Proton MR spectroscopy of tumefactive demyelinating lesions

BACKGROUND AND PURPOSE: Tumefactive demyelinating lesions (TDLs) can simulate intracranial neoplasms in clinical presentation and MR imaging appearance, and surgical biopsy is often performed in suspected tumors. Proton MR spectroscopy has been applied in assessing various intracranial diseases and is increasingly used in diagnosis and clinical management. Our purpose was to determine if multivoxel proton MR spectroscopy can be used to differentiate TDLs and high-grade gliomas. METHODS: Conventional MR images, proton MR spectra, and medical records were retrospectively reviewed in six patients with TDLs diagnosed by means of biopsy or by documented clinical improvement, with or without supporting laboratory testing and follow-up imaging. Proton MR spectra of 10 high-grade gliomas with similar conventional MR imaging appearances were used for comparison. In contrast-enhancing, central, and perilesional areas of each lesion, peak heights of N-acetylaspartate (NAA), choline (Cho), and creatine (Cr) were measured and the lactate peak noted. Cho/Cr and NAA/Cr ratios of corresponding regions in TDLs and gliomas were compared. RESULTS: No significant differences in mean Cho/Cr ratios were found in the corresponding contrast-enhancing, central, or perilesional areas of TDLs and gliomas. The mean central-region NAA/Cr ratio in gliomas was significantly lower than that of TDLs, but mean NAA/Cr ratios in other regions were not significantly different. A lactate peak was identified in four of six TDLs and three of 10 gliomas. CONCLUSION: In the cases examined, the NAA/Cr ratio in the central region of TDLs and high-grade gliomas differed significantly. However, overall metabolite profiles of both lesions were similar; this finding emphasizes the need for the cautious interpretation of spectroscopic findings.     

Captopril mediated decrease of aortic regurgitation.

The effect of captopril mediated afterload reduction on aortic regurgitation was investigated in 10 patients. Regurgitation was quantitated by means of the regurgitation fraction and the relation of regurgitant volume to end diastolic volume. These variables were derived from gated radionuclide ventriculography. After captopril treatment the blood concentration of angiotensin I rose whereas that of angiotensin II fell significantly. The conversion of angiotensin I to II was reduced to about 50% of the control value. Whereas blood pressure and heart rate did not change significantly, the regurgitation fraction and the regurgitant volume, normalised to end diastolic volume, were significantly reduced by captopril treatment. The ejection fraction remained essentially unchanged. These findings suggest that captopril reduces aortic regurgitation by reducing afterload.     

Tarsal navicular stress fractures: radiographic evaluation

Tarsal navicular stress fractures are a potential source of disabling foot pain in physically active individuals. The diagnosis of tarsal navicular stress fracture requires a high index of clinical and radiographic suspicion because the fracture is only rarely evident on routine radiographs or standard tomograms. The radiographic diagnosis of a tarsal navicular stress fracture may require anatomic anteroposterior tomograms or a radionuclide bone scan with plantar views. Radiographic examinations of 23 fractures in 21 patients are evaluated.     

Preservation of olfaction in bifrontal craniotomies for lesions of the anterior and middle cranial fossa

OBJECTIVE: The preservation of the olfactory tract during bifrontal approach for lesions located in the frontal skull base and the supra- and parasellar region has not previously been investigated. METHODS: In our study 12 patients underwent surgery for various lesions via the basal subfrontal route. All patients were observed prospectively, olfaction testing was performed pre- and postoperatively by an independent otorhinolaryngologist. RESULTS: We obtained complete preservation of the olfactory tracts and normal postoperative olfaction in all 12 cases. CONCLUSION: The bifrontal approach allowed a bilateral, wide operative field with excellent orientation and views of important structures. The shortcoming of this method, damage of the olfactory tracts and postoperative anosmia can be overcome.     

Impact of intra-abdominal fat and age on insulin sensitivity and beta-cell function

The prevalence of glucose intolerance and type 2 diabetes increases with age. To determine whether the hyperbolic relationship between insulin sensitivity and the insulin response is affected by age and whether the decline in beta-cell function with age is related to increases in intra-abdominal fat or age per se, we studied 220 healthy subjects with fasting glucose <6.1 mmol/l (89 men and 131 women, aged 26-75 years, BMI 18.7-40.4 kg/m(2)). The insulin sensitivity index (S(i)) and the acute insulin response to glucose (AIRg) were determined, and from these beta-cell function was estimated as the disposition index (S(i) x AIRg). Intra-abdominal fat and subcutaneous fat areas were quantified by computed tomography. S(i) (5.40 +/- 0.5 vs. 7.86 +/- 0.7 x10(-5) min(-1)/[pmol/l]), P < 0.01) was decreased and intra-abdominal fat (117 +/- 10 vs. 81 +/- 9 cm(2), P < 0.05) was increased in the oldest (age 60-75 years) versus the youngest (age 26-44 years) quartile. The hyperbolic relationship between S(i) and AIRg was present independent of age; thus, beta-cell function measured as the disposition index (1,412 +/- 120 vs. 2,125 +/- 150 x10(-5) min(-1), P < 0.01) was lower in the oldest versus the youngest quartile. In multiple regression, intra-abdominal fat (r = -0.470, P < 0.001) but not age was associated with S(i), but both intra-abdominal fat (r = -0.198, P = 0.003) and age (r = -0.131, P = 0.05) were correlated with the disposition index. These data suggest that although intra-abdominal fat is a strong determinant of insulin sensitivity and beta-cell function, age has an independent effect on beta-cell function that may contribute to the increased prevalence of type 2 diabetes in older populations.