Biomedical subjects

Thomas K Pilgram

Publications and source records attributed to Thomas K Pilgram.

At least 19 recordsLinked to original sources

PubMed2005

Feasibility of combining MR perfusion, angiography, and 3He ventilation imaging for evaluation of lung function in a porcine model.

RATIONALE AND OBJECTIVE: To assess the feasibility of combining magnetic resonance (MR) perfusion, angiography, and 3He ventilation imaging for the evaluation of lung function in a porcine model. MATERIALS AND METHODS: Fourteen consecutive porcine models with externally delivered pulmonary emboli and/or airway occlusions were examined with MR perfusion, angiography, and 3He ventilation imaging. Ultrafast gradient-echo sequences were used for 3D perfusion and angiographic imaging, in conjunction with the use of contrast-agent injections. 2D multiple-section 3He imaging was performed subsequently via the inhalation of hyperpolarized 3He gas. The diagnostic accuracy of MR angiography for detecting pulmonary emboli was determined by two reviewers. The diagnostic confidence for different combinations of MR techniques was rated on the basis of a 5-point grading scale (5 = definite). RESULTS: The sensitivity, specificity, and accuracy of MR angiography for detecting pulmonary emboli were approximately 85.7%, 90.5%, and 88.1%, respectively. The interobserver agreement was very strong (k = 0.82). There was a clear tendency for confidence to increase when first perfusion and then ventilation imaging were added to the angiographic image (Wilcoxon signed ranks test, P = 0.03). CONCLUSION: The combination of the three methods of MR perfusion, angiography, and 3H ventilation imaging may provide complementary information on abnormal lung anatomy and function.

Administration, Inhalation↗

PubMed2005

Power injection of microcatheters: an in vitro comparison.

PURPOSE: To determine the tolerance of 0.021-inch and 0.027-inch microcatheters to power injection in an in vitro flow model. MATERIALS AND METHODS: Twenty-four microcatheters (0.021-inch, n = 13; 0.027-inch, n = 11) were injected with iothalamate meglumine through a flow model with use of a power injector and high-pressure tubing. Catheters used included Rebar (0.021-inch, n = 4; 0.027-inch, n = 4), Transit (0.021-inch, n = 3; 0.027-inch, n = 3), Renegade (0.021-inch, n = 4; 0.027-inch, n = 4), and Renegade STC-18 (0.021-inch, n = 2) models. Through the 0.021-inch microcatheters, 5-second injections were performed at an initial rate of 0.7 mL/sec. Injection rates were increased by 0.5 mL/sec and the process was repeated until the pressure approached 1,000 psi or catheter breakage occurred. A similar process was repeated for the 0.027-inch catheters starting at a rate of 3.4 mL/sec. RESULTS: The 0.021-inch catheters were injected 303 times and the 0.027-inch catheters were injected 210 times. Three catheter failures occurred, with all breaks occurring at pressures greater than manufacturer recommendations. The 0.027-inch catheters as a group tolerated significantly higher injection rates than the 0.021-inch catheters. Of the 0.021-inch catheters, the STC-18 also provided superior maximum flow and volume compared with the Renegade catheter. The Rebar catheter tolerated significantly lower maximum injection rates and volumes than the other 0.027-inch catheters. CONCLUSIONS: The majority of microcatheters can be power-injected in vitro at pressures far greater than manufacturer recommendations. When fractures occur, they are near the hub of the catheter. Significantly greater rates of injection are possible through 0.027-inch catheters.

Catheterization↗

PubMed2004

Coronary artery calcification: effect of size of field of view on multi-detector row CT measurements.

The effect of the size of the field of view (FOV) on coronary artery calcium measurements at multi-detector row computed tomography (CT) was assessed. Coronary multi-detector row CT was performed with an identical protocol in 100 consecutive subjects. CT images were reconstructed at different FOV sizes (210, 260, and 310 mm). Calcified coronary lesions were detected in all three image sets in 52 subjects. The FOV sizes tested for multi-detector row CT coronary screening had a negligible effect on coronary artery calcium measurements (P >/=.06). However, risk stratification decreased by one level in seven of 52 subjects when the FOV increased from 210 or 260 to 310 mm.

Adult↗

PubMed2004

Is coronary artery calcium mass related to Agatston score?

RATIONALE AND OBJECTIVES: The objective of this study was to investigate the relationship between the coronary calcium mass and Agatston score measured on multidetector row computed tomography. MATERIALS AND METHODS: Eighty-three consecutive subjects (60 men and 23 women) referred for coronary screening were examined prospectively by electrocardiogram-triggered sequential multidetector row computed tomography scan (4 x 2.5-mm collimation). Their coronary calcium was quantitated by means of the Agatston scoring and mass method. The values of score and mass were transformed by taking the natural logarithm (ln(value + 1)) to reduce skewness. The relationship between the mass and score was analyzed with multiple regression analysis. RESULTS: Fifty-one subjects had a total of 328 calcified lesions detected and measured. The relationship between the calcium mass and score in 51 subjects conformed well to a linear relationship (r2 = 0.96). When analyzed in the total of 328 lesions, the relationship had a good empiric fit with a nonlinear (quadratic) model (r2 = 0.96). The best-fit equation was ln(lesion mass + 1) = -0.87 + 0.67 x ln(lesion score + 1) + 0.10 x (ln(lesion score + 1) - 2.86)2. This relationship was consistent in different coronary vessels and at different heart levels (r2 = 0.96 - 0.99), although there was a higher image noise at lower heart levels (paired t-tests, P < .0001). CONCLUSION: A nonlinear (quadratic) relationship existed strongly and consistently between coronary calcium mass and score, demonstrating a possible cross-sectional conversion between the two measurements.

Aged↗

PubMed2004

Comparison of MELD and Child-Pugh scores to predict survival after chemoembolization for hepatocellular carcinoma.

PURPOSE: To compare the value of the Child-Pugh and Model for End-stage Liver Disease (MELD) scores to predict patient survival rates after transarterial chemoembolization (TACE) for hepatocellular carcinoma (HCC). MATERIALS AND METHODS: Eighty-seven patients underwent 169 TACE sessions. Child-Pugh and MELD values were calculated before initial treatment. Survival length was tracked from the date of the first TACE procedure. Transplant recipients were censored from the study at the time of surgery. Child-Pugh and MELD scores as well as bilirubin and albumin levels and International Normalized Ratio were placed in high and low categories defined by their respective medians. Patient survival was compared at 3 months, 6 months, 12 months, and 24 months, and patterns were tested with chi2 or Fisher exact tests. Survival over the entire period was examined with Kaplan-Meier analysis and differences were tested with log-rank tests. RESULTS: Mean and median survival times for all patients were 24 and 17 months, respectively. Sixteen patients were censored for transplantation at a mean of 12.9 months. MELD and Child-Pugh scores correlated well with each other (r = 0.68). Child-Pugh score (r = -0.35, P = .04) correlated more strongly with 12-month survival than did MELD score (r = -0.26, P = .12). After high/low score category division, a significantly greater survival difference was predicted by Child-Pugh score (27.2 months vs 10.3 months; P = .03) versus MELD score (27.5 months vs 15.8 months; P = .19). An albumin level greater than 3.4 g/dL was also associated with significantly improved survival (29.3 months vs 10.1 months; P = .0032). Survival differences between high-risk and low-risk groups at the 3-, 6-, 12-, and 24-month intervals were significant for low Child-Pugh scores and for albumin levels greater than 3.4 g/dL. Statistical significance was not approached at any of the time lengths with MELD scores. CONCLUSIONS: Child-Pugh score correlates better than MELD score to overall patient survival and is a better predictor than MELD score of survival at specific time points. Of the components of the Child-Pugh and MELD systems, albumin level is the most useful predictor of survival.

Albumins↗

PubMed2004

Estrogen and/or calcium plus vitamin D increase mandibular bone mass.

BACKGROUND: We have previously reported that estrogen/hormone replacement therapy (E/HRT) has beneficial effects on oral bone density over 3 years and that calcium and vitamin D supplementation has a lesser effect. Here we report on mandibular bone mass for 49 women (of the original cohort of 135) who continued in an additional 2-year, open-label extension. METHODS: Postmenopausal women were randomly assigned to receive calcium and vitamin D plus E/HRT, or calcium and vitamin D only. Regression analysis of mandibular bone mass over time was performed for each woman. RESULTS: Twenty-two of 26 women who took calcium and vitamin D plus E/HRT for 5 years had small mandibular bone mass increases (0.35 +/- 0.38%, P<0.001). Seventeen of 19 women who took only calcium and vitamin D for 3 years had increases in mandibular bone mass (0.74 +/- 0.89%, P<0.002). The largest gains in mandibular bone mass occurred during the first 3 years of the study. CONCLUSIONS: The data of this study indicate that E/HRT and/or calcium and vitamin D may result in increases of mandibular bone mass in postmenopausal women. Because of the long-term risks associated with E/HRT, caution should be exercised in prescribing E/HRT for prevention of chronic menopausal conditions.

Alveolar Bone Loss↗

PubMed2003

Coronary artery calcium: accuracy and reproducibility of measurements with multi-detector row CT--assessment of effects of different thresholds and quantification methods.

PURPOSE: To evaluate the effects of different thresholds and quantification methods on the accuracy and reproducibility of coronary calcium measurements with multi-detector row computed tomography (CT). MATERIALS AND METHODS: A cardiac CT phantom containing predetermined calcified cylinders was scanned. Calcium volume and mass were measured at various threshold values ranging from 80 to 230 HU. In 32 patients, two consecutive CT scans were obtained, and the coronary artery calcium score, volume, and mass were measured by one observer at 130- and 90-HU thresholds. Correlation analysis and analysis of variance were performed to evaluate the measurement errors in the phantom study and the interscan variability in the clinical study. RESULTS: In the phantom, mass measurement error varied with threshold and calcium density (P <.01). Mass error was strongly correlated with volume error (r = 0.91, P <.01) but with a much smaller range. In the clinical study, interscan variability of mass measurements was significantly lower than that with other measurement methods for both patients and individual vessels. For the patients, the mean interscan variability of calcium score, volume, and mass at the 130-HU threshold was 20.4%, 13.9%, and 9.3%, respectively. For all methods, interscan variability was not significantly different between the 130- and 90-HU thresholds (P >.05). CONCLUSION: The mass measurement is more accurate, less variable, and more reproducible in coronary calcium quantification than are measurements with other algorithms. Accurate quantification of calcium in each calcified plaque may require that the threshold be set individually, depending on the calcium density.

Algorithms↗

PubMed2003

Follow-up of infrainguinal graft thrombolysis: analysis of predictors of clinical success.

HYPOTHESIS: Thrombolysis is an accepted technique to salvage a failed infrainguinal bypass graft. Careful case selection, including consideration of the native arterial runoff and the type and location of the graft, will portend a better clinical outcome and prolonged graft patency. DESIGN: Retrospective study of an inception cohort of 91 acutely thrombosed grafts. SETTING: Academic tertiary care center. PATIENTS: We analyzed 91 consecutive occluded grafts in 69 patients for secondary graft patency and clinical outcome. INTERVENTION: Regional transcatheter thrombolysis. MAIN OUTCOME MEASURES: Technical success, secondary graft patency, and the need for major limb amputation. RESULTS: Immediate technical success resulting in restoration of flow was achieved in 80 (88%) of 91 cases. Angioplasty or additional surgical intervention (eg, patch, interposition graft, or jump graft to a more distal site) was performed in 44 subjects (64%). Longer duration of secondary patency was associated with synthetic vs vein grafts (P =.03), popliteal vs distal (tibial/pedal) insertion of the anastomosis (P =.008), and intact native arterial outflow (P =.003). Twenty-three cases required major limb amputation in the follow-up period, but 17 (74%) of these had reocclusion within 30 days of thrombolysis. Only 43 grafts (47%) were found to be patent at 1-year follow-up. CONCLUSIONS: In carefully selected cases, thrombolytic therapy is an effective means to restore limb viability in patients with occluded infrainguinal grafts. Long-term patency rates, although similar to those of surgical series, remain poor.

Aged↗

PubMed2003

Forefoot structural predictors of plantar pressures during walking in people with diabetes and peripheral neuropathy.

Various foot structures are thought to influence forefoot plantar pressures during walking. High peak plantar pressures (PPP) during walking in people with diabetes mellitus (DM) and peripheral neuropathy (PN) can cause skin breakdown. The question addressed by this study is "What are the primary forefoot structural factors that predict regional PPP during walking in groups of people with and without DM and PN?" Twenty people with DM and PN (mean age 55+/-9 years, 6 female, 14 male, BMI=33+/-8) and 20 people without DM, matched for gender, age, and BMI were tested. Measures of foot structure were taken from three-dimensional images constructed from spiral X-ray computed tomography. Peak plantar pressure data were recorded during walking. Hierarchical multiple regression analysis was used to predict regional PPP at the great toe and five metatarsal heads from selected structural and walking variables. Metatarsal phalangeal joint angle (hammer toe deformity) was the most important variable predicting pressure, accounting for 19-45% of the PPP variance at five of the six locations in the DM group. Soft tissue thickness, hallux valgus, and forefoot arthropathy were the most important predictors of PPP in the control group. Combinations of structural and walking variables accounted for 47-71% of the variance in the DM group and 52-83% of the variance of PPP during walking in the control group. These structural variables, especially hammer toe deformity, should be considered in attempts to develop strategies to reduce excessive forefoot PPP that may contribute to skin breakdown or other injury.

Diabetes Mellitus↗

PubMed2003

Aligning anatomical structure from spiral X-ray computed tomography with plantar pressure data.

OBJECTIVE: To determine the reliability of identifying the location of each metatarsal head from spiral X-ray computed tomography on a matrix type pressure sensor recording. DESIGN: Experimental; test-retest and within subject two-condition comparison. BACKGROUND: Plantar pressure data quantify the amount of pressure and the general location of pressure. Specific anatomical structures associated with the site of pressure can only be determined by registering radiological data to the pressure sensor. METHODS: Eighteen subjects, nine individuals without diabetes mellitus and nine individuals with diabetes mellitus, peripheral neuropathy, and a history of plantar foot ulcers, participated in plantar pressure testing and spiral X-ray computed tomography scanning of their foot. A registration technique was developed to align spiral X-ray computed tomography data with pressure sensor data. RESULTS: When mapping the metatarsal head locations to the pressure sensor 48 of 90 metatarsal head locations were identical between repeated test occasions (53.3%), 40 of 90 metatarsal head locations were one pixel (5.08 mm) different between repeated test occasions (44.4%), and 2 of 90 were two pixels different (2.2%). Ninety-eight percent of repeated measures replicated exactly or varied by one pixel. CONCLUSION: Anatomical data from spiral X-ray computed tomography scanning can be reliably co-registered with pressure data. RELEVANCE: The ability to match bony anatomy to pressure data allows better understanding of structural factors contributing to peak pressure, provides precise information for three-dimensional modeling of the foot, and can improve orthotic fabrication and modification aimed at reducing pressure on the bottom of the foot.

Diabetes Complications↗

PubMed2003

Improving mass measurement of coronary artery calcification using threshold correction and thin collimation in multi-detector row computed tomography: in vitro experiment.

RATIONALE AND OBJECTIVES: This in vitro study was designed to improve the accuracy of coronary calcium mass measurement from computed tomography (CT) images by developing threshold-based calcium CT number correction and thin-slice spiral techniques. MATERIALS AND METHODS: A cardiac CT phantom containing simulated calcified cylinders of known calcium density was scanned with sequential 4 x 2.5-, spiral 16 x 1.5-, and spiral 16 x 0.75-mm collimation on 4- and 16-detector row CT scanners. The images obtained from the spiral scans were reconstructed in various slice widths. The calcified cylinders were imaged and their mean CT number and size were measured at thresholds ranging from 50 to 390 Hounsfield unit. The calcium mass measured was compared with the actual value to determine errors, and threshold-based correction factors were derived to minimize the errors. RESULTS: The minimum amount of measurable calcium in 1-mm cylinder was 0.3 mg at the 16 X 1.5-mm protocol and 0.2 mg at the 16 x 0.75-mm protocol. Compared with 2.5-mm sequential protocol, thin-slice spiral protocols yielded a higher radiation exposure and lower or similar image noise levels. The error in calcium mass after correction was significantly smaller than that in measured mass (P < .0001) and was consistent between the imaging protocols (P = .49). The accuracy of mass measurements was clearly improved by using thin-slice imaging protocols especially in 200-mg/cm3 calcium density (P < .0001). CONCLUSION: The accuracy of calcium mass CT measurement can be improved by threshold-based calcium CT number correction and thin collimation spiral techniques.

Calcinosis↗

PubMed2003

Pregnancy outcomes after fallopian tube recanalization: oil-based versus water-soluble contrast agents.

PURPOSE: To determine the pregnancy outcomes in patients undergoing fallopian tube recanalization (FTR) with use of oil-based versus water-soluble contrast agents. MATERIALS AND METHODS: Ninety-three patients with unilateral or bilateral proximal tubal occlusion confirmed by hysterosalpingography or laparoscopy underwent FTR with use of water-soluble contrast material alone (n = 50) or also had an oil-based agent injected into each tube after recanalization (n = 43). Pregnancy rates and outcomes of the two groups were studied retrospectively. RESULTS: With respect to differences between groups, only the body mass index proved to be a significant predictor (oil, 28.4; water, 24.7; P =.008). Mean age, duration of infertility, type of infertility, and initial diagnosis were comparable. There was a weak trend toward a higher pregnancy rate in the oil-based contrast material group, but it was not significant (P =.64). The average time to pregnancy was 4.4 months with use of oil-based contrast material, compared to 7.7 months with use of only water-soluble contrast material (P =.03). CONCLUSION: The use of an oil-based agent had little effect on the rate of conception, but time to conception was reduced by more than 3 months.

Adult↗

PubMed2003

Validation of an angiographic method for estimating resting blood flow to distal tissue beds in the lower extremities.

PURPOSE: The authors propose to validate an angiographic scoring system that estimates the resting blood flow in the lower extremities in patients with peripheral vascular disease (PVD). MATERIALS AND METHODS: Twenty patients with PVD underwent lower-extremity angiography. For each patient, three readers used the proposed scheme to estimate flow within 23 separate vessel segments from the infrarenal aorta to the pedal vessels. Each reviewer scored each angiogram twice. The scheme includes not only an assessment of stenoses and occlusions but also corrections for collaterals. Flow reductions to muscles in the thigh and calf were calculated by multiplying the estimated flows in the series of vessels that lead to these regions. The consistency of the scoring scheme was assessed by calculating Pearson correlation coefficients for intra- and interobserver variability. The scoring scheme was also used to estimate the ankle-brachial index (ABI) and these estimates were compared to the known ABIs. RESULTS: Overall, the scoring scheme demonstrated very good intra- and interobserver agreement. Correlation coefficients were typically greater than 0.9. In general, the correlation coefficients for proximal vessels were higher than those for distal vessels. The scoring scheme also had minimal intra- and interobserver variability for estimated flows to distal tissue beds. Agreement was better for a series of vessels than it was for individual segments. The estimated ABIs correlated well with the measured ABIs in all but two cases. These outliers include one case in which the measured ABI was >1 as a result of noncompressible vessels and the estimated ABI correctly reflected PVD. In the second case, the ABI was near normal because of a patent peroneal artery and our estimated ABI was abnormally low because our estimation method failed to factor in the peroneal artery. CONCLUSIONS: The proposed angiography scoring system reproducibly estimated flow reductions to distal tissue beds. The authors plan to use this system as a research tool for evaluating new methods of assessing and treating PVD.

Adult↗

PubMed2003

Gadolinium, carbon dioxide, and iodinated contrast material for planning inferior vena cava filter placement: a prospective trial.

PURPOSE: To prospectively compare the diagnostic accuracy of CO(2) and gadolinium to iodinated contrast material for inferior vena cavography before inferior vena cava (IVC) filter placement. MATERIALS AND METHODS: Forty patients underwent injection of iodinated contrast material, CO(2), and gadolinium. Iodinated contrast material was used as the standard. Caval diameter was determined with calibrated software. Three readers blinded to contrast agent used measured the distance from the superior image border to the inferior margin of the renal veins and from the inferior image border to the iliac bifurcation. The measurements with CO(2) and gadolinium were compared to those with iodinated contrast material to obtain the interobserver and intraobserver variability. The presence or absence of caval thrombus and variant anatomy was noted. The same readers reexamined 12 studies in a separate session to determine intraobserver variability and correlation. RESULTS: Caval diameter differed by 0.4 mm or less for all three agents. Measurements with all agents were within 2 mm of each other for all patients. Gadolinium and CO(2) were not significantly different from one another in measuring caval diameter. At the initial reading, compared with iodinated contrast material, gadolinium had greater mean interobserver error in measuring the distance to the iliac bifurcation and both renal veins (range, 1.6-1.8 mm) than CO(2) (range, 0.2-1.4 mm). This finding, although statistically significant for gadolinium (P <.05), was of doubtful clinical relevance. Interobserver correlation was significantly worse for CO(2) at the levels of the iliac bifurcation (P =.02) and right renal vein (P =.008). Interobserver correlation for gadolinium was similar to that for iodinated contrast material at all levels. At repeat reading, there was significantly inferior intraobserver correlation with use of CO(2) for both renal veins (P <.05) compared to iodinated contrast material and for the left renal vein (P <.05) compared to gadolinium. Gadolinium identified three of three renal vein anomalies identified with iodinated contrast material whereas CO(2) localized one of three. CONCLUSION: CO(2) and gadolinium had limitations when compared with iodinated contrast material. Gadolinium provided superior consistency in identifying relevant landmarks for filter placement. CO(2) demonstrated significantly greater mean correlative error than gadolinium at initial and repeat readings.

Aged↗

PubMed2003

Endovascular recanalization of the thrombosed filter-bearing inferior vena cava.

PURPOSE: To evaluate the authors' preliminary experience with use of endovascular methods to treat inferior vena cava (IVC) thrombosis in patients with IVC filters. MATERIALS AND METHODS: Catheter-directed thrombolysis, balloon maceration, mechanical thrombectomy, and stent placement were used to treat 10 patients with thrombosis of filter-bearing IVCs causing symptoms in 18 limbs. Procedural challenges, technical and clinical success, complications, postprocedural filter status, and postprocedural pulmonary embolism (PE) prophylaxis were monitored. RESULTS: Technical and clinical success were achieved in 15 of 18 (83%) and 14 of 18 symptomatic limbs (78%), respectively. Major bleeding (muscular hematoma) occurred in one patient (10%). Postprocedural PE prophylaxis included anticoagulation (n = 8) and placement of a new filter into a newly placed Wallstent (n = 1). During clinical follow-up, no clinically detectable PE was observed. Data pertaining to late limb status were available at a median of 19 months (range 1-46 months) follow-up in seven patients: three patients were asymptomatic, two patients had ambulatory edema only, one patient had constant mild edema, and one patient had constant severe edema. Postprocedural filter stability was radiographically documented at a median of 255 days (range, 4-1021 d) of follow-up. CONCLUSION: Endovascular recanalization of the occluded IVC is feasible even in the presence of an IVC filter.

Adult↗

PubMed2003

Coronary artery calcium quantification at multi-detector row CT: influence of heart rate and measurement methods on interacquisition variability initial experience.

PURPOSE: To assess the effect of heart rate on interacquisition variability in different coronary calcium quantification methods at multi-detector row computed tomography (CT). MATERIALS AND METHODS: Fifty consecutive adults (39 men and 11 women; mean age, 57 years +/- 13 [SD]) with various heart rates were examined with two prospectively electrocardiographically triggered multi-detector row CT acquisitions in succession for detection and quantification of coronary artery calcification. Calcium score, volume, and mass were measured for each acquisition. Interacquisition variability was evaluated in association with heart rate and quantification method in subjects and individual coronary vessels by using t tests and analysis of variance. RESULTS: In 37 subjects with detected calcium, interacquisition variability in mass measurement (10.4%) was significantly lower than that in score (23.9%) and volume (15.7%) measurements (P <.02). The interacquisition variability in all quantification methods was well correlated with heart rate and was considerably greater when heart rates were higher than 70 beats per minute (bpm) than when heart rates were 70 bpm or lower (P <.002). There was a clear tendency for interacquisition variability to vary by vessel (P <.01). The correlation of interacquisition variability with heart rate and a significant difference in interacquisition variability between the group with heart rates of 70 bpm or lower and the group with rates higher than 70 bpm (P <.02) were found for the left main and left anterior descending arteries but not for the circumflex and right coronary arteries. CONCLUSION: Interacquisition variability in coronary calcium measurements at multi-detector row CT is significantly less at lower heart rates. The coronary calcium mass measurement is more reproducible than are score and volume measurements.

Adult↗

PubMed2003

Irreversible JPEG compression of digital chest radiographs for primary interpretation: assessment of visually lossless threshold.

PURPOSE: To determine if digital chest images could be compressed in a primary interpretation context without perceived loss of fidelity (below the visually lossless threshold) at transilluminated film or cathode ray tube (CRT) display. MATERIALS AND METHODS: One hundred forty-four posteroanterior radiographs were obtained with a digital chest radiography system. At both film and CRT display, an identified original image was presented side by side with a replicate, which was either an unaltered image or an image that had been Joint Photographic Experts Group (JPEG) compressed to 10:1, 20:1, or 50:1 and reconstructed. Each of the 10 readers indicated whether the replicate was "indistinguishable from the original" or "degraded" at clinical reading distance and at close inspection. The readers' ability to detect compressed images was examined for patterns; 95% CIs were used for statistical testing. RESULTS: With transilluminated film at clinical reading distance, readers were as likely to rate originals (48 [20%] of 240 readings) as degraded as they were to rate 20:1 replicates (106 [22%] of 480 readings) as degraded, but they frequently identified 50:1 replicates (283 [59%] of 480 readings) as degraded. At close inspection, 20:1 replicates (163 [34%] of 480 readings) were often identified as degraded, but 10:1 replicates (19 [8%] of 240 readings) were not identified as degraded more often than originals (17 [7%] of 240 readings). With CRT display, the results were nearly identical. CONCLUSION: At reading distance for primary interpretation, full-size digital chest radiographs that have been JPEG compressed to 10:1 or 20:1 and reconstructed are visually lossless at film or CRT display. Images compressed to 10:1 remain visually lossless at close inspection.

Algorithms↗

PubMed2003

Variation in diaphragm position and shape in adults with normal pulmonary function.

BACKGROUND: Diaphragm position and shape on chest radiographs are routinely used as indicators of normal or abnormal lung volume. However, previous population studies of normal diaphragm position and shape frequently lack objective radiographic measurements and documentation of pulmonary function, and do not account for the observed variability. STUDY OBJECTIVE: s: To determine the spectrum of diaphragm position and shape on chest radiographs using objective measurements, in patients with normal pulmonary function, and to identify the relationship of diaphragm position and shape to demographic variables and radiographic thoracic dimensions. DESIGN: Prospective cross-sectional observational study. SETTING: University hospital. PATIENTS: One hundred fifty-three adults with normal FEV(1) (>or= 80% predicted) and normal total lung capacity (80 to 120% predicted). MEASUREMENTS AND RESULTS: Diaphragm position and shape relative to anatomic landmarks were determined from posteroanterior and lateral chest radiographs. We used descriptive statistics to calculate normal values, and linear correlation, two-tailed t tests, and multivariate analysis to relate findings to age, weight, gender, and thoracic dimensions. The right hemidiaphragm dome was positioned at 9.7 +/- 0.8 thoracic vertebral levels (body plus disk space) [mean +/- SD] below the top of the first thoracic vertebra (range, 7.4 to 11.3 vertebral levels), and the left hemidiaphragm dome was positioned at 10.2 +/- 0.8 vertebral levels (range, 8.1 to 11.8 vertebral levels). The right hemidiaphragm radius was 13.8 +/- 3.8 cm (range, 7.2 to 29.6 cm), and the ratio between the height and the anteroposterior dimension of the right hemidiaphragm was 0.23 +/- 0.05 cm (range, 0.08 to 0.36 cm). The diaphragm tended to be lower with higher age, lower weight, and smaller transverse and anteroposterior thoracic dimensions (r = 0.22 - 0.47, p < 0.05), and flatter (larger radius) with higher age, weight, transverse thoracic dimension, pack-years smoked (r = 0.32 - 0.42, p < 0.0001), and male gender (p < 0.0001). The tested variables accounted for approximately one third of the variability in diaphragm position and shape (multivariate R(2) = 0.31 - 0.38). CONCLUSIONS: The substantial variability in normal diaphragm position and shape is related to weight, age, and thoracic dimensions. Consideration of these factors may be useful when evaluating chest radiographs.

Adult↗