Post-treatment Assessment of Glioblastoma Multiforme: Imaging with Fluorodeoxyglucose, Sestamibi, and Choline.

Glioblastoma multiforme (GBM) is the most common primary brain tumor in adults, and is generally of poor prognosis. The post-treatment assessment of GBMs is a known diagnostic issue, with problems in the differentiation of viable remnant tumor and post-treatment inflammatory changes. We present a case where various molecular tracers (fluorodeoxyglucose, choline, and methoxyisobutylisonitrile) were used in the post-treatment assessment of a patient with histologically proven GBM.

Imaging discordance between hepatic angiography versus Tc-99m-MAA SPECT/CT: a case series, technical discussion and clinical implications.

During pre-therapy evaluation for yttrium-90 (Y-90) radioembolization, it is uncommon to find severe imaging discordance between hepatic angiography versus technetium-99m-macroaggregated albumin (Tc-99m-MAA) single photon emission computed tomography with integrated low-dose CT (SPECT/CT). The reasons for severe imaging discordance are unclear, and literature is scarce. We describe 3 patients with severe imaging discordance, whereby tumor angiographic contrast hypervascularity was markedly mismatched to the corresponding Tc-99m-MAA SPECT/CT, and its clinical impact. The incidence of severe imaging discordance at our institution was 4% (3 of 74 cases). We postulate that imaging discordance could be due to a combination of 3 factors: (1) different injection rates between soluble contrast molecules versus Tc-99m-MAA; (2) different arterial flow hemodynamics between soluble contrast molecules versus Tc-99m-MAA; (3) eccentric release position of Tc-99m-MAA due to microcatheter tip location, inadvertently selecting non-target microparticle trajectories. Tc-99m-MAA SPECT/CT more accurately represents hepatic microparticle biodistribution than soluble contrast hepatic angiography and should be a key criterion in patient selection for Y-90 radioembolization. Tc-99m-MAA SPECT/CT provides more information than planar scintigraphy to guide radiation planning and clinical decision making. Severe imaging discordance at pre-therapy evaluation is ominous and should be followed up by changes to the final vascular approach during Y-90 radioembolization.

Clinical implications of the body surface area method versus partition model dosimetry for yttrium-90 radioembolization using resin microspheres: a technical review.

Yttrium-90 (Y-90) radioembolization is becoming established as an effective therapeutic modality for inoperable liver tumors. For resin microspheres, the 'body surface area (BSA)' method and the partition model can both be used for Y-90 activity calculation. The BSA method is semi-empirical, but more commonly used due its simplicity. The partition model is more accurate, scientifically sound and personalized, but less popular due to its complexity. This article provides a technical comparison of both methods with an emphasis on its clinical implications. Future dosimetric techniques for Y-90 radioembolization based on emerging technologies are also discussed.

Imaging of gastroenteropancreatic neuroendocrine tumors.

Imaging of gastroenteropancreatic neuroendocrine tumors can be broadly divided into anatomic and functional techniques. Anatomic imaging determines the local extent of the primary lesion, providing crucial information required for surgical planning. Functional imaging, not only determines the extent of metastatic disease spread, but also provides important information with regard to the biologic behavior of the tumor, allowing clinicians to decide on the most appropriate forms of treatment. We review the current literature on this subject, with emphasis on the strengths of each imaging modality.

Use of Ga-68 DOTATATE PET/CT to confirm portal vein tumor thrombosis in a patient with pancreatic neuroendocrine tumor.

A 37-year-old man complained of increasing severity and frequency of abdominal pain over a 2-year period. Initial contrast-enhanced computed tomography of the abdomen demonstrated diffuse enlargement of the pancreas associated with a filling defect in the portal vein, splenomegaly with wedge-shaped peripheral splenic hypodensities and multiple hepatic hypodensities. Findings were suggestive of a pancreatic malignancy complicated by hepatic metastases, splenic infarcts, and portal vein thrombosis. We describe the use of gallium-68 DOTA-DPhe1, Tyr3-octreotate positron emission tomography/computed tomography (Ga-68 DOTATATE PET/CT) in confirming the diagnosis of a pancreatic neuroendocrine tumor with portal vein tumor thrombosis.

Exploring new frontiers in molecular imaging: Emergence of Ga PET/CT.

Since US Food and Drug Administration approval of 18-fluorodeoxyglucose as a positron tracer, and the development of hybrid positron emission tomography/computed tomography machines, there has been a great increase in clinical application and progress in the field of nuclear molecular imaging. However, not underestimating the value of (18)F, there are known limitations in the use of this cyclotron-produced positron tracer. We hence turn our focus to an emerging positron tracer, (68)Ga, and examine the advantages, current clinical uses and potential future applications of this radioisotope.