoneal dialysate was clear in both patients. Broad-spectrum antibiotic therapy with anaerobic coverage and early aggressive debridement followed by negative-pressure wound therapy and repeated debridement led to improvements in clinical status in both cases. Surgical closure and healing of the wound was achieved in one patient; the wound of the second patient is healing, but remains open. Both patients experienced prolonged hospitalization, with a serious decline in nutrition status. In patients on PD, FG can be treated successfully. However, additional measures are required to evaluate for potential involvement of the PD apparatus and the peritoneal cavity in the infectious process; and prolonged hospitalization, worsening nutrition, and multiple surgical interventions can result.

SPECT/CT localization of oral radioiodine activity: a retrospective study and in-vitro assessment.

PURPOSE: We sought to further localize radioiodine activity in the mouth on post-thyroid cancer therapy imaging using single-photon emission computed tomography/computed tomography (SPECT/CT). MATERIALS AND METHODS: We retrospectively reviewed all patients (58) who underwent thyroid cancer therapy with iodine-131 (131I) at our institution from August 2009 to March 2011 whose post-therapy radioiodine imaging included neck SPECT/CT. A small group (six) of diagnostic 131I scans including SPECT/CT was also reviewed. Separately, we performed in-vitro 131I (sodium iodide) binding assays with amalgam and Argenco HP 77 (77% dental gold alloy) as proof of principle for these interactions. RESULTS: Of the 58 post-therapy patients, 45 (78%) had undergone metallic dental restorations, and of them 41 (91%) demonstrated oral 131I activity localizing preferentially to those restorations. It was observed that radioiodine also localized to other dental restorations and to orthodontic hardware. Gum-line activity in edentulous patients suggests radioiodine interaction with denture adhesive. In vitro, dental amalgam and Argenco HP 77 bound 131I in a time-dependent manner over 1-16 days of exposure. Despite subsequent washings with normal saline, significant 131I activity (maximally 12% for amalgam and 68% for Argenco HP 77) was retained by these metals. Subsequent soaking in a saturated solution of potassium iodide partially displaced 131I from amalgam, with near-total displacement of I from Argenco HP 77. CONCLUSION: SPECT/CT shows that radioiodine in the oral cavity localizes to metallic dental restorations. Furthermore, in-vitro studies demonstrate partially reversible binding of 131I to common dental metals.

Q Fever masquerading as prostate cancer metastases.

We report a case of Q fever demonstrated on (99m)Tc methylene diphosphonate bone scan and fluorodeoxyglucose (FDG) PET/CT. A 66-year-old man with newly diagnosed, low-grade prostate cancer presented with abdominal and bone pain. Bone scan revealed multiple lesions suspicious for prostate cancer metastases. Because of liver abnormalities on noncontrast CT, an FDG PET/CT was performed and demonstrated FDG-avid sclerotic bone lesions, infiltrative liver disease, and retroperitoneal adenopathy. This appearance, thought unusual for low-grade prostate cancer, prompted extensive clinical evaluation for several months. Liver and iliac bone biopsies showed noncaseating granulomas without neoplasia. Extensive serologic evaluation eventually demonstrated elevated Q fever titers.

Evaluation of new data processing algorithms for planar gated ventriculography (MUGA).

Before implementing one of two new LVEF radionuclide gated ventriculogram (MUGA) systems, the results from 315 consecutive parallel patient studies were evaluated. Each gamma-camera acquisition was simultaneously processed by semi-automatic Medasys Pinnacle and by fully-automatic and semi-automatic Philips nuclear medicine computer systems. The Philips systems yielded LVEF results within +/- 5 LVEF percentage points of the Medasys system in fewer than half of the studies. The remaining values were higher or lower than those from the long-used Medasys system. These differences might have changed cancer patient chemotherapy clinical decisions in 54 cases (17% of studies) for one of the systems. As a result, our institution elected not to implement either new system.