Search PubMed⌕ Search

Biomedical subjects

A Gottschalk

Publications and source records attributed to A Gottschalk.

At least 55 records · Page 3Linked to original sources
PubMed1999

Silent meniscal abnormalities in athletes: magnetic resonance imaging of asymptomatic competitive gymnasts.

BACKGROUND: Magnetic resonance imaging (MRI) produces exceptionally detailed images of the intra-articular structures of the knee. Recognising the range of MRI appearances within a normal population is therefore necessary in order to avoid attributing a greater significance to these than is clinically justified. OBJECTIVE: To compare MRI appearances in asymptomatic gymnasts with those in a less active population in order to identify findings that may be seen in the absence of significant pathology and thereby aid the clinical management of this athletic group. METHODS: MR images were obtained from 24 knees of asymptomatic competitive American collegiate gymnasts aged 18-22. The menisci were evaluated according to established grading criteria, and compared with a group of controls matched for age and sex. RESULTS: Grade 3 intrameniscal signal abnormalities are considered to be highly correlated with meniscal tears. When compared with control group, the experimental group of gymnasts had a significantly different distribution (p<0.001) of grade 3 intrameniscal signal changes, preferentially involving the lateral meniscus. The overall incidence of grade 3 changes (13%) in gymnasts was not, however, significantly different from the incidence in the controls. CONCLUSIONS: A knowledge of these MRI appearances is important when evaluating the lateral menisci within this group of athletes to prevent unnecessary treatment or intervention. This is particularly pertinent when the imaging findings do not closely correlate with the site of symptoms.

Adolescent↗
PubMed1999

Reassessment of pulmonary angiography for the diagnosis of pulmonary embolism: relation of interpreter agreement to the order of the involved pulmonary arterial branch.

PURPOSE: To reassess the validity of conventional pulmonary angiography in the diagnosis of pulmonary embolism (PE) in main, lobar, segmental, and subsegmental pulmonary arteries. MATERIALS AND METHODS: Data are from examinations of 375 patients with angiographically diagnosed PE who participated in the Prospective Investigation of Pulmonary Embolism Diagnosis. The average co-positivity of readings of the pulmonary angiograms was evaluated in relation to the order of the largest pulmonary artery that showed PE. RESULTS: Among 217 patients whose angiograms showed PE in main or lobar pulmonary arteries, as well as in smaller orders of arteries, there was an average co-positivity of 98% (95% Cl = 96%, 98%). Among 136 patients whose pulmonary angiograms showed PE in segmental or subsegmental pulmonary arteries but not in larger orders of arteries, the average co-positivity was 90% (95% Cl = 85%, 95%). Among 22 patients with PE limited to the subsegmental arteries, the average co-positivity was 66% (95% Cl = 46%, 86%). CONCLUSION: Conventional pulmonary angiography is not precise for the diagnosis of PE limited to subsegmental arteries. To evaluate subsegmental arteries, techniques that improve the visualization of PE in small arteries should be used.

Angiography↗
PubMed1998

Preemptive epidural analgesia and recovery from radical prostatectomy: a randomized controlled trial.

CONTEXT: Preemptive analgesia can decrease the sensitization of the central nervous system that would ordinarily amplify subsequent nociceptive input, but a clear demonstration of its clinical efficacy is necessary for it to become a routine component of acute pain therapy. OBJECTIVE: To determine the impact of preemptive epidural analgesia on postoperative pain and other clinically important outcome variables after radical retropubic prostatectomy. DESIGN AND SETTING: A block randomized double-blind clinical trial lasting 20 months at a single academic medical center. PATIENTS: A total of 100 generally healthy and neurologically intact patients scheduled for radical retropubic prostatectomy for the treatment of prostate cancer in whom an epidural catheter for treating postoperative pain was to be placed prior to the induction of general anesthesia. INTERVENTIONS: Epidural bupivacaine, epidural fentanyl, or no epidural drug was administered prior to induction of anesthesia and throughout the entire operation, followed by aggressive postoperative epidural analgesia for all patients. MAIN OUTCOME MEASURES: Daily pain scores during hospitalization and pain scores obtained 3.5, 5.5, and 9.5 weeks after hospital discharge. RESULTS: The patients who received epidural fentanyl or bupivacaine prior to surgical incision (preemptive analgesia) experienced 33% less pain while hospitalized (P=.007). Pain scores in those receiving preemptive analgesia were significantly lower at 9.5 weeks (P=.02), but were not significantly different at 3.5 or 5.5 weeks. At 9.5 weeks, 32 (86%) of 37 patients receiving preemptive analgesia were pain-free compared with 9 (47%) of 19 control patients (P=.004). Patients receiving preemptive analgesia were more active 3.5 weeks after surgery (P=.01), but not at 5.5 or 9.5 weeks. CONCLUSIONS: Even in the presence of aggressive postoperative pain management, preemptive epidural analgesia significantly decreases postoperative pain during hospitalization and long after discharge, and is associated with increased activity levels after discharge.

Aged↗
PubMed1998

Cardiac output measurement by transpulmonary versus conventional thermodilution technique in intensive care patients after coronary artery bypass grafting.

OBJECTIVE: The aim of the present study was to evaluate the correlation, accuracy, and precision of transpulmonary thermodilution cardiac output (CO) measurement. For this purpose, this technique was compared with the clinical gold standard, the CO measurement by pulmonary artery catheter in patients after coronary artery bypass grafting (CABG). DESIGN: A prospective clinical study. SETTING: A university medical center. PARTICIPANTS: Seventy-five patients in an intensive care unit (ICU) after CABG. INTERVENTIONS: Standard (SCO) and transpulmonary thermodilution CO measurement (TPCO) measurements were simultaneously performed in triplicate by central venous injection of cooled saline solution. All variables were recorded at five different time points of measurement during weaning from mechanical ventilation. MEASUREMENTS AND MAIN RESULTS: CO measurements yielded 375 data pairs. SCO ranged from 2.0 to 10.2 L/min, and TPCO from 1.3 to 10.6 L/min. During the entire observation period, TPCO measurements tended to yield relatively high values, whereas SCO measurements resulted in lower values. Correlation between TPCO and SCO measurements was significant (r = 0.73; p < 0.05), accompanied by an accuracy with a bias of 0.456 L/min (7.3%) and a precision of 1.156 L/min (18.5%). CONCLUSION: In most patients, TPCO measurement will not replace the conventional technique by pulmonary artery catheter, but in some patients it offers an attractive, reliable, and safe method to determine CO.

Aged↗
PubMed1998

Cbf5p, a potential pseudouridine synthase, and Nhp2p, a putative RNA-binding protein, are present together with Gar1p in all H BOX/ACA-motif snoRNPs and constitute a common bipartite structure.

The eukaryotic nucleolus contains a large number of small nucleolar RNAs (snoRNAs) that are involved in preribosomal RNA (pre-rRNA) processing. The H box/ACA-motif (H/ACA) class of snoRNAs has recently been demonstrated to function as guide RNAs targeting specific uridines in the pre-rRNA for pseudouridine (psi) synthesis. To characterize the protein components of this class of snoRNPs, we have purified the snR42 and snR30 snoRNP complexes by anti-m3G-immunoaffinity and Mono-Q chromatography of Saccharomyces cerevisiae extracts. Sequence analysis of the individual polypeptides demonstrated that the three proteins Gar1p, Nhp2p, and Cbf5p are common to both the snR30 and snR42 complexes. Nhp2p is a highly basic protein that belongs to a family of putative RNA-binding proteins. Cbf5p has recently been demonstrated to be involved in ribosome biogenesis and also shows striking homology with known prokaryotic psi synthases. The presence of Cbf5p, a putative psi synthase in each H/ACA snoRNP suggests that this class of RNPs functions as individual modification enzymes. Immunoprecipitation studies using either anti-Cbf5p antibodies or a hemagglutinin-tagged Nhp2p demonstrated that both proteins are associated with all H/ACA-motif snoRNPs. In vivo depletion of Nhp2p results in a reduction in the steady-state levels of all H/ACA snoRNAs. Electron microscopy of purified snR42 and snR30 particles revealed that these two snoRNPs possess a similar bipartite structure that we propose to be a major structural determining principle for all H/ACA snoRNPs.

Amino Acid Sequence↗
PubMed1998

A comprehensive biochemical and genetic analysis of the yeast U1 snRNP reveals five novel proteins.

The U1 snRNP is essential for recognition of the pre-mRNA 5'-splice site and the subsequent assembly of the spliceosome. Yeast U1 snRNP is considerably more complex than its metazoan counterpart, which suggests possible differences between yeast and metazoa in early splicing events. We have comprehensively analyzed the composition of yeast U1 snRNPs using a combination of biochemical, mass spectrometric, and genetic methods. We demonstrate the specific association of four novel U1 snRNP proteins, Snu71p, Snu65p, Nam8p, and Snu56p, that have no known metazoan homologues. A fifth protein, Npl3p, is an abundant cellular component that reproducibly co-purifies with the U1 snRNP, but its association is salt-sensitive. Therefore, we are unable to establish conclusively whether it binds specifically to the U1 snRNP. Interestingly, Nam8p and Npl3p were previously assigned functions in (pre-m)RNA-metabolism; however, so far, no association with U1 snRNP has been demonstrated or proposed. We also show that the yeast SmB protein is a U1 snRNP component. Yeast U1 snRNP therefore contains 16 different proteins, including seven snRNP core proteins, three homologues of the metazoan U1 snRNP-specific proteins, and six yeast-specific U1 snRNP proteins. We have simultaneously continued the characterization of additional mutants isolated in a synthetic lethal (MUD) screen for genes that functionally cooperate with U1 snRNA. Consistent with the biochemical results, mud10, mud15, and mud16 are alleles of SNU56, NAM8, and SNU65, respectively. mud10 and mud15 affect the in vivo splicing efficiency of noncanonical introns. Moreover, mud10p strongly affects the in vitro formation of splicing complexes, and extracts from the mud15 strain contain a U1 snRNP that migrates aberrantly on native gels. Finally, we show that Nam8p/Mud15p contributes to the stability of U1 snRNP.

Amino Acid Sequence↗
PubMed1997

Identification of the proteins of the yeast U1 small nuclear ribonucleoprotein complex by mass spectrometry.

Here we report the rapid identification of the proteins of the spliceosomal U1 small nuclear ribonucleoprotein (snRNP) from the yeast Saccharomyces cerevisiae by searching mass spectrometric data in genomic sequence databases. The U1 snRNP, containing a histidine-tagged 70K protein, was isolated from cell extracts by anti m3G-cap immunoaffinity and subsequent nickel nitrilotriacetic acid chromatography. A U1 snRNP fraction containing 20 proteins was obtained. Further purification by glycerol gradient centrifugation identified nine U1 snRNP specific and six common proteins. The U1 snRNP proteins were partially sequenced by nanoelectrospray mass spectrometry, and their genes were identified in the data base via multiple peptide sequence tags. Apart from the already known common proteins D1, D3, F, and G, the D2 and E homologs were also identified. The same six common proteins were detected in core U2 snRNP, which was purified and analyzed separately. The biochemical association of these six proteins with yeast snRNPs is shown here for the first time. Intriguingly, the Sm B/B' homolog was not detected. In addition to the well characterized yeast U1 specific proteins [U1-70K (Snp1p), U1-A (Mud1p), Prp39p, and Prp40p] the homolog of the U1-C protein was identified together with four additional novel U1 specific proteins, which are not found in mammalian U1. This is the first time that the components of a multiprotein complex from an organism with a sequenced genome have been characterized by mass spectrometry. The technique should be applicable to any protein complex that can be biochemically purified from an organism whose genome is known.

Amino Acid Sequence↗
PubMed1997

Oncologic imaging: interactions of nuclear medicine with CT and MRI using the bone scan as a model.

There are many radionuclides currently used in oncologic imaging including technetium 99m diphosphonates, gallium 67, thallium 201, technetium 99m sestamibi, and others. The specific interactions of each of these agents with computed tomography (CT) and magnetic resonance imaging (MRI) are extensive. The radionuclide bone scan using 99mTc diphosphonate is the most frequently performed nuclear medicine examination in oncologic imaging. The bone scan can be used as a model to generalize the interactions of nuclear medicine with CT and MRI. The applications for the bone scan and many other nuclear medicine procedures in oncologic imaging include evaluating for metastases, assessing the response to therapy, and guiding radiation therapy planning. Bone scan findings that are equivocal for metastases can be evaluated with other imaging modalities. Areas of abnormal uptake in the axial skeleton can be evaluated with CT or MRI, whereas those in the appendicular skeleton can be evaluated with plain radiographs, followed by CT or MRI if necessary. The bone scan is valuable in oncologic imaging because of its high sensitivity for lesion detection, its ease in whole body imaging, and its low cost. The major disadvantage of the bone scan is that it lacks fine anatomic detail, which is of particular importance in the cancer patient with local back pain, radiculopathy, or myelopathy. Because local back pain with or without radiculopathy is the earliest symptom of spinal cord compression in 90% of patients, an MRI is the study of choice because of its exquisite depiction of anatomy. A myelogram followed by a postmyelogram CT can be performed if there are contraindications to an MRI. The basic principle of high sensitivity for lesion detection and ease in whole body imaging provided by nuclear medicine and fine anatomic detail provided by CT and MRI can be applied also to the use of other radionuclides in oncologic imaging.

Bone Neoplasms↗
PubMed1997

Capnography during jet ventilation for laryngoscopy.

Jet ventilation is often used during laryngoscopy to permit improved visualization of the larynx and to eliminate a potentially flammable endotracheal tube when laser surgery of the airway is performed. Observation of chest wall movement and blood gas analysis are the usual standards for assessing the adequacy of ventilation during jet ventilation. It is reasonable to hypothesize that measurement of end-tidal CO2 concentrations during jet ventilation can be used to assess the adequacy of ventilation during jet ventilation. To test this hypothesis, end-tidal CO2 concentrations were determined during mechanical ventilation through an endotracheal tube and during jet ventilation. At the time that each end-tidal measurement was obtained, a sample of arterial blood was also obtained for later blood gas analysis. For both mechanical ventilation and jet ventilation, well defined relationships between end-tidal CO2 and arterial CO2 tensions were obtained. However, the relationships are distinct: the difference in arterial to end-tidal CO2 tension during supraglottic jet ventilation at a conventional respiratory rate was found to be 13.4 +/- 6.8 mm Hg (mean +/- SD) compared with 5.7 +/- 5.2 mm Hg obtained during conventional ventilation through an endotracheal tube.

Capnography↗
PubMed1996

Effects of continuous (CPAP) and bi-level positive airway pressure (BiPAP) on extravascular lung water after extubation of the trachea in patients following coronary artery bypass grafting.

OBJECTIVE: To evaluate the effects of continuous positive airway pressure (CPAP) and bi-level positive airway pressure (Bi-PAP) on extravascular lung water during weaning from mechanical ventilation in patients following coronary artery bypass grafting. DESIGN: Prospective, randomized clinical study. SETTING: Intensive care unit at a university hospital. PATIENTS: Seventy-five patients following coronary artery bypass grafting. INTERVENTIONS: After extubation of the trachea, patients were treated for 30 min with CPAP via face mask (n = 25), with nasal BiPAP (n = 25), or with oxygen administration via nasal cannula combined with routine chest physiotherapy (RCP) for 10 min (n = 25). MEASUREMENTS AND RESULTS: Extravascular lung water (EVLW), pulmonary blood volume index (PBVI) and cardiac index (CI) were obtained during mechanical ventilation (T1), T-piece breathing (T2), interventions (T3), spontaneous breathing 60 min (T4) and 90 min (T5) after extubation of the trachea using a combined dye-thermal dilution method. Changing from mechanical ventilation to T-piece breathing did not show any significant differences in EVLW between the three groups, but a significant increase in PBVI from 155 +/- 5 ml/m2 to 170 +/- 4 ml/m2 could be observed in all groups (p < 0.05). After extubation of the trachea and treatment with BiPAP. PBVI decreased significantly to 134 +/- 6 ml/m2 (p < 0.05). After treatment with CPAP or BiPAP, EVLW did not change significantly in these groups (5.5 +/- 0.3 ml/kg vs 5.0 +/- 0.4 ml/kg and 5.1 +/- 0.4 ml/kg vs 5.7 +/- 0.4 ml/kg). In the RCP-treated group, however, EVLW increased significantly from 5.8 +/- 0.3 ml/kg to 7.1 +/- 0.4 ml/kg (p < 0.05). Sixty and 90 min after extubation, EVLW stayed at a significantly higher level in the RCP-treated group (7.5 +/- 0.5 ml/kg and 7.4 +/- 0.5 ml/kg) than in the CPAP-(5.6 +/- 0.3 ml/kg and 5.9 +/- 0.4 ml/kg) or BiPAP-treated groups (5.2 +/- 0.4 ml/kg and 5.2 +/- 0.4 ml/kg). No significant differences in CI could be observed within the three groups during the time period from mechanical ventilation to 90 min after extubation of the trachea. CONCLUSIONS: Mask CPAP and nasal BiPAP after extubation of the trachea prevent the increase in extravascular lung water during weaning from mechanical ventilation. This effect is seen for at least 1 h after the discontinuation of CPAP or BiPAP treatment. Further studies have to evaluate the clinical relevance of this phenomenon.

Aged↗
PubMed1996

The early years with Hal Anger.

In the course of your day, when you interpret or count a radioimmunoassay or a sample of blood or body fluid, you will probably use a variant of the well counter invented by Hal O. Anger in the early 1950s. If you obtain or read a patient image, it probably came from some type of his gamma camera. If yoy do or see a single photon emission computed tomography study, Hal Anger showed the feasibility. Even if you are working with positrons, some of the early imaging work was done by devices Hal Anger invented. This article deals primarily with the years I spent with Hal, 1962 to 1964. I was fortunate to have the opportunity to spend this time with him when he had just completed the development of his 11-in gamma camera, the first multipurpose camera suitable for diverse clinical examinations. In retrospect, it is easy to see why Hal was honored by the Society of Nuclear Medicine as one of its pioneers and why he was the first recipient of the Ben Cassen Prize. However, it was not always clear that Hal's creative road would lead to such deserved distinction. I have tried to portray the beginnings of this journey to the best of my recollections.

History, 20th Century↗
PubMed1996

Scintigraphic lung scans and clinical assessment in critically ill patients with suspected acute pulmonary embolism.

PURPOSE: The purpose of this investigation was to evaluate the diagnostic accuracy of radionuclide scintigraphic lung scans and clinical assessment in critically ill patients with suspected acute pulmonary embolism. MATERIALS AND METHODS: Critically ill patients were defined as follows: (1) patients who were hypoxemic on room air, and not given ventilatory support (n = 89); (2) patients given ventilatory support (n = 46); and (3) patients in ICUs, but not given ventilatory support (n = 85), and hypotensive patients who were not hypoxemic or given ventilatory support (n = 3). Comparisons were made with patients who had none of these characteristics of critically ill patients (n = 627). Data are from the Prospective Investigation of Pulmonary Embolism Diagnosis. RESULTS: The sensitivities, specificities, and positive predictive values of high probability lungs scans among each of the four categories of critically ill patients were not statistically significantly lower than values in noncritically ill patients. The positive predictive values of the clinical assessments did not differ to a statistically significant extent from noncritically ill patients. Clinical assessment, when concordant with the lung scan interpretation, usually increased the positive predictive value for pulmonary embolism. CONCLUSION: Scintigraphic lung scans and clinical assessment retain their diagnostic value even in critically ill patients.

Acute Disease↗
PubMed1996

Can pulmonary angiography be limited to the most suspicious side if the contralateral side appears normal on the ventilation/perfusion lung scan? Data from PIOPED. Prospective Investigation of Pulmonary Embolism Diagnosis.

PURPOSE: The purpose of this investigation was to determine the frequency of pulmonary embolism (PE) in a single lung that showed a normal ventilation/perfusion (V/Q) lung scan when the V/Q scan on the contralateral side was interpreted as non-high-probability for PE. METHODS: Data are from the national collaborative study Prospective Investigation of Pulmonary Embolism Diagnosis (PIOPED). PE was diagnosed or excluded in all lungs by pulmonary angiography. RESULTS: Single lungs with no V/Q abnormalities, when the V/Q scan on the contralateral side was interpreted as non-high-probability for PE, showed PE in 2 of 19 (11%) (95% confidence interval [CI], 1 to 33%). If PE was excluded by angiography on the side of the abnormal V/Q scan, then PE on the side of the normal V/Q scan was shown in only 1 of 19 (5%) (95% CI, 0 to 26%). CONCLUSION: A normal V/Q scan in a single lung, when the contralateral lung was interpreted as non-high-probability for PE, did not completely exclude PE on the apparently normal side. In such lungs, the probability of PE was in the range of low-probability interpretations. If the pulmonary angiogram showed no PE on the side of the abnormal V/Q scan, the probability of PE on the side of the normal V/Q scan satisfied the definition of very low probability for PE. This observation in patients undergoing pulmonary angiography may assist in determining whether the pulmonary angiogram should be bilateral.

Confidence Intervals↗
PubMed1996

Pulmonary embolism among patients with a nearly normal ventilation/perfusion lung scan.

BACKGROUND: Among patients with nearly normal ventilation/perfusion (V/Q) lung scans in the Prospective Investigation of Pulmonary Embolism Diagnosis (PIOPED), pulmonary embolism (PE) was diagnosed more frequently in those who underwent pulmonary angiography than in those in whom PE was diagnosed on the basis of an adverse outcome while receiving no anticoagulant therapy. This may suggest that an adverse outcome is not apparent in patients with PE of such mild severity that the V/Q scan is nearly normal. If this were the case, patients with mild PE might not require treatment. PURPOSE: The purpose of this investigation was to evaluate patients in PIOPED with nearly normal-V/Q lung scans. The V/Q scans and clinical characteristics of those in whom PE was diagnosed or excluded by pulmonary angiography (angiography group) were compared with those in whom PE was diagnosed or excluded by the presence or absence of an adverse outcome while not receiving anticoagulant therapy (outcome group). If the characteristics were the same, it would suggest that some patients with mild PE do well without treatment. If the characteristics were different, it would indicate that there is no evidence from these data that mild PE need not be treated. METHODS: Data from PIOPED were evaluated from patients with suspected acute PE who had V/Q scans interpreted as nearly normal. There were 75 patients in the angiography group and 90 patients in the outcome group. Patients with entirely normal V/Q scans were excluded. RESULTS: PE was more frequent in the angiography group than in the outcome group, 8 of 75 (11%) vs 0 of 90 (0%) (p < 0.01). In patients with nearly normal V/Q scans who were in the outcome group in comparison to the angiography group, the V/Q scan showed fewer mismatched segmental perfusion defects, a lower percentage of low-probability V/Q interpretations by one of the two V/Q readers (compared with very low or normal probability), and a generally lower clinical assessment. CONCLUSION: The observed lower frequency of PE in the outcome group in comparison to the angiography group can be attributed to a lower likelihood of PE in this group of patients with nearly normal V/Q scans in comparison to those who underwent pulmonary angiography. There is no evidence from these data that occasional patients with nearly normal V/Q scans who have PE do not require treatment.

Acute Disease↗
PubMed1996

Patient stratification by cardiopulmonary status in the diagnosis of pulmonary embolism.

UNLABELLED: The purpose of this investigation is to provide further evidence in support of the interpretation of ventilation/perfusion (V/Q) lung scans on the basis of criteria dependent on whether or not the patient has prior cardiopulmonary disease (CPD). METHODS: Data are from the collaborative PIOPED study. We evaluated the original PIOPED database to obtain the consensus probability estimates of pulmonary embolism (PE) among patients stratified according to the presence or absence of prior CPD. RESULTS: Among patients with no prior CPD, nuclear physicians consistently underestimated the probability of PE (odds ratio 1.62, 95% confidence interval 1.10-2.38, p = .014). CONCLUSION: Past experience guided nuclear physicians into correctly estimating the probability of acute PE on V/Q scans of patients with prior CPD. The criteria they subjectively used was inadequate for estimating the probability of acute PE in patients with no prior CPD. Different criteria, therefore, apply to the interpretation of V/Q scans in these two groups.

Heart Diseases↗
PubMed1996

Evaluation of individual criteria for low probability interpretation of ventilation-perfusion lung scans.

UNLABELLED: The purpose of this investigation was to identify characteristics or combinations of characteristics of the ventilation-perfusion (V/Q) scan in patients with suspected acute pulmonary embolism (PE) can be used for a "very low probability" interpretation ( < 10% positive predictive value). METHODS: Data were culled from individual lungs of 532 patients in the randomized arm of the Prospective Investigation of Pulmonary Embolism Diagnosis (PIOPED) study and 205 patients in the referred arm. All patients had a < 20% consensus probability estimate of PE based on V/Q scan results, and all underwent pulmonary angiography. RESULTS: Nonsegmental perfusion abnormalities, perfusion defects smaller than opacities on the chest radiograph, a combination of these types of perfusion abnormalities, and matched V/Q abnormalities in two or three zones of a single lung had a positive predictive value < 10%. These criteria can therefore be used for a very low probability interpretation. A matched V/Q defect in only one zone of the lung had a positive predictive value greater than 10% and is not a criterion for low probability. Perfusion defects associated with small pleural effusions (obliteration of the costophrenic angle) had a positive predictive value of 25%-33%, depending on the group studied, and are a criterion for intermediate probability. CONCLUSION: Criteria appropriate for a very low probability ( < 10% positive predictive value) interpretation of V/Q scans in patients with suspected acute PE have been identified.

Evaluation Studies as Topic↗