Diagnostic Performance Parameters Research Articles

A Prospective Study on the Added Value of Pulsed Arterial Spin-Labeling and Apparent Diffusion Coefficients in the Grading of Gliomas

The purpose of this study was to determine whether qualitative and quantitative measures obtained with pulsed arterial spin-labeling (PASL) and apparent diffusion coefficients (ADC) improve glioma grading compared with conventional MR images. We prospectively performed 2 qualitative consensus reviews in 33 suspected gliomas: 1) conventional MR images alone and 2) conventional MR images with PASL and ADC. To calculate the diagnostic performance parameters of PASL and ADC, we used a qualitative scoring system on the basis of the tumor perfusion signal intensity (sTP) and visual ADC scoring (sADC). We then analyzed quantitative regions of interest and calculated the ratio of the maximum tumor perfusion signal intensity (rTPmax) and the minimum ADC value (mADC). Two observers diagnosed accurate tumor grades in 23 of 33 (70%) lesions in the first review and in 29 of 33 (88%) lesions in the second review. The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) for determining a glioma grading by using combined sTP and sADC scoring were 90.9, 90.9, 95.2, and 83.3%, respectively. Statistical analysis gave a threshold value of 1.24 for rTPmax and 0.98 x 10(-3) mm/s(2) for mADC to provide a sensitivity, specificity, PPV, and NPV of 95.5, 81.8, 91.3, and 90.1% and 90.9, 81.8, 90.9, and 81.8%, respectively. The receiver operator characteristic curve analyses showed no significant difference between the quantitative and combined qualitative parameters. PASL and ADC significantly improve the diagnostic accuracy of glioma grading compared with conventional imaging.

Prostate Cancer: Body-Array versus Endorectal Coil MR Imaging at 3 T—Comparison of Image Quality, Localization, and Staging Performance

To prospectively compare image quality and accuracy of prostate cancer localization and staging with body-array coil (BAC) versus endorectal coil (ERC) T2-weighted magnetic resonance (MR) imaging at 3 T, with histopathologic findings as the reference standard. After institutional review board approval and written informed consent, 46 men underwent 3-T T2-weighted MR imaging with a BAC (voxel size, 0.43 x 0.43 x 4.00 mm) and an ERC (voxel size, 0.26 x 0.26 x 2.50 mm) before radical prostatectomy. Four radiologists independently evaluated data sets obtained with the BAC and ERC separately. Ten image quality characteristics related to prostate cancer localization and staging were assigned scores. Prostate cancer presence was recorded with a five-point probability scale in each of 14 segments that included the whole prostate. Disease stage was classified as organ-confined or locally advanced with a five-point probability scale. Whole-mount-section histopathologic examination was the reference standard. Areas under the receiver operating characteristic curve (AUCs) and diagnostic performance parameters were determined. A difference with a P value of less than .05 was considered significant. Forty-six patients (mean age, 61 years) were included for analysis. Significantly more motion artifacts were present with ERC imaging (P<.001). All other image quality characteristics improved significantly (P<.001) with ERC imaging. With ERC imaging, the AUC for localization of prostate cancer was significantly increased from 0.62 to 0.68 (P<.001). ERC imaging significantly increased the AUCs for staging, and sensitivity for detection of locally advanced disease by experienced readers was increased from 7% (one of 15) to a range of 73% (11 of 15) to 80% (12 of 15) (P<.05), whereas a high specificity of 97% (30 of 31) to 100% (31 of 31) was maintained. Extracapsular extension as small as 0.5 mm at histopathologic examination could be accurately detected only with ERC imaging. Image quality and localization improved significantly with ERC imaging compared with BAC imaging. For experienced radiologists, the staging performance was significantly better with ERC imaging.

Standardized Threshold Approach Using Three-Dimensional Proton Magnetic Resonance Spectroscopic Imaging in Prostate Cancer Localization of the Entire Prostate

We sought to determine the localization accuracy using 3-dimensional (3D) proton magnetic resonance spectroscopic imaging (MRSI) of the entire prostate with a standardized thresholds approach in prostate cancer patients. In a prospective study, 32 consecutive patients were examined. Mean age and prostate specific antigen level were 61 years and 7.8 ng/mL, respectively. Median biopsy Gleason score was 6. T2-weighted MRI and 3D MRSI of the entire prostate were performed. Three readers recorded the location of suspicious peripheral zone and central gland cancer nodules on a standardized division of the prostate (14 regions of interest [ROI]) using a standardized thresholds approach. The degree of diagnostic confidence for each ROI was recorded on a 5-point scale. Reconstructed whole-mount section histopathology was the standard of reference. The sensitivity, specificity, positive, and negative predictive value, overall accuracy and interobserver agreement were calculated. Areas under the ROI-based receiver operating characteristic curve (AUC) and diagnostic performance parameters were determined. The standardized thresholds approach had an accuracy of 81% and an AUC of 0.85-0.86 for differentiation between benign and malignant ROIs in the peripheral zone and an accuracy of 87% and an AUC of 0.86-0.91 for this differentiation in the central gland, respectively. Specificities of 81% to 88% were achieved with accompanying sensitivities of 75% to 92% for both peripheral zone and central gland, respectively. Moderate to near-perfect interobserver agreement was demonstrated (kappa=0.42-0.91). Our data indicate that a standardized zone-specific threshold approach in MRSI of the prostate is able to prospectively differentiate between benign and malignant tissues in the peripheral zone and the central gland with good accuracy and interobserver agreement.

A comparison of the diagnostic performance of systematic versus ultrasound-guided biopsies of prostate cancer

Transrectal ultrasound (TRUS) is an important tool for urologists and radiologists in the detection of prostate cancer. Various TRUS-guided biopsy techniques are applied in clinical practice. Frequently, only the detection rates achieved with these methods are compared. Other diagnostic performance parameters, particularly the specificity and negative predictive value, are seldom compared. After extensive assessment of the available literature, this review describes the methods of TRUS-guided biopsy for prostate cancer detection. A distinction was made between systematic biopsies and biopsies that target a perceived (hypoechoic or Doppler-enhancing) lesion on imaging. Subsequently, the diagnostic performance (sensitivity, specificity, positive and negative predictive values, accuracies) was compared between these techniques. Imaging-guided biopsy showed better diagnostic performance than systematic biopsy with higher sensitivity. The combinations of sensitivity and specificity were highest for colour Doppler and contrast-enhanced targeted biopsy. Studies targeting hypoechoic lesions had relatively high sensitivity, but specificity was low. Presently however, with widespread prostate-specific antigen screening, fewer prostate cancers are hypoechoic, and the value of targeting hypoechoic lesions has diminished. Performing colour or contrast-enhanced Doppler biopsy or adding these techniques to systematic biopsies improves diagnostic performance, particularly by increasing sensitivity.

Home blood pressure self-monitoring: diagnostic performance in white-coat hypertension

To determine the diagnostic performance of home blood pressure self-monitoring in white-coat hypertension using a 3-day reading program. One hundred and ninety nontreated patients recently diagnosed with mild-moderate hypertension, selected consecutively at four primary healthcare centers in the city of Barcelona, were included. Each patient underwent morning and night home blood pressure self-monitoring with readings in triplicate for three consecutive days, followed by 24-h ambulatory blood pressure monitoring. The normality cut-off point value for home blood pressure self-monitoring and daytime ambulatory blood pressure monitoring was 135/85 mmHg. Sixty-three patients were diagnosed with white-coat hypertension with home blood pressure self-monitoring (34.8%; 95% confidence interval: 27.9-42.2) and 74 with ambulatory blood pressure monitoring (41.6%; 95% confidence interval: 33.7-48.4). No statistically significant differences were observed between home blood pressure self-monitoring values and those of diurnal ambulatory blood pressure monitoring [137.4 (14.3)/82.1 (8.3) mmHg vs. 134.8 (11.3)/81.3 (9.5) mmHg]. Home blood pressure self-monitoring diagnostic performance parameters were sensitivity 50.0% (95% confidence interval: 38.3-61.7), specificity 75.7% (95% confidence interval: 66.3-83.2), positive and negative predictive values 58.7% (95% confidence interval: 45.6-70.8) and 68.6% (95% confidence interval: 59.4-76.7), respectively, and positive and negative probability coefficients 2.05 and 0.66, respectively. Analysis of different normality cut-off points using a receiver operating characteristic curve failed to produce significant improvement in the diagnostic performance of home blood pressure self-monitoring. The diagnostic accuracy of a 3-day home blood pressure self-monitoring reading program in white-coat hypertension was poor. Ambulatory blood pressure monitoring continues to be the test of choice for this indication.

An in vitro Comparison between Two Methods of Electrical Resistance Measurement for Occlusal Caries Detection

Because of different measurement techniques and the easier design of the CRM prototype, this in vitro study aimed to compare the diagnostic performance and reproducibility of two electrical methods (Electronic Caries Monitor III, ECM and Cariometer 800, CRM) for occlusal caries detection, and to evaluate the effect of staining/discoloration of fissures on diagnostic performance. Hundred and seventeen third molars with no apparent occlusal cavitation were selected. Six examiners inspected all specimens independently, using the CRM, and a subgroup of 4 using the ECM. Histological validation using a stereomicroscope was performed after hemisectioning. Intra- and interexaminer reproducibility was assessed by Lin’s concordance correlation coefficient (CCC) and Bland and Altman analysis. Diagnostic performance parameters included sensitivity (SE), specificity (SP) and area under the ROC curve (A_z). The CCC yielded an intra- and interexaminer reproducibility of 0.69/0.62 (ECM) and of 0.79/0.74 (CRM). The mean intra- and interexaminer 95% range of measurements (range between Bland and Altman limits of agreement) given in percentages of the instrument reading were 67%/65% for the ECM and 28%/33% for the CRM. A_z at the D3–4 level was 0.74 (ECM) and 0.78 (CRM). The CRM showed at least equivalent diagnostic performance to the ECM. However, improvement is still desirable. Diagnostic performance appeared to be enhanced in discolored lesions; however, this may be related to sample lesion distribution characteristics.

A comparison of the diagnostic performance of systematic versus ultrasound-guided biopsies of prostate cancer

Transrectal ultrasound (TRUS) is an important tool for urologists and radiologists in the detection of prostate cancer. Various TRUS-guided biopsy techniques are applied in clinical practice. Frequently, only the detection rates achieved with these methods are compared. Other diagnostic performance parameters, particularly the specificity and negative predictive value, are seldom compared. After extensive assessment of the available literature, this review describes the methods of TRUS-guided biopsy for prostate cancer detection. A distinction was made between systematic biopsies and biopsies that target a perceived (hypoechoic or Doppler-enhancing) lesion on imaging. Subsequently, the diagnostic performance (sensitivity, specificity, positive and negative predictive values, accuracies) was compared between these techniques. Imaging-guided biopsy showed better diagnostic performance than systematic biopsy with higher sensitivity. The combinations of sensitivity and specificity were highest for colour Doppler and contrast-enhanced targeted biopsy. Studies targeting hypoechoic lesions had relatively high sensitivity, but specificity was low. Presently however, with widespread prostate-specific antigen screening, fewer prostate cancers are hypoechoic, and the value of targeting hypoechoic lesions has diminished. Performing colour or contrast-enhanced Doppler biopsy or adding these techniques to systematic biopsies improves diagnostic performance, particularly by increasing sensitivity.

Adaptation of revised Brief PHQ (Brief-PHQ-r) for diagnosis of depression, panic disorder and somatoform disorder in primary healthcare settings

Objective:The aim of this study was to determine the diagnostic accuracy of the Turkish version of the revised Brief Patient Health Questionnaire (Brief PHQ-r) in depression, panic disorder and somatoform disorder, in primary care settings.Methods:This was a cross-sectional study with blinded psychiatric evaluation. The study was conducted at three sites which provide primary health services. Total number of the participants was 1556. Of these, 1387 comprised the analysis population. Diagnoses of depression, panic disorder and somatoform disorder made according to the patient's responses to the questions on Brief PHQ-r form were compared with the diagnoses made by psychiatrists using DSM-W.Results:Diagnostic performance parameters of Brief PHQ-r were calculated. Main results are as follows: for any diagnosis k = 0.567, sensitivity 79.0%, specificity 82.9%; for major/minor depressive disorder k = 0.536, sensitivity 76.0%, specificity 85.3%; for panic disorder k = 0.640, sensitivity 74.4%, specificity 98.4% and for somatoform disorder k = 0.476, sensitivity 61.9% and specificity 92.5%.Conclusions:Diagnostic performance of Brief PHQ-r was found to be quite good in the diagnosis of major/minor depressive disorder, panic disorder and somatoform disorder, in primary healthcare settings. We recommend its use in routine clinical practice in order to help primary healthcare physicians, and also infield surveys on psychiatric disorders. Qnt] Psych Clin Pract 2004; 8: 11–18)

Pulmonary Nodule Detection and Visual Search: P45 and P104 Monochrome Versus Color Monitor Displays

Rationale and Objectives The faceplate of a cathode-ray tube (CRT) display monitor is covered on the vacuum side with a phosphor screen. The different phosphors that can be used for this screen have distinctly different physical properties that can affect the noise properties of the display. Differences in noise affect the signal-to-noise ratio and, hence, may affect diagnostic performance. This study evaluated observer performance and visual search parameters in the detection of pulmonary nodules, comparing two monochrome CRT monitors with different phosphors (P45 and P104) and a color CRT monitor. Materials and Methods The receiver operating characteristic paradigm was used to evaluate observer performance with a series of radiographic chest images containing solitary pulmonary nodules. Eye position was recorded as the observers searched the images on each type of monitor. Results Observer performance, as indicated by the area under the receiver operating characteristic curve and compared by means of an analysis of variance test, was best for the P45 monitor, next best for the P104 monitor, and worst for the color monitor. All differences were statistically significant. Eye-position parameters were also affected by monitor type. The time required to fixate the lesion and overall search times were longest with the color monitor. Conclusion The type of phosphor used in the CRT monitor faceplate can affect diagnostic performance and visual search parameters. Care should be taken in the selection of monitors for use in clinical radiology.

The efficacy of hormone assays in the differential diagnosis of amenorrhea and menopause.

The differential diagnosis of menopause and amenorrhea is currently based on the assay of circulating follicle stimulating hormone, luteinising hormone, and estradiol. The diagnostic performance of the three hormone assays, both as single and combined tests, was evaluated considering as reference data the results from 300 subjects for either condition, and assuming menopause-amenorrhea prevalence ratios corresponding to 1 and 10. In the calculation an "allocation" scheme was adopted, and the uncertainty associated with the diagnostic performance parameters was accounted for. The results obtained clearly demonstrate that the addition of a test for luteinising hormone or estradiol (or both) to the testing for follicle stimulating hormone is not justified in terms of improvement of the diagnostic information.

Validation of a diagnostic scoring system (Ohmann score) in acute appendicitis

A diagnostic scoring system, recently published by Ohmann et al. in this journal, was validated by analyzing the clinicopathological data of a consecutive series of 2,359 patients, admitted for suspicion of acute appendicitis. The results of the scoring system were compared to the results of clinical evaluation by junior (provisional) and senior surgeons (final clinical diagnosis). To assess the diagnostic ability of the score, the accuracy and positive predictive value were defined as the major diagnostic performance parameters; the rate of theoretical negative laparotomies and that of diagnostic errors served as the major procedural performance parameters. Of 2,359 patients admitted for suspected acute appendicitis, 662 were proven to have acute appendicitis by histology, for a prevalence of 28%. The overall sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of the provisional clinical diagnosis were 0.50, 0.94, 0.77, 0.83, and 0.82; 0.93, for the score 0.63, 0.93, 0.77, 0.86 and 0.84, and for the final clinical diagnosis 0.90, 0.94, 0.85, 0.96, and 0.93, respectively. Of the main diagnostic performance parameter, the accuracy of the score was significantly better than that of provisional clinical diagnosis (P < 0.05, chi 2 test). The score yielded a rate of negative appendecomies and laparotomies of 14.3 and 12.3%. With respect to the rate of overlooked cases of acute apendicitis, the score demonstrated a superior performance, with only 6 cases missed (0.9%). However, the number of patients with acute appendicitis, including those with perforated disease, who were not identified by the score, was almost four times that of the final clinical diagnosis (245 vs 63). With regard to the main procedural performance parameter, the score resulted in a significantly smaller number of diagnostic errors than the provisional clinical investigator (P < 0.05, chi 2 test). The results of this study indicate that the diagnostic scoring system might be helpful when experienced investigators or additional diagnostic modalities such as ultrasonography are not available. It may therefore be of value in the preclinical evaluation of patients with suspected acute appendicitis and may be instrumental as a quality control tool and in clinical guidelines.

Diagnostic performance of Food and Drug Administration–cleared serologic assays for natural rubber latex–specific IgE antibody

Background: In the absence of Food and Drug Administration–approved natural rubber latex skin testing reagents, latex-specific IgE antibody immunoassays are used in the diagnosis of latex allergy. Comparative diagnostic performance of these tests has not been definitively determined. Objective: We sought to study the predictive value of available Food and Drug Administration (510K)–cleared latex-specific IgE antibody immunoassays in the diagnosis of latex allergy. Methods: Subjects (n = 312) were classified as having a positive (n = 117) or a negative (n = 195) latex allergy history (Hx) or having a positive (n = 131) or a negative (n = 181) puncture skin test (PST) response (Greer reagent). The 14 subjects with a negative Hx and a positive PST response had negative responses to glove provocation testing and thus were considered sensitized but asymptomatic. Sera from 22 subjects were split to evaluate intra-assay variation. All 334 coded sera were analyzed for latex-specific IgE antibodies in the Diagnostic Products Corporation microplate AlaSTAT, Hycor HY-TEC EIA System, and Pharmacia-UpJohn CAP System. Variance and diagnostic performance parameters of each test were computed with 95% confidence intervals in relation to the subjects’ Hx and PST status. Results: Intra-assay concordance of split sera results was 96.0% for all 3 assays, with coefficients of variation of less than 25% and between-assay coefficients of variation of less than 21%. The diagnostic performance of the CAP and AlaSTAT assays were equivalent in comparison with PST results: sensitivity, CAP 76.3% and ALASTAT 73.3% and specificity, CAP 96.7% and AlaSTAT 97.2% ( P = NS). The HY-TEC assay was more sensitive (91.6%) and less specific (73.3%) than the CAP and AlaSTAT assays ( P < .001). From 9% to 25% of the sera were discordant, being positive in at least 1, but not all 3, assays. Conclusion: The CAP and AlaSTAT assays produce 24% and 27% of false-negative results, respectively, whereas the HY-TEC produces 27% of false-positive results when compared with the PST. (J Allergy Clin Immunol 1999;103:925-30.)

Diagnostic Performance of Helical CT Angiography in Trauma to Large Arteries of the Extremities

The purpose of this work was to assess the performance of helical CT angiography (CTA) in the diagnosis of injuries to large arteries of the extremities. We performed helical CTA on 45 consecutive patients referred for conventional angiography for evaluation of suspected arterial injuries after sustaining trauma to the extremities (13 upper, 32 lower). Two radiologists interpreted the helical CTA studies independently. Diagnostic performance parameters evaluated included sensitivity, specificity, receiver operating characteristic (ROC) curves, and interobserver agreement (kappa statistics). Conventional angiography was used as the standard of reference for determination of final diagnoses. Forty-three of 45 patients (96%) had diagnostic helical CTA examinations. Final diagnoses in these 43 patients were arterial occlusion (n = 7), partial obstruction (n = 3), pseudoaneurysm (n = 5), arteriovenous fistula (n = 1), pseudoaneurysm and arteriovenous fistula (n = 3), and normal findings (n = 24). Sensitivity and specificity were 90% [95% confidence interval (CI), 80-99] and 100% (95% CI, 99-100), respectively, for Reader 1 and 100% (95% CI, 99-100) and 100% (95% CI, 99-100), respectively, for Reader 2. ROC curve analysis revealed high diagnostic performance, with areas under the curve of >0.9 for both readers. Interobserver agreement was 0.9. The diagnostic performance of helical CTA for detection of major injuries of large arteries of the extremities is high.

Methods of measuring the performance of ultrasonic pulse-echo diagnostic equipment.

<h2>Abstract</h2> Methods are outlined whereby the main diagnostic performance parameters exhibited by ultrasonic pulse-echo equipment may be measured and reported. Particular aspects of performance that are considered are: acoustic frequency, echo detection capability, gain characteristics, display characteristics, geometrical resolution and geometrical alignment accuracy. Specifically excluded from consideration is the measurement of acoustic output of the equipment, since it is intended that this subject will be dealt with separately elsewhere.

Bronchography

<h3>Objective</h3> This study aims to investigate the accuracy and validity of the Australasian Triage Scale (ATS) as a tool to identify and manage in a timely manner the deteriorating patient with severe sepsis. <h3>Methods</h3> This was a prospective observational study conducted in five sites of adult patients. Keywords and physiological vital signs data from triage documentation were analysed for the ‘identified’ status compared with confirmed diagnosis of severe sepsis after admission to the intensive care unit. The primary outcome is the accuracy and validity of the ATS Triage scale categories to identify a prespecified severe sepsis population at triage. Secondary outcome measures included time compliance, antimicrobial administration and mortality prediction. Statistical analysis included parameters of diagnostic performance. Adjusted multivariate logistic regression analysis was applied to mortality prediction. <h3>Results</h3> Of 1022 patients meeting the criteria for severe sepsis, 995 were triaged through the emergency department, 164 with shock. Only 53% (n=534) were identified at triage. The overall sensitivity of the ATS to identify severe sepsis was 71%. ATS 3 was the most accurate (likelihood ratio positive, 2.45, positive predictive value 0.73) and ATS 2 the most valid (area under the curve 0.567) category. Identified cases were more likely to survive (OR 0.81, 95% CI 0.697 to 0.94, p&lt;0.007). The strongest bias-adjusted predictors of mortality were circulatory compromise variable (1.78, 95% CI 1.34 to 1.41, p&lt;0.001), lactate &gt;4 (OR 1.63, 95% CI 1.10 to 2.89, p&lt;0.001) and ATS 1 category (OR 1.55, 95% CI 1.09 to 2.35, p&lt;0.005). <h3>Conclusions</h3> The ATS and its categories is a sensitive and moderately accurate and valid tool for identifying severe sepsis in a predetermined group, but lacks clinical efficacy and safety without further education or quality improvement strategies targeted to the identification of severe sepsis.