SEARCH · PubMed Health

Results for “COMPRESSION”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 397 records · Page 22Linked to original sources

PubMed1999

The effects of external compression on venous blood flow and tissue deformation in the lower leg.

External pneumatic compression of the lower legs is effective as prophylaxis against deep vein thrombosis. In a typical application, inflatable cuffs are wrapped around the patient's legs and periodically inflated to prevent stasis, accelerate venous blood flow, and enhance fibrinolysis. The purpose of this study was to examine the stress distribution within the tissues, and the corresponding venous blood flow and intravascular shear stress with different external compression modalities. A two-dimensional finite element analysis (FEA) was used to determine venous collapse as a function of internal (venous) pressure and the magnitude and spatial distribution of external (surface) pressure. Using the one-dimensional equations governing flow in a collapsible tube and the relations for venous collapse from the FEA, blood flow resulting from external compression was simulated. Tests were conducted to compare circumferentially symmetric (C) and asymmetric (A) compression and to examine distributions of pressure along the limb. Results show that A compression produces greater vessel collapse and generates larger blood flow velocities and shear stresses than C compression. The differences between axially uniform and graded-sequential compression are less marked than previously found, with uniform compression providing slightly greater peak flow velocities and shear stresses. The major advantage of graded-sequential compression is found at midcalf. Strains at the lumenal border are approximately 20 percent at an external pressure of 50 mmHg (6650 Pa) with all compression modalities.

Blood Flow Velocity↗

PubMed1992

Arterial hypertension and neurovascular compression at the ventrolateral medulla. A comparative microanatomical and pathological study.

Intraoperative observations and animal experiments suggest that neurovascular compression at the left ventrolateral medulla is a possible etiological factor in essential hypertension. In pursuing this hypothesis, the authors examined the neurovascular relations in the posterior cranial fossa of 24 patients with essential hypertension, of 10 with renal hypertension, and of 21 normotensive control patients. Artificial perfusion of the vessels and microsurgical investigations during autopsy identified the vascular relations at the brain stem and at the root entry zone of the caudal cranial nerves. There was no evidence of neurovascular compression at the ventrolateral medulla on the left side in any patient from the control group or among those with renal hypertension. Two normotensive patients had neurovascular compression at the right ventrolateral medulla by the posterior inferior cerebellar artery. In contrast, all patients with essential hypertension had definite neurovascular compression at the left ventrolateral medulla. Additional compression of the right side was seen in three of these patients. Based on the anatomical appearance, it was possible to define three distinct types of neurovascular compression at the ventrolateral medulla. Common to all three types is the compression of the medulla oblongata at its rostral part just caudal to the pontomedullary junction and lateral to the olive in the retro-olivary sulcus. Comparative histopathological study of the microsurgically examined brain-stem specimens revealed no differences between patients with essential hypertension, those with renal hypertension, and normal controls. There was a structural integrity at the site of neurovascular compression at the ventrolateral medulla. The microanatomical findings of this study show that neurovascular relations at the ventrolateral medulla in essential hypertension give rise to pulsatile compression on the left. This supports Jannetta's hypothesis of neurovascular compression at the left ventrolateral medulla as an etiology of essential hypertension.

Adult↗

PubMed1999

[Electrophysiological evaluation of level compression in elbow ulnar neuropathy].

OBJECTIVES: In order to establish the focal compression in the elbow, a study of 318 patients with clinical manifestations of ulnar neuropathy was carried out. We divided the patients in three groups: I) those who presented mechanical anomalies with background of fracture, elbow valgus...; II) those who did not present mechanical anomalies, but they have been in bed long time or they have been operated...; III) those who did not have evident cause for the compression. MATERIAL AND METHOD: Antidromic sensory conduction and segmentary motor conduction of the ulnar nerve were studied, and segmental motor conduction along the elbow with interval of 2 centimetres (technique of Kanakamedala). RESULTS: 83.6% of the 318 ulnar neuropathy had the focal compression in the ulnar sulcus. 8.2% had the focal compression distal to the ulnar sulcus. 0.94% had double focal compression. In 7.2% was not possible to determinate the focal compression. In group I, the focal compression was in the ulnar sulcus in 93.8% of the cases. In group II, the focal compression was in the ulnar sulcus in 94.3% of the cases. In group III, the focal compression was in the ulnar sulcus in 55.8% of the cases, and distal to the ulnar sulcus in 29.1% of the cases. CONCLUSION: It is possible to localize the focal compression of the ulnar neuropathy in the elbow, with high level of probability, with the nerve conductions. This allows the surgeon to be orientated about therapeutical attitude.

Adult↗

PubMed1992

[Compression neuropathy of the cubital nerve at the elbow].

Compression neuropathy of the ulnar nerve at the elbow has numerous known etiologies, and the anatomy of the ulnar nerve around the elbow leaves it vulnerable to compression at numerous sites. The compression may be extrinsic such as in occupational neuropathy or in cases of postanesthesia neuropathy. The so-called idiopathic compression may be favored by some anatomic variations. The cubital tunnel retinaculum may be loose, leading to ulnar nerve dislocation or subluxation or tight compression of the nerve during flexion of the elbow. Bulging of the synovium in the floor of the tunnel may be the cause of compression in rheumatoid arthritis, whereas osteophytes may be the cause in degenerative osteoarthritis. Cubitus valgus or instability due to a pseudarthrosis of the lateral epicondyle or to ligamentous injury may stretch the nerve. The choice of a surgical technique must be based on (i) the pathophysiology of chronic nerve compression at the elbow, (ii) an understanding of the etiology of the nerve compression in the particular patient's case, and (iii) the knowledge of the potential technical drawbacks of the various operative procedures. Simple decompression is the first choice in case of minimal compression without instability of the nerve. Decompression of the nerve with a medial epicondylectomy is indicated in case of instability of the nerve and is the first choice in case of pseudarthrosis or malunion of the medial epicondyle. Ulnar nerve transposition is technically the most demanding procedure. Inadequate surgical technique creates new sites of compression.(ABSTRACT TRUNCATED AT 250 WORDS)

Elbow↗

PubMed1986

Pathology of experimental nerve compression.

Acute, graded, nerve compression was applied to the sciatic nerves of 91 rats in whom an inflatable miniature Plexiglass compression device had been implanted in the thigh. The experiment was designed to study the pathogenesis of lesions in the nerve entrapment syndrome. Under general anesthesia, external pressures of 80 mm of Hg, 30 mm of Hg and 10 mm of Hg were used to compress nerves for 2 hours. Identical compression devices were placed around the contralateral sciatic nerves but remained uninflated so that these nerves could be used as controls. Nerves were excised at intervals of 4 and 24 hours, and at 1, 2, 5, 6, 7, 10, 14, and 28 days, and full thickness transverse sections were made from Araldite blocks. The first pathologic change was nerve edema which was observed at all time points and correlated with the severity of axonal injury. Axonal lesions were predominant in nerves exposed to 80 mm of Hg (7.5 +/- 1.9 nerve fibers per high power microscopic field (HPF)) while nerves compressed at 30 mm of Hg showed fewer damaged axons (2.6 +/- 1.4 per HPF). Demyelination was the predominant lesion in nerves subjected to 30 mm of Hg and was commonly present in nerves around which the compression chamber remained uninflated. Electron microscopy revealed demyelination to be associated with Schwann cell necrosis. The topography of nerve fiber injury was remarkable; subperineurial fibers were often damaged after compression of nerves in which nerve fibers at the core of the fascicle remained unaffected. The findings suggest that local external compression causes ischemia in nerve fibers served by transperineurial vessels, with severe compression causing axonal damage, while lesser degrees of compressive injury are associated with demyelination.

Animals↗

PubMed1992

Do graduated compression stockings and pneumatic boots have an additive effect on the peak velocity of venous blood flow?

Graduated compression stockings and intermittent pneumatic compression boots reduce the incidence of deep vein thrombosis. Recent studies suggest that the simultaneous use of these devices may have a synergistic prophylactic effect; however, conflicting reports also exist. Using duplex imaging, we analyzed the effect on peak venous velocity in the superficial femoral vein produced by the individual and simultaneous use of graduated compression stockings and intermittent pneumatic compression boots. Normal volunteers and postoperative patients were examined. The use of intermittent pneumatic compression boots significantly increased the peak venous velocity relative to rest, whereas the use of graduated compression stockings did not alter the peak venous velocity. Also, the addition of graduated compression stockings to legs already being treated with intermittent pneumatic compression boots did not produce a further augmentation of peak venous velocity. This study demonstrates that the simultaneous use of graduated compression stockings and intermittent pneumatic compression boots does not produce a synergistic augmentation of peak venous velocity in the superficial femoral vein.

Bandages↗

PubMed1998

Isovolume pressure/flow curves of rapid thoracoabdominal compressions in infants without respiratory disease.

To assess whether flow limitation can be achieved during rapid thoracoabdominal compressions (RTC), we performed esophageal pressure measurements in 11 healthy infants less than 3 months of age. Recordings of esophageal pressure were obtained with an esophageal balloon placed in the lower esophagus. RTCs were started at 20 cm H2O and increased to 140 cm H2O or until the infant responded with glottic closure to the compression. Flow limitation was assessed from isovolume pressure flow curves at peak flow and flow at FRC (V'max, FRC). The transmission of jacket pressure was higher at peak flow than at FRC for pressures below 60 cm H2O, due to active inspiration during the compression. Active inspiration was not observed at compression pressures above 80 cm H2O, as reflected by a plateau in the esophageal pressure tracing. Esophageal pressure increased parallel to the compression pressure at jacket pressures below 60 cm H2O. The relationship between jacket pressure and esophageal pressure became curvilinear at high compression pressures and plateaued at compressions above 100 cm H2O, so that further increases in jacket pressure did not increase esophageal pressure. Flow limitation was seen in all infants studied, as indicated by a lack of increase in flow with increasing esophageal pressures for V'max, FRC. Jacket compression pressures of 60 cm H2O and esophageal pressures of 20 cm H2O were sufficient to reach maximal expiratory flow. These data indicate that jacket pressure is a poor indicator of pleural pressure at high compression pressures in young healthy infants, and high pressures are not needed, as flow limitation is seen during RTCs at moderate compression pressures.

Esophagus↗

PubMed2001

Effect of compression on fast swelling of poly(acrylamide-co-acrylic acid) superporous hydrogels.

Superporous hydrogels (SPHs) swell to a large size in a very short time. In many applications it is preferred to compress SPHs to reduce the overall dimension in the dried state. The effects of compression on the swelling property of SPHs were examined. The swelling property of the compressed SPHs was dependent on the orientation of the SPHs during compression. If SPHs were compressed in an orientated manner so that they retained interconnected porous structure, they were able to swell to near equilibrium within 10 min of immersion in aqueous fluids. If SPHs were compressed in a manner that did not retain the open pore structure, the swelling rate was greatly reduced. The results showed that the SPHs could be compressed without significant sacrifice of the fast swelling property if compressed in a proper orientation. Because pores were formed owing to the generation of gas which rose from bottom to the top of the container, the compression parallel to the pore formation resulted in preservation of the pore structure, and thus fast swelling property. The ability to compress SPHs, maintaining the fast swelling property, is expected to be useful in various applications including development of gastric retention devices for oral drug delivery.

Acrylamides↗

PubMed1999

Influences of inflation rate and duration on vasodilatory effect by intermittent pneumatic compression in distant skeletal muscle.

Previous study has demonstrated that application of intermittent pneumatic compression on legs can cause vasodilation in distant skeletal muscle at the microcirculation level. This study evaluated the influence of inflation rate and peak-pressure duration on the vasodilatory effects of intermittent pneumatic compression. The cremaster muscles of 50 male rats were exposed and divided into five groups of 10 each. A specially designed intermittent pneumatic-compression device was applied in a medial-lateral fashion to both legs of all rats for 60 minutes, with an inflation rate and peak-pressure duration of 0.5 and 5 seconds, respectively, in group A, 5 and 0 seconds in group B, 5 and 5 seconds in group C, 10 and 0 seconds in group D, and 10 and 5 seconds in group E. Diameters of arterial segments were measured in vessels of three size categories (10-20, 21-40, and 41-70 microm) for 120 minutes. The results showed that the greatest increase in diameter was produced by intermittent pneumatic compression with the shortest inflation rate (0.5 seconds). A moderate increase resulted from compression with an inflation rate of 5 seconds, and no effective vasodilation occurred during compression with the longest inflation rate (10 seconds). When the groups with different inflation rates but the same peak-pressure duration were compared, there was a significant difference between any two groups among groups A, C, and E and between groups B and D. When the groups with different peak-pressure durations but the same inflation rate were compared, compression with a peak-pressure duration of 5 seconds caused a generally similar degree of diameter change as did compression without inflation at peak pressure. The findings suggest that inflation rate plays an important role in the modulation of distant microcirculation induced by intermittent pneumatic compression whereas peak-pressure duration does not significantly influence the vasodilatory effects of the compression. This may be due to the fact that rapid inflation produces a significant increase in shear stress on the vascular wall, which stimulates vascular endothelium to release nitric oxide, causing systemic vasodilation.

Animals↗

PubMed1996

Compression of cartilage results in differential effects on biosynthetic pathways for aggrecan, link protein, and hyaluronan.

The differential effects of static compression and recovery from compression on biosynthesis and biosynthetic pathways of aggrecan, link protein, and hyaluronan were assessed. During compression, biosynthesis of aggrecan and link protein were inhibited to approximately 25 and approximately 40%, respectively, of free-swelling control levels. In marked contrast, hyaluronan synthesis was unaffected by static compression. After release from 12-h 50% static compression, aggrecan synthesis remained inhibited for up to 2.5 days; however, link protein synthesis completely recovered to free-swelling control levels within 8 h after release. Hyaluronan synthesis remained at control levels after release of compression. During compression, aggrecan core protein pool size was decreased, whereas the rate of processing into the proteoglycan form remained essentially the same as in free swelling control tissue. Four hours after release from compression, aggrecan core protein pool size remained small and the rate of intracellular processing of aggrecan had become slower than that of free swelling control tissue. Due to the altered core-protein processing kinetics, fewer but longer chondroitin sulfate chains were added to the core proteins. Sulfation was not markedly altered. The differential effects of static compression and release on the biosynthesis of aggrecan, link protein, and hyaluronan are similar to the changes in the biosynthetic pathways that are affected in response to IL-1 treatment, suggesting that the response to static compression is not a general inhibition of cellular activity, but appears to be part of a specific transduction mechanism.

Aggrecans↗

PubMed1998

Load-controlled compression of articular cartilage induces a transient stimulation of aggrecan gene expression.

The effects of short- and long-term load-controlled compression on the levels of aggrecan mRNA have been determined. Results show that a compressive stress of 0.1 MPa on bovine articular cartilage explants for 1, 4, 12, and 24 h produces a transient up-regulation of aggrecan mRNA synthesis. At 1 h, aggrecan mRNA levels in loaded explants were increased 3.2-fold compared to control explants. At longer times (>/=4 h), the levels of aggrecan mRNA returned to baseline values or stayed slightly higher. There is a dose dependence in the response of the explant to increasing levels of compressive stress (0-0.5 MPa) for 1 h. Aggrecan mRNA levels increased 2- to 3-fold at 0-0.25 MPa. At 0.5 MPa, the level of aggrecan mRNA was lower than those at 0.1 and 0.25 MPa. This dose-dependent effect suggests a reversal of the stimulatory effects of compression on aggrecan gene expression at higher loads. After 24 h of compression, the levels of aggrecan mRNA in explants subjected to any of the stress levels were not significantly different from those in control explants. The stimulatory effect of 0.1 MPa compressive stress on aggrecan mRNA levels was blocked by Rp-cAMP and U-73122, indicating the involvement of the classical signal transduction pathways in the mechanical modulation of aggrecan gene expression. The responses of link protein mRNA to compression paralleled those of aggrecan, while there was no significant change in expression of the gene for the housekeeping protein elongation factor-1 alpha. The results indicate that articular cartilage chondrocytes can respond to short-term compressive loads by transiently up-regulating expression of the aggrecan gene. The fact that long-term compression did not significantly alter aggrecan mRNA levels suggests that previously observed inhibitory effects of prolonged static compression on proteoglycan synthesis in articular cartilage may be, for the most part, mediated through mechanisms other than suppression of aggrecan mRNA levels.

Aggrecans↗

PubMed1991

Compression of foods during freeze-drying: water plasticization at the ice-dry layer interface.

The compressive mechanical properties of freeze-dried green beans show a pronounced decrease in rigidity when moisture content and/or temperature are increased. There exist several temperature and moisture combinations which give common values for mechanical properties. These combinations also give a common compressive behavior. Using this information on mechanical properties, it is possible to predict a stress-strain relationship, if given either a temperature, a moisture content, or the value of a pertinent mechanical property. It is shown that the moisture contents and temperatures that exist in the dry layer during freeze-drying result in mechanical properties that are suitable for compression of the dry layer. From studies on compression behavior during freeze-drying, it is shown that applied compressive pressure is the main determinant of final degree of compression. Increasing the compressive pressure gave a higher compression effect and gave a more rapid drying, presumably due to improved heat transfer in the compressed dry layer. From the above information, a simple method to predict compression behavior during freeze-drying was developed.

Fabaceae↗

PubMed2000

Wavelet compression on detection of brain lesions with magnetic resonance imaging.

The purpose of this report is to assess clinically acceptable compression ratios on the detection of brain lesions at magnetic resonance imaging (MRI). Four consecutive T2-weighted and the corresponding T1-weighted images obtained in 20 patients were studied for 109 anatomic sites including 50 with lesions and 59 without lesions. The images were obtained on a 1.5-T MR unit with a pixel size of 0.9 to 1.2 x 0.47 mm and a section thickness of 5 mm. The image data were compressed by wavelet-based algorithm at ratios of 20:1, 40:1, and 60:1. Three radiologists reviewed these images on an interactive workstation and rated the presence or absence of a lesion with a 50 point scale for each anatomic site. The authors also evaluated the influence of pixel size on the quality of image compression. At receiver operating characteristic (ROC) analysis, no statistically significant difference was detected at a compression ratio of 20:1. A significant difference was observed with 40:1 compressed images for one reader (P = .023), and with 60:1 for all readers (P = .001 to .012). A root mean squared error (RMSE) was higher in 0.94- x 0.94-mm pixel size images than in 0.94- x 0.47-mm pixel size images at any compression ratio, indicating compression tolerance is lower for the larger pixel size images. The RMSE, subjective image quality, and error images of 10:1 compressed 0.94- x 0.94-mm pixel size images were comparable with those of 20:1 compressed 0.94- x 0.47-mm pixel size images. Wavelet compression can be acceptable clinically at ratios as high as 20:1 for brain MR images when a pixel size at image acquisition is around 1.0 x 0.5 mm, and as high as 10:1 for those with a pixel size around 1.0 x 1.0 mm.

Algorithms↗

PubMed1994

Joint photographic experts group (JPEG) compatible data compression of mammograms.

We have developed a Joint Photographic Experts Group (JPEG) compatible image compression scheme tailored to the compression of digitized mammographic images. This includes a preprocessing step that segments the tissue area from the background, replaces the background pixels with a constant value, and applies a noise-removal filter to the tissue area. The process was tested by performing a just-noticeable difference (JND) study to determine the relationship between compression ratio and a reader's ability to discriminate between compressed and noncompressed versions of digitized mammograms. We found that at compression ratios of 15:1 and below, image-processing experts are unable to detect a difference, whereas at ratios of 60:1 and above they can identify the compressed image nearly 100% of the time. The performance of less specialized viewers was significantly lower because these viewers seemed to have difficulty in differentiating between artifact and real information at the lower and middle compression ratios. This preliminary study suggests that digitized mammograms are very amenable to compression by techniques compatible with the JPEG standard. However, this study was not designed to address the efficacy of image compression process for mammography, but is a necessary first step in optimizing the compression in anticipation of more elaborate reader performance (ROC) studies.

Algorithms↗

PubMed1999

A comparison of wavelet and Joint Photographic Experts Group lossy compression methods applied to medical images.

This presentation focuses on the quantitative comparison of three lossy compression methods applied to a variety of 12-bit medical images. One Joint Photographic Exports Group (JPEG) and two wavelet algorithms were used on a population of 60 images. The medical images were obtained in Digital Imaging and Communications in Medicine (DICOM) file format and ranged in matrix size from 256 x 256 (magnetic resonance [MR]) to 2,560 x 2,048 (computed radiography [CR], digital radiography [DR], etc). The algorithms were applied to each image at multiple levels of compression such that comparable compressed file sizes were obtained at each level. Each compressed image was then decompressed and quantitative analysis was performed to compare each compressed-then-decompressed image with its corresponding original image. The statistical measures computed were sum of absolute differences, sum of squared differences, and peak signal-to-noise ratio (PSNR). Our results verify other research studies which show that wavelet compression yields better compression quality at constant compressed file sizes compared with JPEG. The DICOM standard does not yet include wavelet as a recognized lossy compression standard. For implementers and users to adopt wavelet technology as part of their image management and communication installations, there has to be significant differences in quality and compressibility compared with JPEG to justify expensive software licenses and the introduction of proprietary elements in the standard. Our study shows that different wavelet implementations vary in their capacity to differentiate themselves from the old, established lossy JPEG.

Algorithms↗

PubMed2003

A prospective study on ultrasound-guided compression therapy or thrombin injection for treatment of iatrogenic false aneurysms in patients receiving full-dose anti-platelet therapy.

BACKGROUND: False aneurysms (FA) develop at the puncture site in up to 6% of percutaneous cardiovascular procedures. Previous management included surgery or manual compression. Recently, selective injection of thrombin has been proposed as an alternative. However, there has been no direct comparison of thrombin injection to manual compression. AIM: To study the effectiveness of manual compression compared to that of thrombin injection in patients with false aneurysms on full-dose aspirin and clopidogrel. METHODS AND PROTOCOL: All patients with a clinically suspected FA after percutaneous invasive procedures were recruited for the study. The patients were examined with color ultrasound (7.5 MHz transducer). The minimum and maximum diameters of the false aneurysm and the distance between the surface and the false aneurysm were measured online. Under local anesthesia, manual compression was applied under sonographic guidance in all patients. If compression stopped flow into the false aneurysm, manual compression was applied for a maximum of 40 min followed by compression bandage for a minimum of 12 hours. If compression failed, thrombin was injected under ultrasound guidance. RESULTS: Thirty-six patients had a FA. Their age ranged from 58 to 90 years (mean 71+/-9 years). All patients were taking aspirin (median dose 100 mg per day) and clopidogrel (median dose 75 mg per day). Additionally, 24 patients had received subcutaneous heparin (7500 to 12 500 units) or enoxaprin (0.4-1.0 ml) 3 to 12 hours before treatment. The mean width of the false aneurysm was 22.1+/-3 mm, mean length 33.6+/-35.4 mm, and mean depth 19.5+/-8.2 mm. In six patients (17%), ultrasound-guided manual compression was tolerated, succeeding after 5 to 31 minutes. Thirty patients received thrombin injections (100-1800 units, mean 880+/-470 units, median 800 units). Complete thrombosis occurred in 28 patients (93%). Surgery was performed in the other two patients. The thrombin injection was not associated with any complications. In particular, there were no peripheral vascular complications. CONCLUSION: In patients with FA taking aspirin and clopidogrel, selective thrombin injection is more effective than manual compression.

Aged↗

PubMed2002

Clinical evaluation of compression ratios using JPEG2000 on computed radiography chest images.

The efficient compression of radiographic images is of importance for improved storage and network utilization in support of picture archiving and communication systems (PACS) applications. The DICOM Working Group 4 adopted JPEG2000 as an additional compression standard in Supplement 61 over the existing JPEG. The wavelet-based JPEG2000 can achieve higher compression ratios with less distortion than the Discrete Cosine Transform (DCT)-based JPEG algorithm. However, the degradation of JPEG2000-compressed computed radiography (CR) chest images has not been tested comprehensively clinically. The authors evaluated the diagnostic quality of JPEG2000-compressed CR chest images with compression ratios from 5:1 to 200:1. An ROC (receiver operating characteristic analysis) and t test were performed to ascertain clinical performance using the JPEG2000-compressed images. The authors found that compression ratios as high as 20:1 can be utilized without affecting lesion detectability. Significant differences between the original and the compressed CR images were not recognized up to compression ratio of 50:1 within a confidence level of 99%.

Algorithms↗

PubMed2003

Quality degradation in lossy wavelet image compression.

The objective of this study was to develop a method for measuring quality degradation in lossy wavelet image compression. Quality degradation is due to denoising and edge blurring effects that cause smoothness in the compressed image. The peak Moran z histogram ratio between the reconstructed and original images is used as an index for degradation after image compression. The Moran test is applied to images randomly selected from each medical modality, computerized tomography, magnetic resonance imaging, and computed radiography and compressed using the wavelet compression at various levels. The relationship between the quality degradation and compression ratio for each image modality agrees with previous reports that showed a preference for mildly compressed images. Preliminary results show that the peak Moran z histogram ratio can be used to quantify the quality degradation in lossy image compression. The potential for this method is applications for determining the optimal compression ratio (the maximized compression without seriously degrading image quality) of an image for teleradiology.

Diagnostic Imaging↗