Abnormal Tc-99m MAA accumulation

Image findings are described in two patients who received radiochemically impure Tc-99m MAA radiopharmaceutical preparations. The cases are completely separate and show clinically the presence of hydrolyzed-reduced technetium (TcO2) in a radiopharmaceutical product.     

Breast-milk radioactivity after a Tc-99m DTPA aerosol/Tc-99m MAA lung study

Measurements were made of the concentration of Tc-99m activity in samples of breast milk following an administration of Tc-99m DTPA aerosol for a lung ventilation image and one of Tc-99m MAA for lung perfusion. The activity was 222 nCi/ml of milk (8.2 kBq/ml) at 2 hr after the MAA injection, and it was found to be excreted exponentially with an effective half-life of 4.6 hr. There was a small incorporation of Tc-99m into breast-milk protein. We conclude that the combined use of these two Tc-99m agents did not indicate the interruption of breast feeding beyond 24 hr after administration of the MAA, and that for an aerosol ventilation study alone, breast feeding need not be interrupted for more than 4 hr after the test.     

Tc-99m dextran and Tc-99m HIG findings in patients with ulcerative colitis.

PURPOSE: Various radionuclide methods have been studied for the evaluation of the disease activity and extent of ulcerative colitis and other protein-losing enteropathies. Recently, Tc-99m dextran and Tc-99m human immunoglobulin (HIG) have been used to detect inflammation and protein loss into the intestine, but only a few studies have been reported with these agents. MATERIALS AND METHODS: In this study, Tc-99m dextran and Tc-99m HIG were used to evaluate disease activity and extent in patients with ulcerative colitis. These agents were used in 12 patients with active disease and in five patients in remission, and five healthy control participants also were included. RESULTS: Large bowel activity was detected in 11 of the 12 patients with active ulcerative colitis using Tc-99m dextran and in 10 patients using Tc-99m HIG. Fifty-eight bowel segments were found to be active with endoscopy, 39 with Tc-99m dextran, and 31 with Tc-99m HIG. No intestinal activity was detected in the control participants. Grade 1 activity localization in the large bowel was detected in three patients with ulcerative colitis in remission using Tc-99m dextran and in one patient using Tc-99m HIG. CONCLUSION: Tc-99m dextran is more sensitive for detecting disease activity and extent than is Tc-99m HIG.     

Hepatic localization of Tc-99m MAA during lower extremity venography

Hepatic localization of macroaggregated albumin particles has been observed previously in both superior and inferior vena cava obstruction. These reports have described focal regional hepatic uptake in porta hepatis or the left hepatic lobe in cases of SVC and IVC obstruction as well as global hepatic uptake in IVC obstruction. In this report of an unusual case of hepatic uptake of MAA during lower extremity venography, the entire liver and lungs were simultaneously visualized, presumably due to portal-to-systemic collateral flow pathways in the presence of inferior vena cava obstruction.     

Hepatic localization of Tc-99m MAA in inferior vena cava obstruction

Two cases of hepatic localization of Tc-99m MAA following injection through the lower extremity venous system are presented. These cases show two different patterns of hepatic uptake, which are related to the likely routes of ilioportal shunting in inferior vena cava obstruction.     

MR imaging of partial anomalous pulmonary venous connections

Magnetic resonance imaging was performed on 11 patients with partial anomalous pulmonary venous connections (PAPVC). Ten of these patients also had echocardiographic examinations, eight of which included color-flow Doppler studies. The diagnosis of PAPVC was confirmed in each of these patients by surgery or angiography. Fourteen anomalous pulmonary venous connections were identified, 10 involving the right upper lobe pulmonary vein and 4 involving the left upper lobe pulmonary vein. This retrospective review demonstrated that all 14 anomalous venous connections were correctly identified by MR imaging, whereas only 8 of 13 (62%) were identified by echocardiography. With MR, 89% of all the pulmonary veins and 93% of the anomalous pulmonary veins were visualized on axial images, while 41% of all pulmonary veins and 71% of anomalous veins were seen on coronal MR images. There were five atrial septal defects (ASDs), four of the sinus venous type and one of the septum secundum type. All five ASDs were correctly identified with MR imaging; three of four ASDs were identified with echocardiography. We conclude that MR imaging provides an accurate noninvasive method of depicting the anatomic abnormalities associated with PAPVC.     

Generation of parametric images during routine Tc-99m PYP inhalation/Tc-99m MAA perfusion lung scintigraphy. Technical note.

A simple technique is described for generating ventilation/perfusion ratio and perfusion/ventilation ratio images from the posterior Tc-99m PYP aerosol inhalation and Tc-99m MAA perfusion images obtained during routine lung scintigraphy. These images highlight areas of ventilation/perfusion incongruence--mismatch or reverse mismatch--that may sometimes be difficult to detect on conventional images.     

Hepatic and splenic uptake of Tc-99m HDP in multiple myeloma: additional findings on Tc-99m MIBI and Tc-99m sulfur colloid images

The authors present a case of multiple myeloma with intense hepatic and splenic uptake on Tc-99m HDP bone scan and discuss its clinical implications and possible uptake mechanisms. Tc-99m MIBI and Tc-99m sulfur colloid were used to demonstrate bone marrow involvement and focal lesions of multiple myeloma.     

Liver and vertebral uptake of Tc-99m macroaggregated albumin (MAA)

An unusual phenomenon during lung scintigraphy is presented. Besides visualization of the lungs, accumulation of Tc-99m macroaggregated albumin (MAA) was seen in a small part of the liver and in and around several thoracic vertebrae. Contrast-enhanced radiographic computed tomography revealed extensive collateral pathways, which were caused by a partially obstructed superior vena cava. Shunting of systemic venous blood flow through chest wall veins to the portal system was responsible for accumulation of MAA in the liver. Retrograde blood flow through dilated thoracic vertebral veins resulted in visualization of the bone marrow.