The Role of SPECT/CT in Peritoneal Scintigraphy in the Era of Low-Dose Imaging: A Case Report.

Peritoneal scintigraphy, although rarely used, plays a vital role in the diagnosis of peritoneal dialysis catheter complications. Reported complications include spontaneous hydrothorax secondary to a pleuroperitoneal fistula, which requires the abandonment of peritoneal dialysis, given that a delay in diagnosis can lead to worsening clinical status. Previously reported peritoneal scintigraphy protocols recommended intraperitoneal instillation of radiotracer and moderate-to-large volumes of dialysate or sterile saline ranging from 350 to 2,000 mL. However, smaller volumes, in conjunction with the use of single-photon emission computed tomography/computed tomography, are not verified in patients receiving peritoneal scintigraphy imaging.

Rare presentation of inflammatory pseudotumour involving subcutaneous tissues with superficial fat sparing.

We present a unique case of inflammatory pseudotumour involving gluteal subcutaneous tissue with the sparing of superficial fat and report its contrast-enhanced CT, F-18 fluorodeoxyglucose positron emission tomography/CT and pathological findings. Although rare, inflammatory pseudotumours have been reported with a diverse spectrum of locations; however, the involvement of the subcutaneous tissue overlying the gluteal muscles with sparing of the most superficial fat has not been reported.

Graft-Versus-Host Disease Presenting as a Myositis and Myonecrosis.

Graft-versus-host disease (GVHD) is a major complication of bone marrow transplantation. Polymyositis with myonecrosis is a rare manifestation of GVHD. Here, we report the case of a 32-year-old man with acute myeloid leukemia who developed GVHD after transplant. He subsequently developed polymyositis, which was diagnosed on PET/CT and confirmed on pathology. Treatment with corticosteroids resulted in the resolution of the symptoms. Abnormal muscular FDG uptake resolved on the follow-up PET/CT.

Tandem mass spectrometry and density functional theory of RDX fragmentation pathways: Role of ion-molecule complexes in loss of NO3 and lack of molecular ion peak.

RATIONALE: Hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) is an explosive compound that finds a wide range of military and civilian applications. RDX has been a target in environmental matrices by gas chromatography/tandem mass spectrometry (GC/MS/MS). MS/MS in negative chemical ionization (NCI) mode of RDX provides important fragmentation patterns that are useful for structural elucidation. The fragmentation patterns are needed for proper identification of precursor and product ions in analytical methods that depend on MS/MS approaches for a reliable identification of RDX. METHODS: This study focuses on the MS fragmentation mechanisms of RDX in NCI mode using both MS/MS and density functional theory (DFT). The DFT studies were performed at the B3LYP/6-311G(d,p) level of theory. RESULTS: The DFT results showed that NCI of RDX leads to the formation of an anion-molecule complex that was energetically more stable than the RDX anion. The fragmentation proceeds through two pathways, leading to the loss of NO(2) and NO(3). The loss of NO(3) takes place in an anion-molecule complex leading to the formation of characteristic nitroso group fragment ions. Using the fragmentation schemes, important ion structures are proposed including structures for m/z 160, 129, 102, and 86. CONCLUSIONS: The results demonstrate the importance of both charge-induced and charge-remote dissociations in RDX pathways. The ion structures identified along the pathways could be used as targets in analytical methods for reliable identification purposes.

Mammographic detection of breast arterial calcification as an independent predictor of coronary atherosclerotic disease in a single ethnic cohort of African American women.

OBJECTIVE: Accumulating data on predominantly Caucasian women suggests an association between breast arterial calcification (BAC) and coronary artery disease (CAD). We sought to comprehensively examine the correlation between mammographic BAC and CAD endpoints detected by cardiac computed tomography (CCT) in African American (AA) women. METHODS: Consecutive AA women who underwent digital screening mammography and CCT were identified. In blinded fashion, mammographic and CCT studies were reviewed. Patient-related pertinent covariates were assessed. RESULTS: Two-hundred-four AA women (median age, 52.5 years) were included. BAC was present in 42 women (20.6%). BAC was significantly associated with coronary artery calcium score >100 (odds ratio [OR], 7.66; 95% confidence interval [CI], 2.75-21.29; P < 0.001), atherosclerotic luminal narrowing (OR, 9.99; CI, 3.65-27.32; P < 0.001), and stenosis ≥50% (OR, 5.48; CI, 1.97-15.23; P = 0.001) by CCT. CONCLUSION: In AA women, BAC is associated with increased probability of coronary calcification, atherosclerosis, and CAD on CCT.

Free radical routes for prebiotic formation of DNA nucleobases from formamide.

Modeling the complicated chemical reactions in the interstellar medium and surface materials of Titan is nontrivial. Since both the atmosphere and the surface are rich in organic molecules, the chemistry may have important implications for the origin of biomolecules. Prebiotic synthesis of DNA nucleobases from simple molecules such as formamide has been known for more than half a century. In this study, new free radical pathways leading to the synthesis of guanine, hypoxanthine, purine, and adenine have been studied using density functional theory (B3LYP with the 6-311G(d,p) basis set). The pathways of the selected nucleobases demonstrate the importance of free radicals in the production of useful biomolecules under conditions appropriate for the interstellar medium or on Titan. The pathways may be universal in nature and proceed without solvent requirements. Calculations indicate that radical pathways yield lower reaction barriers as compared to previously reported pathways. Overall, these results suggest that the chemistry on Titan's surface and/or the growth of organic particulates in the haze layers in Titan's atmosphere likely involve free radicals. The mechanisms demonstrate that important prebiotic precursors can be predicted. The reaction sequences reported here may lead to the production and build-up of molecules with prebiotic relevance.