Kasper Pedersen

FDG-PET/CT in Infectious and Inflammatory Diseases

Nuclear medicine techniques have been an integral part of infection and inflammation imaging for decades; in recent years, fluorodeoxyglucose-positron emission tomography/computed tomography (FDG-PET/CT) has taken over many indications. This review provides a comprehensive overview of the current and potential applications for FDG-PET/CT in infectious and inflammatory diseases (ie, systemic infections, bone infections, vascular infection and inflammation, thoracic and abdominal inflammation) and potential novel applications in both infection and inflammation.

Synthesis and cerebral uptake of 1-(1-[(11)C]methyl-1H-pyrrol-2-yl)-2-phenyl-2-(1-pyrrolidinyl)ethanone, a novel tracer for positron emission tomography studies of monoamine oxidase type A

( R)-(-)- and ( S)-(+)-1-(1-[ (11)C]methyl-1 H-pyrrol-2-yl)-2-phenyl-2-(1-pyrrolidinyl)ethanone 4 and 5 were synthesized, and their properties as tracers for positron emission tomography (PET) studies of monoamine oxidase type A (MAO-A) in the brain of living pigs were tested. Parametric maps of the distribution volume ( V d) 4 in pig brain were qualitatively similar to those obtained with [ (11)C]harmine, with prominent binding in the ventral forebrain and mesencephalon. Its binding was highly vulnerable to MAO blockade, suggesting a binding potential as high as 2 for MAO-A sites. The slow plasma metabolism of 4 and 5 may present advantages over [ (11)C]harmine for routine PET studies of MAO-A.

15-O-water myocardial flow reserve PET and CT angiography by full hybrid PET/CT as a potential alternative to invasive angiography

Combined myocardial flow reserve (MFR) by PET and CT coronary angiography (CTA) is a promising tool for assessment of coronary artery disease. Prior analyses of MFR/CTA has been performed as side-by-side interpretation, not as volume rendered, full hybrid analysis, with fused MFR/CTA. We aimed to: (i) establish a method for full hybrid analysis of MFR/CTA, (ii) validate the inter- and intra-observer reproducibility of MFR values, and (iii) determine the diagnostic value of side-by-side versus full hybrid MFR/CTA with 15-O-water PET. Forty-four outpatients scheduled for invasive coronary angiography (ICA) were enrolled prospectively. All underwent rest/stress 15-O-water PET/CTA with ICA as reference. Within two observers of different experience, the Pearson r at global and territorial level exceeded 0.953 for rest, stress, and MFR values, as determined by Carimas software. Within and between observers, the mean differences between rest, stress, and MFR values were close to zero and the confidence intervals for 95% limits of agreement were narrow. The diagnostic performance of full hybrid PET/CTA did not outperform the side-by-side approach, but performed better than MFR without CTA at vessel level: specificity 93% (95% confidence limits: 89–97%) versus 76% (64–88%), p = 0.0004; positive predictive value 71% (55–86%) versus 51% (37–65%), p = 0.0001; accuracy 90% (84–95%) versus 77% (69–84%), p = 0.0009. MFR showed high reproducibility within and between observers of different experience. The full hybrid model was not superior to side-by-side interpretation of MFR/CTA, but proved better than MFR alone at vessel level with regard to specificity, positive predictive value, and accuracy.

Somatostatin receptor imaging may establish the neuroendocrine nature of unclarified metastases

Traditionally, functional imaging with somatostatin receptor analogues is used in the primary diagnostics, staging, and monitoring of neuroendocrine tumors (NETs) as well as to asses the potential effect of treatment with (radioactive) somatostatin analogues. We report a case in which a woman was diagnosed with a low grade NET in a liver biopsy, but results from the diagnostic work-up pointed towards a synchronous, high grade, metastasizing malignancy. Because of the patient’s poor general health, invasive procedures were deemed unattainable. Somatostatin receptor scintigraphy with the tracer 111 In-pentetreotide was therefore used as a very specific method of establishing the neuroendocrine nature of all the lesions found, and hence, palliative treatment could be commenced. This case thereby illustrates the feasibility of using somatostatin receptor imaging to establish the neuroendocrine nature of metastases suspected of originating from a synchronous high grade malignancy, when a low grade neuroendocrine tumor has been diagnosed elsewhere and invasive procedures are not possible.