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Henry Rusinek

Publications and source records attributed to Henry Rusinek.

8 recordsLinked to original sources
PubMed2003

Wavelet compression of low-dose chest CT data: effect on lung nodule detection.

PURPOSE: To assess the effect of using a lossy Joint Photographic Experts Group standard for wavelet image compression, JPEG2000, on pulmonary nodule detection at low-dose computed tomography (CT). MATERIALS AND METHODS: One hundred sets of lung CT data ("cases") were compressed to 30:1, 20:1, and 10:1 levels by using a wavelet-based JPEG2000 method, resulting in 400 test cases. Each case consisted of nine 1.25-mm sections that had been obtained with 20-40 mAs. Four thoracic radiologists independently interpreted the test case images. Performance was measured by using area under the receiver operating characteristic (ROC) curve (Az) and conventional sensitivity and specificity analyses. RESULTS: There were 51 cases with and 49 without lung nodules. Az values were 0.984, 0.988, 0.972, 0.921, respectively, for original and 10:1, 20:1, and 30:1 compressed images. Az values decreased significantly at 30:1 (P =.014) but not at 10:1 compression, with a trend toward significant decrease at 20:1 (P =.051). Specificity values were unaffected by compression (>98.0% at all compression levels). Sensitivity values were 86.3% (176 of 204 test cases with nodules), 77.9% (159 of 204 cases), 76.5% (156 of 204 cases), and 70.1% (143 of 204 cases), respectively, for original and 10:1, 20:1, and 30:1 compressed images. Results of logistic regression model analysis confirmed the significant effects of compression rate and nodule attenuation, size, and location on sensitivity (P <.05). CONCLUSION: While no reduction in nodule detection at 10:1 compression levels was demonstrated by using ROC analysis, a significant decrease in sensitivity was identified. Further investigation is needed before widespread use of image compression technology in low-dose chest CT can be recommended.

Humans↗
PubMed2003

Dynamic three-dimensional MR renography for the measurement of single kidney function: initial experience.

A three-dimensional magnetic resonance (MR) renographic method to measure single kidney glomerular filtration rate (GFR) and split renal function was developed that is based on renal signal intensity measurements during 2-3 minutes after intravenous injection of a low dose (2 mL or 0.01 mmol/kg) of gadopentetate dimeglumine. In nine subjects, single kidney MR GFR indices correlated well with technetium 99m (99mTc) diethylenetriaminepentaacetic acid (DTPA) clearance (r = 0.7-0.8) for GFR values of 7-48 mL/min. MR right kidney split renal function values (range, 32%-59%) also correlated well with 99mTc-DTPA radionuclide measurements (r = 0.76); differences between the two methods averaged 0.8% +/- 8. MR renography was performed along with contrast material-enhanced MR imaging of the kidneys and renal arteries and added 8 minutes or less to the total examination time.

Adult↗
PubMed2003

Diffusely elevated cerebral choline and creatine in relapsing-remitting multiple sclerosis.

It is well known that multiple sclerosis (MS) pathogenesis continues even during periods of clinical silence. To quantify the metabolic characteristics of this activity we compared the absolute levels of N-acetylaspartate (NAA), creatine (Cr), and choline (Cho) in the normal-appearing white matter (NAWM) between relapsing-remitting (RR) MS patients and controls. Metabolite concentrations were obtained with 3D proton MR spectroscopy at 1.5 T in a 480 cm(3) volume-of-interest (VOI), centered on the corpus callosum of 11 MS patients and 9 matched controls. Gray/white-matter/cerebral-spinal-fluid (CSF) volumes were obtained from MRI segmentation. Patients' average VOI tissue volume (V(T)), 410.8 +/- 24.0 cm(3), and metabolite levels, NAA = 6.33 +/- 0.70, Cr = 4.67 +/- 0.52, Cho = 1.40 +/- 0.17 mM, were different from the controls by -8%, -9%, +22% and +32%. The Cho level was the only single metric differentiating patients from controls at 100% specificity and >90% sensitivity. Diffusely elevated Cho and Cr probably reflect widespread microscopic inflammation, gliosis, or de- and remyelination in the NAWM. Both metabolites are potential prognostic indicators of current disease activity, preceding NAA decline and atrophy.

Adult↗
PubMed2003

Small pulmonary nodules: volume measurement at chest CT--phantom study.

Three-dimensional methods for quantifying pulmonary nodule volume at computed tomography (CT) and the effect of imaging variables were studied by using a realistic phantom. Two fixed-threshold methods, a partial-volume method (PVM) and a variable method, were used to calculate volumes of 40 plastic nodules (largest dimension, <5 mm: 20 nodules with solid attenuation and 20 with ground-glass attenuation) of known volume. Tube current times (20 and 120 mAs), reconstruction algorithms (high and low frequency), and nodule characteristics were studied. Higher precision was associated with use of a PVM with predetermined pure nodule attenuation, high-frequency algorithm, and diagnostic CT technique (120 mAs). A PVM is promising for volume quantification and follow-up of nodules.

Algorithms↗
PubMed2002

Cognitive performance in schizophrenia: relationship to regional brain volumes and psychiatric symptoms.

In an all-male sample of schizophrenic patients stabilized by medication (n=62) and normal controls (n=27), we obtained neuropsychological test data and high-resolution whole brain magnetic resonance scans, as well as detailed psychiatric rating scales on a subset of the patients (n=47). Schizophrenic patients had significantly worse overall age-adjusted cognitive performance than normal controls (average z-score=-0.90, range=-0.60 to -1.81), which included relatively more severe deficits with different types of memory, psychomotor speed, verbal fluency and verbal abstraction. Schizophrenic patients also had significantly smaller bilateral volumes in gray but not white matter in the prefrontal region, superior temporal gyrus and whole temporal lobe, but no group differences were observed in the hippocampus and parahippocampus. Correlations between the brain regions and cognitive performance revealed different sets of significant relationships for the two groups, particularly in the prefrontal and hippocampal regions. In addition, inverse correlations were observed between certain cognitive abilities (psychomotor speed, cognitive flexibility and verbal fluency) and patients' psychiatric ratings, especially with measures of negative symptoms. The convergence of findings for schizophrenic patients regarding the prefrontal region, negative symptoms, psychomotor speed and cognitive flexibility suggests that schizophrenic negative symptoms may involve disruption of frontal-subcortical connections.

Adult↗
PubMed2002

Computed tomography diagnosis utilizing compressed image data: an ROC analysis using acute appendicitis as a model.

Using receiver-operating characteristic (ROC) methodology, the ability to diagnose acute appendicitis with computed tomography (CT) images displayed at varying levels of lossy compression was evaluated. Nine sequential images over the ileocecal region were obtained from 53 consecutive patients with right lower quadrant pain who were clinically suspected to have acute appendicitis. Thirty were proven surgically to have acute appendicitis, alternative diagnoses confirmed in 23. The image sets were subjected to a lossy wavelet-based compression algorithm "Embedded Predictive Wavelet Image Coder" (EPWIC). Compression levels were: none, 8:1, 16:1, and 24:1, resulting in 4 sets of images per patient. Image sets were randomized and evaluated separately by 4 body radiologists on a 1,024 x 768-pixel SVGA color PC monitor in 512 x 512 format. The readers were aware of the clinical suspicion of appendicitis but were unaware of the positive fraction of cases. Individual and combined reader ROC and c2 analyses of sensitivity, specificity, and accuracy were determined. For all readers, sensitivity decreases at 16:1 and 24:1 levels (P <0.01, P <0.001, respectively). Accuracy decreased at 24:1 levels (P <0.01). Specificity was unaffected. By ROC analysis there was statistically significantly decreased area under the curve at 24:1 levels (P <0.02) as compared with uncompressed images. Finite levels of lossy wavelet compression may be applied to CT images without compromising diagnostic performance.

Acute Disease↗
PubMed2002

CT findings in acute gangrenous cholecystitis.

OBJECTIVE: The purpose of this study was to determine the CT findings in acute gangrenous cholecystitis. MATERIALS AND METHODS: Four observers retrospectively reviewed CT scans in 75 patients (23 with acute gangrenous cholecystitis, 25 with acute non-gangrenous cholecystitis, and 27 without cholecystitis). The following findings were evaluated: distention, mural thickening, wall enhancement, irregular wall, wall striation, intraluminal membranes, pericholecystic inflammation, gallstones, pericholecystic fluid, enhancement of liver parenchyma, pericholecystic abscess, and gas in the wall or lumen. Sensitivity and specificity of CT for gangrenous cholecystitis and for each finding were calculated. Two reviewers in consensus measured gallbladder dimension and wall thickness. Logistic regression models were used to predict gangrenous versus non-gangrenous cholecystitis. RESULTS: Sensitivity, specificity, and accuracy of CT for acute cholecystitis were 91.7%, 99.1%, and 94.3%, respectively, and for acute gangrenous cholecystitis were 29.3%, 96.0%, and 64.1%, respectively. Findings with the highest specificity for gangrenous cholecystitis were gas in the wall or lumen (100%), intraluminal membranes (99.5%), irregular or absent wall (97.6%), and abscess (96.6%). The difference between the mean gallbladder wall thickness and the short-axis dimension for the two groups with cholecystitis was statistically significant. In three patients with gangrenous cholecystitis, no mural enhancement was seen. Pericholecystic fluid also achieved statistical significance for the diagnosis of gangrene. Multivariate logistic regression analysis showed that the overall accuracy of CT for gangrenous cholecystitis was 86.7%. CONCLUSION: CT findings most specific for acute gangrenous cholecystitis are gas in the wall or lumen, intraluminal membranes, irregular wall, and pericholecystic abscess. Gangrenous cholecystitis is associated with a lack of mural enhancement, pericholecystic fluid, and a greater degree of gallbladder distention and wall thickening.

Acute Disease↗