Median-radial sensory nerve comparative studies in the detection of median neuropathy at the wrist in diabetic patients.

OBJECTIVE: Median-ulnar comparative studies (MUCS) play an important role in the electrodiagnosis of carpal tunnel syndrome, but in diabetes concomitant involvement of Guyon's canal (ulnar nerve compression at the wrist) would reduce the sensitivity of MUCS. This study tested the utility of median-radial comparative studies (MRCS) in diabetic patients. METHODS: Anti-dromic MUCS and MRCS were prospectively performed in 120 patients with diabetes, and 64 normal controls. In 28 diabetic patients, latent addition using threshold tracking was performed in superficial radial sensory axons to estimate persistent nodal sodium currents. RESULTS: MUCS was abnormal in 49% of the diabetic patients, and MRCS was abnormal in 58%. Median motor distal latencies were prolonged in 38%, and median sensory nerve conduction velocities were slowed in 40%. The longer latency differences in MRCS were associated with smaller persistent sodium currents, suggesting that intra-axonal sodium accumulation mediated by hyperglycemia enhances nerve compression. CONCLUSIONS: MRCS appears to be the most sensitive electrodiagnostic test in the detection of median neuropathy at the wrist in diabetic patients. Nerve conduction slowing across the carpal tunnel may be associated with metabolic abnormalities under hyperglycemia. SIGNIFICANCE: Assessment of nerve conduction across the common entrapment sites could provide new insights into the pathophysiology of diabetic neuropathy related to metabolic factors.

Abnormal collateral arterial systems in Takayasu's arteritis and Leriche's syndrome evaluated by whole body acquisition using multislice computed tomography.

Takayasu's arteritis causes various arterial changes, including wall thickening, occlusion, aneurysm, and calcification. Similarly, Leriche's syndrome causes occlusion of the abdominal aorta or iliac arteries accompanied by ischemic symptoms of the distal lower extremities. Both diseases are potentially associated with the development of unexpected collateral arteries throughout the body. We evaluated whole body arteries in subjects with Takayasu's arteritis and Leriche's syndrome using 16-slice multislice CT and concluded that it was a useful tool to detect unexpected collateral arterial systems in Takayasu's arteritis or Leriche's syndrome in a non-invasive fashion.

Utility of 256-slice cone beam tomography for real four-dimensional volumetric analysis without electrocardiogram gated acquisition.

PURPOSE: Current ECG-gated multislice CT can reveal any cardiac phase data, including four-dimensional (4D) images, but cannot acquire the whole heart in one scanning, and arrhythmias impair the quality of the images. We used a prototype 256-slice cone beam CT (Athena, Sony Toshiba), with which the whole heart can be acquired in one scanning. MATERIALS AND METHODS: A pulsating device with contrast material (300 mgI/dl) diluted 10x with saline was moved at 5, 40, 60, 70, and 90 to-and-fro movements/min. Non-ECG-gated 256-slice cone beam CT with 256 x 0.5 mm slice thickness was performed during one to-and-fro motion at each rate. After acquisition, each to-and-fro motion was divided into 20 frames, and each volume was measured and volumetric curves were constructed. RESULTS: Even without ECG-gated acquisition, the configuration of the pulsating device at any rate continued to the through plane without any gaps, and the 4D movie of the pulsating device could be observed at any rate except 60 movements/min. Volumes of end-diastole (ED) and end-systole (ES), and ejection fraction (EF) at static state were 81.7, 17.5 ml, and 79% respectively. ED volumes were 81.7, 81.7, 70.3, 63.7, 68.3 and 65.9 ml, ES volumes were 17.5, 30.9, 39.8, 62.7, 55.0 and 43.2 ml, and EF was 79, 62, 43, 2, 19 and 34% at 0, 5, 40, 60, 70, and 90 to-and-fro movements/min, respectively. The ratios of ED volume, using the static state as the reference, were 100, 86, 78, 84 and 81%, those of ES volume were 177, 227, 358, 314 and 247%, and those of EF were 78, 54, 3, 24 and 43% at 5, 40, 60, 70, and 90 to-and-fro movements/min, respectively. From the configuration of volumetric curves, only 5/min could be evaluated. At 60 movements/min, the same device images without any motion were observed in 4D images during one to-and-fro motion. This may be because one to-and-fro time and one scanning time were the same (1 s). CONCLUSION: Even without ECG-gated acquisition, this new 256-slice cone beam CT achieved real 4D analysis of the pulsating device. The ED volume and the configuration of volumetric curve could only be evaluated up to 5 movements/min, but because of poor spatial resolution (1 s/rotation), even at 5 movements/min ES volume tended to be overestimated. As a result, EF tended to be underestimated, which may be improved in the next generation (0.5 s/rotation).

Anatomical remodeling of left atria in subjects with chronic and paroxysmal atrial fibrillation evaluated by multislice computed tomography.

PURPOSE: We used ECG-gated enhance multislice computed tomography (MSCT) to evaluate and compare anatomical change to left atria (LA) including left atrial appendage (LAA) in subjects with chronic and paroxysmal atrial fibrillation (CAF and PAF, respectively). MATERIALS AND METHODS: Retrospective ECG-gated MSCT (Light Speed Ultra 16, General Electric) was performed in 16 subjects with CAF (10 male, median age 68/period of CAF 6 years, 3 severe or moderate mitral stenosis (MS), 3 mitral regurgitation (MR)) and 17 with PAF (11 male, median age 62/period of PAF 3 years, one MS, one MR) 30 s and 8 min after injection of contrast. We evaluated: qualified observed morphology of pectinate muscles (PM) in LAA (well/poorly/non-developed); absolute thickness of LA anterior wall; presence of abnormal late enhancement (LE) of LA wall suggesting fibrotic changes; defect of contrast in LAA only in early phase and LAA enlargement; comparison of LA diameter evaluated by 4-chamber view obtained by transthoracic echocardiogram. RESULTS: CAF group: well-developed PM (19% subjects), poor PM (43%), no PM (38%). PAF group: well-developed PM (41%), poor PM (47%), no PM (12%). Incidences of well- and non-developed PM were significantly less and more in CAF group, respectively. CAF subjects with no PM had longer periods of CAF and larger LA diameter than those with developed PM (p<0.01). By contrast, there was no relation between PM morphology and PAF periods or LA diameter. Incidence and mean thickness of abnormal LE of LA wall were similar in both groups (2.6 mm): 25% (CAF); 24% (PAF). There was a negative correlation in the CAF group between thickness of LA wall and LA diameter (R2=0.19), but not in the PAF group. Contrast defect in LAA only in early phase and enlargement of LAA were observed in 56%, 88% (CAF) and 24%, 41% (PAF); ratios were significantly higher in CAF group (p<0.01). CONCLUSIONS: There were anatomical differences between CAF and PAF groups in MSCT. In CAF group, depending on the period of CAF or degree of LA diameter enlargement, anatomical remodeling (e.g. recession of PM, thinning of LA wall, enlargement of LAA) may appear, which may cause blood flow stagnation, seen as contrast defect in LAA in early phase.

Epidemiology of fat replacement of the right ventricular myocardium determined by multislice computed tomography using a logistic regression model.

PURPOSE: We frequently observe fat replacement (FR) of the anterior wall of the right ventricular myocardium (RVM), but its epidemiological significance is not clear. METHODS AND MATERIALS: 49 consecutive subjects (28 males, 36-83 years old, median 67) underwent enhanced ECG-gated multislice CT (Light speed ultra 16, General Electrics, WI) and we retrospectively analyzed the presence of FR of RVM. A logistic model for predicting FR of RVM was constructed using age, sex, hypertension [HT], diabetes mellitus [DM], hyperlipidemia [HL] smoking, obesity (body mass index >25.0) and calcified and non-calcified plaques of coronary arteries (CA). RESULTS: FR of RVM was detected in 21 subjects (12 males, 51-78 years old, median 67), 76% of whom had HT, 38% DM, 43% HL, 48% smoking history, 52% were obese, and 76% had calcified and 24% had non-calcified plaques of CA. Only obesity was significantly higher in FR (p<0.05). A logistic regression model showed, although there was a close association between obesity and an increased incidence of FR, it did not reach statistical significance (p=0.0515, relative risk 5.11). CONCLUSIONS: Obesity is significantly more common in cases of FR, and despite a negative multivariable analysis, may influence FR in the RVM. FR in obesity may occur independently of clinically-significant arrhythmia, which is different from ARVC. Thus, even with FR, obesity must be considered as a diagnosis before ARVC.