Liver Trapping of 99mTc Macroaggregated Albumin During Ventilation/Perfusion Scintigraphy in a Patient With Superior Vena Cava Stenosis as Demonstrated by SPECT/CT

Unexpected Vertebral Bodies Trapping of 99mTc-Macroaggregated Albumin During Lung Perfusion Scintigraphy in a Patient With Collateral Paravertebral Venous System

ABSTRACT

A 35-year-old woman was referred to our nuclear medicine center for a ventilation and perfusion (VQ) pulmonary scintigraphy to detect pulmonary embolism. She was treated with low-molecular-weight heparin following a proximal venous thrombosis of the right upper limb and had a previous history of an infiltrating ductal carcinoma of the right breast. Surprisingly, the VQ scintigraphy showed uptake of 99mTc-MAA in several superior vertebrae. A contrast-enhanced CT scan revealed a dilated collateral paravertebral venous system due to the deep vein thrombosis extended from superior vena cava to brachiocephalic trunk. 99mTc-MAA was trapped through the dilated vertebral venous system.

Focal Liver 18F-FDG Uptake in a Patient Who Underwent Thrombolysis for Brachiocephalic and Subclavian Thrombosis: A Potential Pitfall

ABSTRACT

A 19-year-old woman presented with a primary mediastinal B-cell lymphoma invading the superior vena cava with associated thrombosis of the left brachiocephalic and subclavian vein. She underwent thrombolysis followed by chemotherapy. The midtreatment 18F-FDG PET/CT demonstrated important regression of the primary mediastinal B-cell lymphoma, but showed intense focal hepatic uptake in segment IV, without a corresponding lesion on ultrasonography, non-contrast-enhanced low-dose CT, and MRI. This focal uptake disappeared on a subsequent 18F-FDG PET/CT study when the radiotracer was injected in the foot, suggesting an anomalous venous return pathway that persisted despite thrombolysis.

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.