Impact of time-of-flight on qualitative and quantitative analyses of myocardial perfusion PET studies using (13)N-ammonia.

BACKGROUND: The impact of time-of-flight (TOF) in myocardial perfusion (13)N-ammonia positron emission tomography (PET) is unclear. METHODS AND RESULTS: Twenty consecutive subjects underwent rest and adenosine stress (13)N-ammonia myocardial perfusion PET. Two sets of images were reconstructed using TOF-ordered subset expectation maximization (TOF-OSEM) and 3-dimensional row-action maximum likelihood algorithm (3D-RAMLA). Qualitative and quantitative analyses from the TOF-OSEM and 3D-RAMLA reconstructions were compared. Count profile curves revealed that TOF relatively increased the uptake of (13)N-ammonia at the lateral walls, and apical thinning was emphasized on the TOF images. Both segmental rest and stress myocardial blood flow (MBF) values were higher with TOF-OSEM use than with 3D-RAMLA use (rest MBF: 0.955 ± 0.201 vs 0.836 ± 0.185, P < .001; stress MBF: 2.149 ± 0.697 vs 2.058 ± 0.721, P < .001). The differentiation of MBF between reconstructions was more enhanced under rest conditions. Thus, segmental myocardial flow reserve (MFR) observed using TOF-OSEM reconstruction was lower than that observed using 3D-RAMLA (2.25 ± 0.57 vs 2.46 ± 0.75, P < .001). No remarkable differences were observed between segmental and territorial results. CONCLUSIONS: TOF increased lateral wall counts and emphasized apical thinning. Quantitatively, TOF reconstruction showed increased MBF, especially under relatively low perfusion conditions.

Estimation of Microvascular Dysfunction by Using 13N-Ammonia Positron Emission Tomography with Quantitative Myocardial Blood Flow Analysis in Chronic Coronary Syndrome.

BACKGROUND: Although coronary artery disease (CAD) is characterized by epicardial atherosclerosis and microvascular disease, the importance of evaluating microvascular dysfunction has not been sufficiently recognized in clinical practice. We estimated microvascular disease severity by assessing hyperemic microvascular resistance (MVR), as determined by absolute quantification of myocardial blood flow (MBF) with 13N-ammonia positron emission tomography-myocardial perfusion imaging (PET-MPI). METHODS: We retrospectively collected data for 23 CAD patients who underwent both stress/rest PET-MPI and invasive coronary angiography (CAG) with fractional flow reserve (FFR) measurement. Among 30 vessels for which FFR measurement was performed, 13 had a low FFR (FFR ≤0.75). For each patient, myocardial segments of a standard 17-segment model were assigned to the stenotic myocardial area perfused by the FFR-measured vessel and a reference normal-perfusion area based on PET-MPI and the coronary distribution on CAG. Hyperemic MVR was calculated by using the formula, hyperemic MVR = hyperemic mean blood pressure × FFR/hyperemic MBF of the stenotic vessel. RESULTS: A strong negative correlation was observed between hyperemic MVR and hyperemic MBF in the reference normal-perfusion area (R = -0.758, P<0.001). CONCLUSION: Microvascular disease severity in chronic CAD can be estimated by hyperemic MBF of the normal-perfusion area with 13N-ammonia PET-MPI.

Treatment of pulmonary thromboembolism with edoxaban in a cancer patient with borderline fulfillment of the dose reduction criteria.

Venous thromboembolism is the most common cause of death in cancer patients with venous thrombosis. Treatment of venous thrombosis is important in cancer patients, as it can have a major impact on prognosis. We report a case of advanced gastric cancer that was discovered owing to pulmonary thromboembolism and describe the treatment for both conditions. Dose reduction criteria of edoxaban are established. Appropriate dose was based on body weight and creatinine clearance; patients with creatinine clearance values slightly exceeding or below 50 are considered to be on the borderline of the dose reduction criteria. This case had borderline value (body weight: 63 kg, creatinine clearance: 46 mL/min). We observed no response after initiating treatment with 30 mg edoxaban; however, pulmonary thrombus disappeared after increasing the dose to 60 mg edoxaban. When selecting an anticoagulation drug in borderline patients with cancer-associated thrombosis, dose increase should be considered if hemorrhage risk is assessed.

Gastrointestinal fiberscopic findings after simple closure for perforated duodenal ulcer in the early postoperative phase: from experience to evidence by evaluation of the healing process.

BACKGROUND/AIMS: Today, in light of widespread adoption of H2-RA and PPI, the standard surgical procedure for perforated duodenal ulcer (PDU) is simple closure and/or omental patch (SC). However, the healing process after these techniques has not been fully examined. We have not yet confirmed the propriety of simple suture of the bottom of the ulcer. This technique has been performed based only on experience, and there is insufficient evidence to conclude that this procedure can be definitively considered a safe therapeutic technique for the majority of patients with PDU. The aim of this study is to clarify the macroscopic findings of the healing process after SC for PDU. METHODOLOGY: Thirteen patients with PDU who were treated with SC underwent postoperative gastroduodenal fiberscopy (GF) at the 7th-16th postoperative day and the healing process was monitored under sufficient informed consent. Patients with severe preoperative disease were excluded from the study. Healing condition of the ulcer and stitches, deformity, and stenosis were evaluated by postoperative endoscopy. Possible adverse effects that were evaluated included: perforation, rise in fever, worsening of inflammation on laboratory data, gastrointestinal symptoms such as abdominal pain, sense of fullness, and vomiting. The indications for SC were as follows: PDU with 1) no stenosis and 2) no prominent ulcer ridge. The surgical technique was as follows: 1) interrupted simple closure with no trimming and debridement of wound (4-5 stitches) with absorbable monofilament suture, and/or 2) omental patch, 3) administration of H2-RA (or PPI) just after operation, and 4) oral feeding 4-5 days after operation independent of postoperative GF. RESULTS: GF findings in 2 patients showed active and healing stage, in whom surgical technique was thought to be insufficient; the ulcer had been large and included a descending portion, or a small perforation had occurred in the large ulcer bottom (the distance between the stitches and the edge of the ulcer was insufficient). In the other 11 patients, GF findings showed scar phase. There was no morbidity related to endoscopic procedure. CONCLUSIONS: Sutured PDU with SC will be in the scar phase in 1 or 2 weeks. Postoperative GF 1 week after SC for PDU is thought to be a safe examination. This study is a primitive study of a small group, and more cases that can adequately show the frequency of complications and indicate the overall safety of the procedure are needed.

Oxygen metabolism of the liver during an HA clamp: HV saturation and free radicals.

BACKGROUND/AIMS: To clarify changes in the hepatic oxygen metabolism and tissue damage resulting from oxygen-derived free radical generation from polymorphonuclear cells during a hepatic arterial clamp. METHODOLOGY: Subjects were 32 male Wistar rats. Hepatic tissue blood flow, and hepatic venous chemiluminescence, indicating oxygen-derived free radicals from polymorphonuclear cells, and liver lipid peroxide were measured, and hepatic and portal venous blood gas analysis were performed before and after 130 minutes of hepatic arterial clamping. RESULTS: Hepatic tissue blood flow decreased by hepatic arterial clamp. The values of hepatic arterial oxygen pressure (HTBF), hepatic venous oxygen saturation (ShvO2), and O2 contents after hepatic arterial clamp were lower than those before hepatic arterial clamp (P = 0.035, 0.024, and 0.028, respectively). Hepatic venous chemiluminescence decreased and the lipid peroxide level of the liver increased by hepatic arterial clamp (P = 0.001). CONCLUSIONS: ShvO2 is useful for the evaluation of hepatic oxygen metabolism and hepatic tissue blood flow during acute hepatic arterial clamp. This condition should prepare the following tissue damage due to oxygen-derived free radicals from polymorphonuclear cells.

Gastric emptying of a carbohydrate-electrolyte solution in healthy volunteers depends on osmotically active particles.

BACKGROUND: Preoperative ingestion of only clear fluids until 2 hours before induction of anesthesia is a common preoperative fasting regimen. Gastric emptying times, however, vary among clear fluids. We therefore investigated the gastric emptying of 2 clear glucose-electrolyte drinks. METHOD: A 2-way crossover study was performed in 10 healthy volunteers. After fasting, the volunteers drank 500 mL of either OS-1(®), an oral rehydration solution, or Pocari Sweat(®), a popular sports drink, over 3 minutes in a standing position. Magnetic resonance imaging was performed before, immediately after, and 30 minutes after the drinking of each test fluid. The difference in gastric emptying between OS-1(®) and Pocari Sweat(®) was evaluated by comparing gastric fluid volume, flow rate, and residual ratio. We also compared the flow rates of sodium, potassium, carbohydrates, and osmotically active particles in the 2 test fluids. RESULTS: Gastric fluid volume 30 minutes after drinking was significantly smaller for OS-1(®) (76.0 ± 57.0 mL) than for Pocari Sweat(®) (158.1 ± 73.5 mL, p<0.01), although the volumes did not differ before or immediately after drinking. The flow rate was significantly faster for OS-1(®) (10.66 ± 3.34 mL) than for Pocari Sweat(®) (8.68 ± 3.02 mL/min, p<0.05), and the residual ratio was significantly smaller for OS-1(®) (21 ± 14% than for Pocari Sweat(®) (41 ± 19%, p<0.01). The flow rates of sodium, potassium, and glucose differed significantly between OS-1(®) and Pocari Sweat(®), whereas the flow rate of osmotically active particles did not. CONCLUSIONS: Gastric emptying is significantly faster for OS-1(®) than for Pocari Sweat(®).