Review of diagnostic uses of shunt fraction quantification with technetium-99m macroaggregated albumin perfusion scan as illustrated by a case of Osler-Weber-Rendu syndrome

Lobectomy for Pulmonary Arteriovenous Fistula in a Patient With Rendu-Osler-Weber Disease: A Case Report

BACKGROUND

Rendu-Osler-Weber disease (Osler's disease) is the most common cause of pulmonary arteriovenous fistula. We report a case of pulmonary arteriovenous fistula associated with Osler's disease that was treated by lobectomy.

CASE REPORT

A 44-year-old man with Osler's disease presented with respiratory distress. Computed tomography showed a pulmonary arteriovenous fistula, which had a 26-mm-long diameter in S6 of the left lung. Transcatheter treatment had a high risk of recurrence, and surgery was indicated. The pulmonary arteriovenous fistula was found at the beginning of A6. A6 and the basilar artery were cut together with a stapler. The postoperative course was uneventful, and respiratory distress symptoms improved with no recurrence.

CONCLUSION

We report a case of pulmonary arteriovenous fistula caused by Osler's disease treated by lobectomy. Although transcatheter treatment is the mainstream treatment for pulmonary arteriovenous fistulas, surgical resection may be effective depending on the size of the lesion.

Imaging in hepatopulmonary syndrome-case report. A multicenter approach during the coronavirus pandemic

A 60-year-old lady with alcoholic liver disease developed central cyanosis and orthodeoxia. A technetium-99m macro-aggregated albumin lung perfusion scan and contrast echocardiogram were performed. A 13% right to left shunt was calculated from the macro-aggregated albumin scan. There were more bubbles in the left heart than the right at the end of the contrast echocardiogram. Hepatopulmonary syndrome was therefore diagnosed. The patient had a liver transplant five days after these investigations. Further discussion about hepatopulmonary syndrome will be provided. Normally, macro-aggregated albumin scans are performed in few centers, however as this was at the height of the coronavirus pandemic, the scan needed to be performed locally to reduce the chance of the patient getting coronavirus. Local radiographers were remotely instructed on conducting the macro-aggregated albumin scan by a larger center to provide a timely and important investigation in a logistically difficult scenario.

The Chemical Scaffold of Theranostic Radiopharmaceuticals: Radionuclide, Bifunctional Chelator, and Pharmacokinetics Modifying Linker

Therapeutic radiopharmaceuticals have been researched extensively in the last decade as a result of the growing research interest in personalized medicine to improve diagnostic accuracy and intensify intensive therapy while limiting side effects. Radiometal-based drugs are of substantial interest because of their greater versatility for clinical translation compared to non-metal radionuclides. This paper comprehensively discusses various components commonly used as chemical scaffolds to build radiopharmaceutical agents, i.e., radionuclides, pharmacokinetic-modifying linkers, and chelators, whose characteristics are explained and can be used as a guide for the researcher.

Diagnosis of Pulmonary Embolism on 99mTc-Labeled Macroaggregated Albumin Lung Imaging After Hepatic Arterial Injection for Planning of Radioembolization

ABSTRACT

A 54-year-old man with hepatocellular carcinoma from alcohol-induced cirrhosis presented with hepatic encephalopathy and refractory ascites related to decompensated liver disease. MRI confirmed disease progression adjacent the site of prior radiofrequency ablation, performed 2 years prior, with associated right hepatic vein tumor thrombus. 99mTc-labeled macroaggregated albumin lung shunt imaging performed before 90Y radioembolization identified a left lower lobe wedge-shaped defect, confirmed as pulmonary embolism on CT pulmonary angiography and MRI.

Freeze-dried microspheres for selective intra-arterial radionuclide therapy: an affordable solution

OBJECTIVE

Selective intra-arterial radionuclide therapy (SIRT) using radiolabelled microspheres is for the delivery of therapeutic radioisotope to liver cancers and thus, sparing healthy liver. Several radiolabelled microspheres are commercially available. The main issue associated with these microspheres is affordability. Re-188 is a generator produced radionuclide, emits high energy therapeutic beta particle and imageable gamma photons for pre- and post-therapy dosimetry.

METHODS

Tc-99m/Re-188 labelled microspheres have been developed and quality control tests have been performed for suitable clinical use. The clinical studies with Re-188 microspheres for SIRT have been performed. Post-therapy images were acquired for dosimetry.

RESULTS

The microspheres were found to possess spherical morphology of less than 20 µm size. The quality control revealed the suitability of microspheres for intravenous administration. The preliminary studies in thirty patients demonstrated good retention in tumor and high tumor to normal liver ratio. Re-188 microspheres were well tolerated by patients. Same microspheres labelled with either Tc-99m or Re-188 were used for pretherapy dosimetry and Re-188 labeled microspheres for therapy (SIRT) as a single-day procedure.

CONCLUSION

The freeze-dried microspheres may emerge as highly cost-effective candidates for both pre-therapy dosimetry and SIRT and may benefit a large population with inoperable liver cancer.

Complete Right-to-Left Shunt in Lung Perfusion Scintigraphy

ABSTRACT

Lung scintigraphy was performed to rule out pulmonary embolism in a 37-year-old woman suffering from dyspnea and hypoxemia after routine diagnostics failed to find the underlying disease. Perfusion scans did not show tracer uptake within the lungs despite ventilation scans being unremarkable. Instead, the result suggested a complete right-to-left shunt, which was a conundrum. With the assistance of CT an uncommon congenital vessel aberration turned out to be the cause of this exceptional scintigraphy finding, as well as the yet unexplained hypoxemia.

Pulmonary arteries: imaging of pulmonary embolism and beyond

The pulmonary arteries are not just affected by thrombus. Various acquired and congenital conditions can also affect the pulmonary arteries. In this review we discuss cross sectional imaging modalities utilized for the imaging of the pulmonary arteries. Acquired pulmonary artery entities, including pulmonary artery sarcoma (PAS), vasculitis, aneurysm, and arteriovenous malformations, and congenital anomalies in adults, including proximal interruption of the pulmonary artery, pulmonary sling, pulmonary artery stenosis, and idiopathic dilatation of the pulmonary trunk, are also discussed. An awareness of these entities and their imaging findings is important for radiologists interpreting chest imaging.

Platypnea-Orthodeoxia Syndrome: A Case of Chronic Paroxysmal Hypoxemia

A 75-year-old man with chronic (30-year) unexplained paroxysmal hypoxemia presented with postural hypoxemia and desaturation consistent with a clinical manifestation of platypnea-orthodeoxia syndrome. His history included a lack of significant past pulmonary disease, yet with intermittent need for oxygen supplementation. On admission he was found to have an interatrial shunt through a patent foramen ovale. Device closure by percutaneous catheterization led to sustained resolution of symptoms. Platypnea-orthodeoxia syndrome is a rare but important consideration in the differential diagnosis of hypoxemia, as it represents a potentially curable cause of hypoxemia, with missed diagnosis leading to possible patient morbidity if untreated. Even more importantly, an astute and careful history and physical examination are integral to the diagnosis of this rare but likely under-recognized syndrome.