Dynamic MRI has proven to be an important tool in studies of transient physiologic changes in animals and humans. High sensitivity and temporal resolution in such measurements are critical for accurate estimation of dynamic information. Fast imaging, often involving expensive hardware, has evolved for use in such cases. We demonstrate herein the possibility of accelerated data acquisition schemes on conventional machines using standard pulse sequences for dynamic studies. This is achieved by combining reduced-encoded dynamic data (typically 30 to 40 phase encodings) with a priori high-resolution data via a novel constrained image reconstruction algorithm. Such an approach reduces image acquisition time significantly (by a factor of 3 to 4 in the examples described here) without loss in the accuracy of information.

Animals↗

PubMedDate not supplied

Epidemic dengue transmission in southern Sumatra, Indonesia.

An outbreak of dengue fever (DF), dengue haemorrhagic fever (DHF), and dengue shock syndrome (DSS) in the city of Palembang, south Sumatra, Indonesia was investigated to (i) validate epidemic occurrence, (ii) confirm dengue virus aetiology and associated serotype(s), (iii) provide a demonstrable measure of community impact, and (iv) identify causative relationship (if any) with climatic El Niño Southern Oscillation (ENSO) influences. Trend analysis based on a 6-year retrospective review of hospital records demonstrates a 3-fold increase in clinical cases for the outbreak period (January-April 1998), relative to historical records. In the 2 hospitals surveyed, the monthly mean number of outbreak-related dengue cases over 4 months was 833 (range 650-995 cases/month); the mean monthly value for the previous 72 months was 107 (range 14-779 cases/month). An apparent trend in epidemic transmission was observed, evolving from a 5-year cyclic phenomenon to an annual occurrence, often indistinguishable from one year to the next. The proportional distribution of clinical outbreak cases into DF, DHF and DSS diagnostic categories was 24%, 66%, and 10%, respectively. The population aged 10-19 years accounted for the largest (35%) proportion of hospitalized DHF cases, followed by children aged 5-9 years (25%) and children aged 4 years (16%). Serum samples obtained during acute illness from 221 hospitalized patients were examined using serology, RT-PCR, and virus isolation in cell culture: 59% of samples had laboratory evidence of a dengue infection. All 4 dengue virus serotypes (DEN 1-4) were identified in epidemic circulation, with DEN 3 predominating (43%). DEN 1 was the principal serotype associated with less severe dengue illness, suggesting that virulence may be, in part, a function of infecting serotype. The climatic influence of ENSO on rainfall and temperature in the months leading up to and during the outbreak was dramatic, and is likely to contribute to favourable outbreak conditions.

Adolescent↗

PubMedDate not supplied

JPEG compression of digital echocardiographic images: impact on image quality.

Routine echocardiograms are not handled digitally because of enormous storage needs. Image compression techniques can reduce memory requirements, but the impact on diagnostic content is unknown. We studied the effect of an internationally accepted compression algorithm called Joint Photographic Experts Group (JPEG) on digital echocardiographic images. Diagnostic and image quality of JPEG compressed, two-dimensional echocardiograms at ratios ranging from 4:1 to 40:1 was compared with that of uncompressed images both subjectively by a blinded expert panel (540 observations) and objectively by quantitative image-processing parameters (180 images). Accuracy of 432 measurements performed on compressed M-mode and spectral Doppler tracings was determined. Simultaneously acquired videotaped images and their never-compressed digital counterparts were compared quantitatively for image fidelity. This study demonstrates that the JPEG compression algorithm produces little degradation of echocardiographic images at compression ratios of at least 20:1, with less measured distortion than is produced by videotape recording. With JPEG, digital storage and retrieval in routine echocardiography are feasible.

Algorithms↗

PubMedDate not supplied

Digital compression of echocardiograms: impact on quantitative interpretation of color Doppler velocity.

To test the impact of Joint Photographic Expert Group (JPEG) compression on the quantitative data encoded in color Doppler echocardiographic images, digital images from transesophageal echocardiography and an in vitro model of proximal flow convergence were analyzed before and after JPEG compression with compression ratios (CRs) as high as 65:1. Even at the highest CRs, greater than 95% of the pixels were categorized correctly as representing structure (gray scale) and greater than 98% were categorized correctly as representing velocity (color) data. Furthermore, the velocities and flows recovered from the compressed images agreed well (r = 0.998 [velocities] and r = 0.998 [flows] for CR = 7:1, falling to r = 0.881 [velocities] and r = 0.930 [flows] at CR = 65:1; p < 0.001 for the linear trend with CR). There was similarly little shift in the location of the red-blue aliasing contour, rising from an error of 0.05 +/- 0.19 (mean +/- SD) mm at CR = 7:1 to a maximum error of 0.11 +/- 0.36 mm at CR = 44:1. Thus JPEG compression has little impact on the quantitative velocity data encoded within color Doppler echocardiograms, which should allow widespread acceptance of digital transmission and storage.

Echocardiography, Doppler, Color↗

PubMedDate not supplied

Digital storage of echocardiograms offers superior image quality to analog storage, even with 20:1 digital compression: results of the Digital Echo Record Access Study.

A large interobserver and intraobserver variability study was performed comparing both digitally compressed and uncompressed echocardiographic images with the same images recorded onto super-VHS video-cassette tape (the current standard). In a blinded, randomized fashion, 179 observers scored the diagnostic and image quality of 20 pairs of echocardiographic loops representing various pathologic conditions. Overall, the digital images were preferred to the S-VHS images both for image quality and diagnostic content (p < 0.0001) regardless of the background or experience level of the observer. Furthermore, uncompressed digital images and those compressed by the Joint Photographic Experts Group (JPEG) algorithm at ratios of 20:1 were judged equivalent. These findings show that digital compression may be used routinely in echocardiography, resulting in improved image and diagnostic quality over present standards.

Adult↗

PubMedDate not supplied

Three-dimensional segmentation of luminal and adventitial borders in serial intravascular ultrasound images.

Intravascular ultrasound (IVUS) provides exact anatomy of arteries, allowing accurate quantitative analysis. Automated segmentation of IVUS images is a prerequisite for routine quantitative analyses. We present a new three-dimensional (3D) segmentation technique, called active surface segmentation, which detects luminal and adventitial borders in IVUS pullback examinations of coronary arteries. The technique was validated against expert tracings by computing correlation coefficients (range 0.83-0.97) and William's index values (range 0.37-0.66). The technique was statistically accurate, robust to image artifacts, and capable of segmenting a large number of images rapidly. Active surface segmentation enabled geometrically accurate 3D reconstruction and visualization of coronary arteries and volumetric measurements.

Algorithms↗

PubMedDate not supplied

Effect of potato virus X on the mineral content of potato tubers.

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Minerals↗

PubMedDate not supplied

Synthesis and biological evaluation of boronated nucleosides for boron neutron capture therapy (BNCT) of cancer.

Several N-3 substituted carboranyl Thd analogs were synthesized. These agents as well as some non-boronated nucleosides were evaluated in phosphoryl transfer assays with recombinant human TK1 and TK2. For some carboranyl thymidine analogs, TK1 phosphorylation rates approached 38% that of thymidine. Their in vitro cytotoxicty appeared to correlate with the TK1 levels in the tested cells. In some cases increased uptake in tumor cell nuclei compared with the surrounding cytoplasm was detected in vitro.

Boron Compounds↗

PubMedDate not supplied

Nutritional regulation of the immune responses: basic considerations and practical applications.

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Aged↗

PubMedDate not supplied

Prothrombin complex concentrates for clinical use.

Prothrombin complex concentrates prepared for clinical use are reviewed with emphasis on frequently observed adverse reactions such as viral hepatitis and thromboembolic complications. Preparation procedures and quality control are described briefly, and the use of these concentrates in the treatment of hemophilia A patients who develop factor VIII inhibitors is also described. The causes of and methods for the detection of potential thrombogenicity are discussed and suggestions which may result in a safer product are made.

Animals↗

PubMedDate not supplied

Magnetic resonance imaging and ultrasonography in the diagnosis of a malignant peripheral nerve sheath tumor in a dog.

A 9-year-old male neutered mixed breed dog had a two-month history of progressive left thoracic limb lameness. There was electromyographic evidence of denervation potentials in all muscles of this limb. In magnetic resonance images a multilobulated, hyperintense mass was visible caudal to the middiaphysis of the left humerus on T-2 weighted images. The mass, which was isointense with surrounding tissue on T1 weighted images, extended proximally towards the brachial plexus. The mass was also visible as a fusiform structure of mixed echogenicity sonographically, although fine-needle aspiration performed at this time was nondiagnostic. A malignant peripheral nerve sheath tumor was diagnosed histopathologically.

Action Potentials↗

PubMedDate not supplied

Solitary nodular goiter. Review of cytomorphologic features in 441 cases.

OBJECTIVE: To study the cytomorphologic features of solitary nodular goiters (SNG). STUDY DESIGN: May-Grünwald-Giemsa-stained smears in 441 SNG diagnosed by ultrasonography and fine needle aspiration (FNA) and found to have optimum cellular material at review were subjected to detailed cytologic assessment. The age of the patients ranged from 11 to 75 years, with a median of 35. Male: female ratio was 69:372. The parameters for cytologic assessment included cellularity, colloid content, acinar formation, papillary formation, intranuclear cytoplasmic inclusions, nuclear grooves, marginal vacuoles, Hürthle cells and various inflammatory cells. Histopathology reports on thyroidectomy specimens were available in 27 cases from two Delhi hospitals. RESULTS: Hyperplastic nodules (68 cases) differed significantly from colloid goiters (269 cases) by having more cases with excessive cellularity, acinar formation and marginal vacuoles (P < .001). There was also a significant difference with respect to papillary formation and moderate-to-excessive colloid content (P < .001). As compared to hyperplastic nodules, neoplasms (60 cases) had a significantly higher number of cases with papillary formation, intranuclear inclusions and nuclear grooves but lower number of cases with marginal vacuoles (P < .01-.001). Among neoplasms, usual papillary carcinoma (19 cases) differed from follicular neoplasms (20 cases) with respect to acinar formation, papillary formation and nuclear grooves (P < .001). A significant difference was also observed with respect to colloid content and nuclear inclusions. Follicular variant of papillary carcinomas (FVPC) (10 cases) emerged as a distinct cytologic entity following review and differed from usual papillary carcinomas in having a higher number of cases with acinar formation, tubular formation and marginal vacuoles (P < .01-.001) and lower number of cases with nuclear grooves (P = .05). FVPC also differed from follicular neoplasms with respect to papillary formation, tubular formation, intranuclear inclusions and nuclear grooves (P < .01-.001). Overall cytohistologic agreement was achieved in 24 of 27 (88.9%) cases. CONCLUSION: Detailed cytologic assessment of FNA smears-in SNG was helpful in highlighting parameters that differentiate between various types of goiters.

Adolescent↗

PubMedDate not supplied

Effect of synthesis temperature and doping level on conductivity and structure of poly(3-methyl thiophene).

Poly(3-methyl thiophene) was synthesized by oxidative chemical polymerization technique using ferric chloride as the dopant in an inert atmosphere. Samples of different doping levels were prepared and analyzed by Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy, and direct current (DC) conductivity measurement at room temperature (300 K). Synthesis of the polymer was confirmed by FTIR studies. FTIR spectra showed a shift in the heterocyclic bands in the region of 700-1200 cm(-1) with a decrease in synthesis temperature. It was evident from the scanning electron micrographs that the surface structure of the polymer became denser with an increase in doping level. The measured DC conductivity increased initially up to the doping level of 0.8 M and then this increase tended to slow down. Samples having a doping level of 0.4 M were synthesized at 300, 280, and 270 K while maintaining the other synthesis parameters. The conductivity and yield were found to increase as the temperature of the polymerization decreased.

Chlorides↗