Modified method for automatic exposure control in pediatric brain CT-application of the standard deviation value method by use of patient's age and head size.

We examined the optimum conditions for pediatric brain CT scans. CT controls the X-ray transit dose using tube current alteration called automatic exposure control (AEC) to adjust the standard deviation (SD) value for each scanning region, and it also reduces exposure. If the SD value is inappropriate, children may be exposed to increased radiation. Therefore we acquired images of 500 children from the server, and examined the most suitable SD value for each age using the data of their SD value and age. X-ray transit control with AEC was influenced by scan position and the age of a child. We enabled accurate scanning and decreased radiation exposure by adjusting AEC to the age and the cephalic volume of each child. As a result, reduction of the X-ray exposure by up to 31.2% per slice in tube current alteration was possible using a suitable SD value for each age. On the other hand, it was possible to reduce X-ray exposure by up to 67.9% per slice with the scan technique that used age and corrected cephalic volume without adjusting AEC. Using the tube current alteration protocol for each age with the data of the SD value or cephalic volume in CT, we can more easily conduct scans of children under optimal conditions.

An ex-situ arterial reconstruction for the treatment of an infected suprarenal abdominal aortic aneurysm involving visceral vessels.

A 66-year-old man, who had complaints of back pain, high fever, and constipation, with a suprarenal infected abdominal aortic aneurysm involving visceral vessels, was successfully treated by an ex situ arterial reconstruction. Blood culture revealed bacteroides melaninogenicus. After establishing a temporary bypass from right axillary to right external iliac artery, both renal arteries--superior mesenteric artery and common hepatic artery--were preliminary bypassed from external iliac arteries. Then aortic trunk reconstruction was performed with the body twisting left side to separate the graft from the infected field. The patient had good recovery and no evidence of recurrent infection 31 months after the operation.

Compression of the iliac vein by a synovial cyst.

While a synovial cyst of the hip is a rare cause of lower limb swelling, a differential diagnosis of deep vein thrombosis is needed. A case of lower limb swelling due to compression of the external iliac vein by a synovial cyst is presented with a review of the literature. Sagittal views and three-dimensional images of a CT scan were very useful for the diagnosis. This is the first review in English of vessel compression by a synovial cyst of the hip.

Ischemic preconditioning improves oxygenation of exercising muscle in vivo.

BACKGROUND: Ischemic preconditioning (IP) improves tissue tolerance to prolonged ischemia. In this study, we investigated the functional effect of IP on skeletal muscle of rat hind limb by means of near-infrared spectroscopy (NIRS) and by measuring myeloperoxidase (MPO) activity. MATERIALS AND METHODS: Adult male Sprague Dawley rats were divided into four separate protocol groups according to different preparations prior to 2 h of global ischemia: a group of ischemic reperfusion without any preparation (I/R), ischemic reperfusion with ischemic preconditioning (IP+IR), ischemic reperfusion with adenosine infusion (ADO+I/R), and sham operation. Ischemia and ischemic preconditioning were induced by clamping infrarenal abdominal aorta and left common iliac artery. For each rat, an exercise test of gastrocnemius muscles was performed by stimulating sciatic nerve before and after global ischemia while performing NIRS. MPO activity of ischemic muscles was also measured. RESULTS: Half-resaturation time after exercise and MPO activity were significantly improved in IP+IR and ADO+I/R groups. Difference of oxyhemoglobin during exercise was also improved in the IP+IR group. CONCLUSION: This study has demonstrated that IP provides the protective effect on in vivo skeletal muscle oxygenation during exercise.

AT-1015, a novel serotonin2A receptor antagonist, improves resaturation of exercised ischemic muscle in hypercholesterolemic rabbits.

OBJECTIVE: The effect of AT-1015, a serotonin(2A) receptor antagonist, on the resaturation of ischemic muscle in a hypercholesterolemic rabbit model was examined with near-infrared spectroscopy. METHODS: New Zealand White male rabbits were fed normal chow or cholesterol-rich chow. Ischemia was induced in the right hindlimb by ligation of the femoral artery, accompanied by balloon injury of the iliac artery. At 3 days after induction of ischemia, the bilateral gastrocnemius muscles were subjected to passive contraction for 2 minutes. The oxygen resaturation time of the gastrocnemius muscle after exercise was measured by near-infrared spectroscopy. AT-1015 was orally administered for 3 days after induction of ischemia. Assay of serotonin level in platelet-poor plasma and histologic examination of muscle and artery were performed in another set of rabbits. RESULTS: Oxygen resaturation time of the ischemic gastrocnemius was significantly prolonged in hypercholesterolemic rabbits compared with in normal rabbits without AT-1015, whereas there was no difference between both groups of rabbits that were administered AT-1015. Plasma level of serotonin in hypercholesterolemic rabbits was significantly increased compared with that in normal rabbits. No histologic differences were found in both muscle and artery among all groups. CONCLUSIONS: A serotonin(2A) receptor antagonist improved the oxygen resaturation of ischemic calf muscle after exercise in hypercholesterolemia. The interaction between plasma free serotonin and the serotonin(2A) receptor may play an important role in muscle oxygenation in ischemic limbs.

Differences in oxygen re-saturation of thigh and calf muscles after two treadmill stress tests.

Spatially resolved near-infrared oximeters quantify non-invasively muscle haemoglobin oxygen saturation (TOI) and, indirectly, local venous oxygen saturation (SvO(2)) and blood flow (MBF). TOI, SvO(2) and MBF of vastus lateralis and medial gastrocnemius were investigated after 5-min walking (3.2 km/h) and running (9.6 km/h) (n=7). The values of TOI were unchanged in the vastus lateralis during walking, whilst decreased during running in both muscles. For both muscles, TOI and SvO(2) values after walking were significantly greater than those found after running (P=0.043). The TOI went back (in 2 min) to its baseline value after walking in both muscles, whilst more slowly (in 4 min) after running in vastus lateralis. After running TOI of medial gastrocnemius had a tendency to be higher than the baseline value (reactive hyperaemia), concomitantly to the high MBF (twice the control value). The diverse oxygen demand in the stress tests and the consequent different pattern of TOI recovery reflect the different engagement of the two muscles. In conclusion, these results demonstrated the utility of TOI, independent of MBF and SvO(2), to be measured upon specific stress testing for differentiating the severity of peripheral vascular diseases and for assessing the collateral blood flow.