Densitometry for assessment of effect of lung volume reduction surgery for emphysema.

To explore if change in the extent of emphysema correlated with change in lung function, the effect of resection of emphysematous tissue was studied by computed tomography (CT) densitometry. In addition, the current authors studied how surgery-induced change in emphysema related to lung density in control subjects. In total, 30 patients (14 females; mean+/-sd age 59+/-10 yrs) with severe emphysema before and 3 months after lung volume reduction surgery (LVRS), 48 patients with moderate emphysema and 76 control subjects were investigated. Lung density (15th percentile point) of both lungs and heterogeneity of lung density between 12 isovolumetric partitions in each lung were calculated from chest CT images. The 15th percentile point and its heterogeneity could distinguish controls from subjects with moderate emphysema with a sensitivity and specificity of >95%. LVRS significantly increased lung density by 5.0+/-10.9 g.L(-1) (n=30). Improvement in the diffusing capacity of the lung for carbon monoxide and in residual volume significantly correlated with an increase in lung density (n=20 and 28, respectively). Change in forced expiratory volume in one second did not correlate with change in lung density. In conclusion, lung density 15th percentile point is a valuable surrogate marker for detection of both the extent of and reduction in emphysema.

[Diagnostic assessment of painless microhematuria: prospective study comparing image quality, assessibility and diagnostic certainty of multidetector-row CT and intravenous pyelography within a single examination]. / Diagnostische Abklärung der schmerzlosen Mikrohämaturie: Prospektive Studie zum Vergleich von Bildqualität, Beurteilbarkeit und diagnostischer Sicherheit von MDCT und IVU in einem Untersuchungsgang.

PURPOSE: The purpose of this study is to prospectively compare intravenous pyelography (IVP) and combined unenhanced and excretory phase multidetector-row CT (MDCT) with respect to image quality, diagnostic certainty and diagnostic concordance with the final clinical diagnosis in patients with painless microhematuria. MATERIALS AND METHODS: Unenhanced MDCT, IVP and excretory phase MDCT were performed in 59 consecutive patients (21 women, 38 men, mean age 56 +/- 19 years, range 23 - 83 years) with painless microhematuria of unknown origin during a single examination with a single contrast media application (100 ml, non-ionic iodinated contrast media). Images were assessed by two experienced urogenital radiologists in consensus for image quality, diagnostic certainty of stone detection, obstruction, parenchymal lesions and morphological distinctive features. Imaging diagnoses of MDCT and IVP were compared with the final clinical diagnoses. In case of failure to detect an relevant pathology, the final clinical diagnosis was established after a mean follow-up period of 18 +/- 6 months (10 months to 2 years). Costs and radiation exposure of IVP and MDCT were compared. RESULTS: MDCT scan performed better than IVP in terms of image quality for all regarded variables. Image quality of MDCT was rated in all parameters as very good or good; the image quality of IVP differed in a wide range. MDCT and IVP reached a sensitivity of 100 % and 50 % for stone detection (n = 14, p = 0.008), respectively. Two bladder stones were not detected by IVU but correctly seen with MDCT. MDCT and IVP were unsatisfactory for detecting transitional cell carcinomas (n = 4, 2 of 4 detected with MDCT, 0 of 4 detected with IVU). One false positive transitional cell carcinoma was detected with IVP, none with MDCT. Additional relevant pathological changes (one teratoma, one abdominal aortic aneurysma and one abscess) were detected using MDCT but missed with IVP. In 38 of 59 patients (64 %) imaging and clinical follow-up over up to 24 months did not reveal any pathology to explain the microhematuria. The costs of the IVP (283 Euro) were lower compared with non-enhanced MDCT (380 Euro) or combined non-enhanced and contrast-enhanced MDCT (560 Euro). The radiation exposure was 23 - 27 mSv for MDCT and 2.3 mSv for IVP. CONCLUSION: MDCT performed better regarding image quality, subjective diagnostic certainty and diagnostic results with respect to stone detection. Since urolithiasis is a frequent cause of painless microhematuria MDCT is recommended as the initial imaging modality rather than IVU.

Contrast optimization for assessment of the colonic wall and lumen in MR colonography.

This report focuses on the optimization of magnetic resonance colonography for combined virtual endoluminal and T2-weighted wall analysis of the colon and demonstrates the potential of the single-shot fast spin-echo (SSFSE) sequence for identifying colorectal pathologies. A 45 degrees flip angle in the three-dimensional spoiled gradient-echo sequence and a TE of 60 msec in the SSFSE sequence in conjunction with a 10 mM gadolinium concentration in the enema results in maximal contrast for the delineation of the colonic lumen in T1-weighted imaging and the colonic wall in T2-weighted imaging. The SSFSE sequence reveals hyperintense signal for inflammatory disease and most polyps exceeding 10 mm in size. It supplements the virtual endoluminal assessment by aiding in the differentiation between mass lesions and fecal matter or residual air.

CT angiography and Doppler sonography for emergency assessment in acute basilar artery ischemia.

BACKGROUND AND PURPOSE: Both Doppler sonography (DS) and spiral CT angiography (CTA) are noninvasive vascular assessment tools with a high potential for application in acute cerebral ischemia. The usefulness of CTA for vascular diagnosis in acute basilar artery (BA) ischemia has not yet been studied. METHODS: We prospectively studied 19 patients (mean+/-SD age, 58+/-11 years) with clinically suspected acute BA occlusion by DS and CTA. Prior extracranial and transcranial DS was performed in all but 1 patient, with DS 4 hours after CTA. In 6 of 19 patients, we performed digital subtraction angiography. RESULTS: CTA was diagnostic in all but 1 patient. CTA revealed complete BA occlusion in 9 patients and incomplete BA occlusion with some residual flow in 2 patients. A patent BA was shown in 7 patients. Because of severe BA calcification, CTA results were inconclusive in 1 patient. DS was diagnostic in only 7 of 19 patients, indicating certain BA occlusion in 3 patients and BA patency in 4 patients. In an additional 9 patients, the results of DS were inconclusive. DS was false-negative in 2 patients with distal BA occlusion shown by CTA and digital subtraction angiography. In 1 patient with DS performed after CTA, recanalization was demonstrated. In addition to the diagnosis or exclusion of BA occlusion, CTA provided information on the exact site and length of BA occlusion and collateral pathways. In our series, CTA results prompted indication for intra-arterial thrombolysis in 5 patients. CONCLUSIONS: CTA was superior to DS in the assessment of BA patency in patients with the syndrome of acute BA ischemia in terms of feasibility and conclusiveness, particularly in cases with distal BA occlusion. Our study confirmed the usefulness of combined extracranial and transcranial DS in the diagnosis and exclusion of proximal BA occlusion.

MR-guided percutaneous angioplasty: assessment of tracking safety, catheter handling and functionality.

PURPOSE: Magnetic resonance (MR)-guided percutaneous vascular interventions have evolved to a practical possibility with the advent of open-configuration MR systems and real-time tracking techniques. The purpose of this study was to assess an MR-tracking percutaneous transluminal angioplasty (PTA) catheter with regard to its safety profile and functionality. METHODS: Real-time, biplanar tracking of the PTA catheter was made possible by incorporating a small radiofrequency (RF) coil in the catheter tip and connecting it to a coaxial cable embedded in the catheter wall. To evaluate potentially hazardous thermal effects due to the incorporation of the coil, temperature measurements were performed within and around the coil under various scanning and tracking conditions at 1.5 Tesla (T). Catheter force transmission and balloon-burst pressure of the MR-tracking PTA catheter were compared with those of a standard PTA catheter. The dilatative capability of the angioplasty balloon was assessed in vitro as well as in vivo, in an isolated femoral artery segment in a swine. RESULTS: The degree of heating at the RF coil was directly proportional to the power of the RF pulses. Heating was negligible with MR tracking, conventional spin-echo and low-flip gradient-echo sequences. Sequences with higher duty cycles, such as fast spin echo, produced harmful heating effects. Force transmission of the MR-tracking PTA catheter was slightly inferior to that of the standard PTA catheter, while balloon-burst pressures were similar to those of conventional catheters. The MR-tracking PTA catheter functioned well both in vitro and in vivo. CONCLUSION: The in vivo use of an MR-tracking PTA catheter is safe under most scanning conditions.

Assessment of neuropsychological changes in patients with arteriovenous malformation (AVM) after radiosurgery.

PURPOSE: The purpose of this study was to investigate neuropsychological effects of radiosurgery in patients with cerebral arteriovenous malformation (AVM), with special focus on attention and memory. This report describes the study setup and presents the first results during a follow-up of up to 1 year. MATERIALS AND METHODS: Seventy-nine patients were studied before, acutely after radiosurgery, and during the regular follow-up (subacute phase: Weeks 6-12, chronic phase: Months 6-12). Radiosurgery was performed using a modified linear accelerator (minimum doses to the target volume: 15-22 Gy, median 20 Gy). Estimated whole brain dose was 0.5 to 2 Gy. Neuropsychological testing included assessment of general intelligence (Wechsler Adult Intelligence Scale), attention (modified Trail-Making Test A, Digit Symbol Test, D2 Test, Wiener Determination Machine) and memory (Rey Auditory Verbal Learning Test, Benton Visual Retention Test). During follow-up, alternate test versions were used. Neuropsychological deficits were defined as a test score of at least one standard deviation (SD) below the mean of the normal distribution. RESULTS: The pretherapeutic evaluation revealed marked deviations from the normal population; 24% had deficits in intelligence (range 23-31% in different subtests), attention (35%, 23-59%) and memory (48%, 31-61%). The overall percentage of aberrant results was reduced by 12% (memory) to 14% (attention) in the chronic phase up to 12 months after therapy. The improvement in test scores was significant (p < 0.05) in 3 of 4 subtests of attention functions. CONCLUSIONS: The acute tolerance of radiosurgery seems to be very good in these patients, showing no relevant increase in number of patients with neuropsychological deficits. Although the long-term follow-up needs to be further increased, our data indicate a tendency to slight improvement in the overall neuropsychological performance of AVM patients in the chronic phase after radiosurgery.

Lumbar spine: quantitative and qualitative assessment of positional (upright flexion and extension) MR imaging and myelography.

PURPOSE: To compare measurements of the sagittal diameter of the lumbar dural sac obtained at positional magnetic resonance (MR) imaging and at functional myelography and to assess the influence of various body positions on the dural sac and the intervertebral foramina. MATERIALS AND METHODS: Thirty consecutive patients referred for lumbar myelography were examined with an open 0.5-T MR imager, Sagittal T2-weighted fast spin-echo images were acquired with patients in the supine, upright flexion, and upright extension positions. The midsagittal diameter of the dural sac was measured at the level of the disks on MR images and myelograms. Foraminal sizes on the MR images were scored independently by two observers. RESULTS: Correlation between MR imaging and myelographic measurements was high (r = .81-.97). A small but statistically significant positional dependence of the dural sac diameter was found in the lower lumbar spine. Position-dependent differences in foraminal scores were uncommon. CONCLUSION: Quantitative assessment of sagittal dural sac diameters is comparable between lumbar myelography and positional MR imaging. In a selected patient population, only small changes in the sagittal diameter of the dural sac and foraminal size can be expected between various body positions, and the information gained in addition to that from standard MR imaging is limited [corrected].