Altman Agreement Research Articles

Arterial blood and end-tidal concentrations of sevoflurane during the emergence from anesthesia in gynecologic patients

OBJECTIVE:The end-tidal concentration of inhalation anesthetics is a clinical indicator for predicting the emergence from anesthesia. This study was conducted to assess the relationship between arterial blood and end-tidal sevoflurane concentrations during emergence.METHODS:Thirty-two female American Society of Anesthesiologists physical status I-II patients receiving general anesthesia for elective gynecologic surgery were included. A fixed dose of 3.5% inspiratory sevoflurane in 6 L min-1 oxygen was maintained until the end of surgery. At 20 and 10 minutes before and 0, 5, 10, 15, and 20 minutes after discontinuing sevoflurane, as well as at the time of eye opening by verbal command, defined as awakening, 1 ml arterial blood was obtained to measure its sevoflurane concentration by gas chromatography. Simultaneous inspiratory and end-tidal concentrations of sevoflurane were detected by an infrared analyzer and tested by Bland–Altman agreement analysis.RESULTS:The arterial blood concentrations of sevoflurane were similar to the simultaneous end-tidal concentrations during emergence: 0.36% (0.10) and 0.36% (0.08) sevoflurane at awakening, respectively. The mean time from discontinuing sevoflurane to eye opening was 15.8 minutes (SD 2.9, range 10-26) and was significantly correlated with the duration of anesthesia (52-192 minutes) (P = 0.006) but not with the body mass index or total fentanyl dose.CONCLUSION:The mean awakening arterial blood concentration of sevoflurane was 0.36%. The time to awakening was prolonged in accordance with the anesthetic duration within 3 hours. With well-assisted ventilation during emergence, the sevoflurane end-tidal concentration was nearly equal to its arterial blood concentration, which could be a feasible predictor for awakening.

Comparison of 3.0 T magnetic resonance imaging and X-ray mammography in the measurement of ductal carcinoma in situ: A comparison with histopathology

PurposeTo determine if MRI data obtained at 3.0T can more accurately report the size of DCIS as compared to radiographic mammography, as a whole cohort and when subdivided by lesion characteristics. MethodsThirty-nine participants underwent X-ray mammography and MRI prior to breast surgery for DCIS. Longest diameter (LD) measurements were recorded for each imaging modality and compared to histopathological LD via a logarithmic transformed Bland–Altman agreement plot methodology resulting in dimensionless mean difference and 95% limits of agreement (LoA). ResultsData from 39 patients with a median age of 55 years (range 38–78 years) underwent analysis. Mastectomy was undertaken in 21 cases, while breast conserving surgery was performed in 18 subjects. Histopathological analysis revealed one low grade, nine intermediate grade, and 21 high grade lesions. The mean±standard deviation LD measurements for histopathology, X-ray mammography and MRI were 50.6±34.2mm, 30.7±23.1mm and 49.6±26.8mm respectively. Bland–Altman agreement plot analysis for the whole cohort revealed not only a smaller logarithmic mean difference between MRI and histopathology (0.086), but also narrower 95% LoA (−0.941 to 1.113) compared with X-ray mammography and histopathology (mean difference −0.658, 95% LoA −3.503 to 2.187). When the level of agreement was assessed between clinically relevant subgroups additional significant differences were noted based on grade, hormonal receptor status, invasion, necrosis, mircocalcifications and growth pattern. ConclusionMRI provides a more accurate estimation of DCIS size than X-ray mammography. MRI's superior ability was not only noted in general, but also for clinical relevant subdivisions such as grade and the presence or absence of necrosis.

Reporting standards for Bland-Altman agreement analysis in laboratory research: a cross-sectional survey of current practice.

To carry out a cross-sectional survey of the medical literature on laboratory research papers published later than 2012 and available in the common search engines (PubMed, Google Scholar) on the quality of statistical reporting of method comparison studies using Bland-Altman (B-A) analysis. Fifty clinical studies were identified which had undertaken method comparison of laboratory analytes using B-A. The reporting of B-A was evaluated using a predesigned checklist with following six items: (1) correct representation of x-axis on B-A plot, (2) representation and correct definition of limits of agreement (LOA), (3) reporting of confidence interval (CI) of LOA, (4) comparison of LOA with a priori defined clinical criteria, (5) evaluation of the pattern of the relationship between difference (y-axis) and average (x-axis) and (6) measures of repeatability. The x-axis and LOA were presented correctly in 94%, comparison with a priori clinical criteria in 74%, CI reporting in 6%, evaluation of pattern in 28% and repeatability assessment in 38% of studies. There is incomplete reporting of B-A in published clinical studies. Despite its simplicity, B-A appears not to be completely understood by researchers, reviewers and editors of journals. There appear to be differences in the reporting of B-A between laboratory medicine journals and other clinical journals. A uniform reporting of B-A method will enhance the generalizability of results.

Prospective MRI assessment for invasive lobular breast cancer. Correlation with tumour size at histopathology and influence on surgical management

To evaluate the performance of breast magnetic resonance imaging (MRI) in determining the size of invasive lobular carcinoma (ILC) compared to histopathology, and its influence on breast surgical management. Prospective evaluation was undertaken of standardized contrast-enhanced MRI images of 51 consecutive women over an 18 month period with pure ILC or with lobular features as the dominant subtype on breast core biopsy. Image interpretation was performed by one consultant radiologist (M.H.). The lesion size at MRI was compared with the size at final histopathology after surgical excision using a Bland-Altman agreement plot. Of the 51 prospectively imaged consecutive women, seven were excluded as they had diffuse ILC. The remaining 44 patients had a mean histological tumour size of 34.9 mm (range 4-77 mm). MRI underestimated tumour size in 26 (59.1%) cases. In 21 (47.7%) patients, this discrepancy was small, ranging up to 16 mm. The largest underestimation occurred in five (11.4%) cases with a difference ranging between 31 and 48 mm. Fifteen (34.1%) tumours were overestimated by MRI where the discrepancy ranged up to 22 mm. In three (6.8%) patients MRI and histological size matched. The Bland-Altman agreement plot demonstrated that in 95% of cases the size at histopathology will be between 0.36 and 2.31 times the MRI size at extremes. MRI correlated better with histopathology in tumours up to T2 (<5 cm) size leading to a change in surgical management for nine of the 44 (20.5%) patients. MRI enables surgical management decisions to be made with increased confidence in patients with ILC up to T2 size.

Comparison between the deconvolution and maximum slope 64-MDCT perfusion analysis of the esophageal cancer: Is conversion possible?

PurposeTo estimate if CT perfusion parameter values of the esophageal cancer, which were obtained with the deconvolution-based software and maximum slope algorithm are in agreement, or at least interchangeable. Methods278 esophageal tumor ROIs, derived from 35 CT perfusion studies that were performed with a 64-MDCT, were analyzed. “Slice-by-slice” and average “whole-covered-tumor-volume” analysis was performed. Tumor blood flow and blood volume were manually calculated from the arterial tumor-time–density graphs, according to the maximum slope methodology (BFms and BVms), and compared with the corresponding perfusion values, which were automatically computed by commercial deconvolution-based software (BFdeconvolution and BVdeconvolution), for the same tumor ROIs. Statistical analysis was performed using Wilcoxon matched-pairs test, paired-samples t-test, Spearman and Pearson correlation coefficients, and Bland–Altman agreement plots. ResultsBFdeconvolution (median: 74.75ml/min/100g, range, 18.00–230.5) significantly exceeded the BFms (25.39ml/min/100g, range, 7.13–96.41) (Z=−14.390, p<0.001), while BVdeconvolution (median: 5.70ml/100g, range: 2.10–15.90) descended the BVms (9.37ml/100g, range: 3.44–19.40) (Z=−13.868, p<0.001).Both pairs of perfusion measurements significantly correlated with each other: BFdeconvolution, versus BFms (rS=0.585, p<0.001), and BVdeconvolution, versus BVms (rS=0.602, p<0.001). Geometric mean BFdeconvolution/BFms ratio was 2.8 (range, 1.1–6.8), while geometric mean BVdeconvolution/BVms ratio was 0.6 (range, 0.3–1.1), within 95% limits of agreement. ConclusionsSignificantly different CT perfusion values of the esophageal cancer blood flow and blood volume were obtained by deconvolution-based and maximum slope-based algorithms, although they correlated significantly with each other. Two perfusion-measuring algorithms are not interchangeable because too wide ranges of the conversion factors were found.

Validity of the International Physical Activity Questionnaire in the Arctic

Information about physical activity (PA) in Greenland is limited, partly because of a lack of validated instruments in countries with non-Western living conditions. We modified the long form of the International Physical Activity Questionnaire (IPAQ-L) to arctic living conditions. The aim of the study was to compare IPAQ-L estimates with combined accelerometry and heart rate monitoring (ACC + HR) in a population-based study of adult Inuit in Greenland. Cross-sectional data were collected by face-to-face interview and ACC + HR monitoring among Inuit (18 yr and above) in Greenland during 2005-2010 (n = 1508). PA energy expenditure (PAEE) and time spent sedentary and on PA at moderate and vigorous intensity were derived from IPAQ-L and ACC + HR. Estimates were compared using Bland-Altman agreement analysis and Spearman correlations stratified by sex, place of residence (capital, towns, and villages), and age groups. Questionnaire-based PAEE was moderately correlated with objectively measured PAEE (r = 0.20-0.35, P < 0.01). Self-reported time spent at moderate- and vigorous-intensity PA and time spent sedentary were weakly correlated with the objective measure (r = 0.11-0.31). Agreement analyses showed relatively small median differences for all measures of PA; however, time spent at moderate-intensity PA was substantially overreported by IPAQ-L when including walking (>1.5 h·d, P < 0.001) but not when excluding walking. The IPAQ-L adapted to arctic living conditions in Greenland had a moderate level of agreement with combined accelerometry and heart rate monitoring for total PAEE at population level, but it was less valid to measure different intensities of PA and sedentary activity. Validity did not differ markedly between rural and urban communities.

Reliability of a method to conduct upper airway analysis in cone-beam computed tomography

The aim of this study was to assess the reliability of a method to measure the following upper airway dimensions: total volume (TV), the nasopharyngeal narrowest areas (NNA), and the oropharyngeal narrowest areas (ONA). The sample consisted of 60 cone-beam computed tomography (CBCT) scans, evaluated by two observers twice, using the Dolphin 3D software (Dolphin Imaging & Management solutions, Chatsworth, California, USA), which afforded image reconstruction, and measurement of the aforementioned dimensions. The data was submitted to reliability tests, by the intraclass correlation coefficient (ICC), and the Bland & Altman agreement tests, with their respective confidence intervals (CI) set at 95%. Excellent intra- and interobserver reliability values were found for all variables assessed (TV, NNA and ONA), with ICC values ranging from 0.88 to 0.99. The data demonstrated an agreement between the two assessments of each observer and between the first evaluations of both observers, thus confirming the reliability of this methodology. The results suggest that this methodology can be used in further studies to investigate upper airway dimensions (TV, NNA, and ONA), thereby contributing to the diagnosis of upper airway obstructions.

Predictive Demi-Span Equations for Estimation of Stature in Aged Mexican Americans.

To develop demi-span height predictive equations for older Mexican Americans. Cross-sectional study. Data files housed by the Sociomedical Division in the department of Community Health and Preventive Medicine at the University of Texas Medical Branch in Galveston, Texas. 1,078 (700 females, 378 males) Southwest U.S.A. community-dwelling older Mexican Americans, aged 80-102 years. Demi-span, height, weight, BMI, demi-span equivalent height (DSEH), DSEH derived BMI (DS-BMI). Bland and Altman agreement analysis on: height and DSEH; BMI and DS-BMI. Paired t-test comparing derived and actual measures by single-age units and sex. DSEH with Bassey equations (DSEHBassey) are significantly different than actual measures. DSEHBassey derived BMIs (DSBasseyBMIs) are significantly different than BMIs computed from actual measures. DSEH with Mexican equations (DSEHMexican) are not significantly different than real measures. DSEHMexican derived BMIs (DSMexicanBMIs) are not significantly different than real measures. These findings provide evidence that both DSEHBassey and DSBasseyBMIs estimates are significantly different from measured height and BMI. Both DSEHMexican and DSMexicanBMIs estimates are shown to produce similar height and BMI estimates to those obtained from real measures. .

An analysis of intraoperative versus post-operative dosimetry with CT, CT–MRI fusion and XMR for the evaluation of permanent prostate brachytherapy implants

Background and purpose To assess the agreement between intraoperative and post-operative dosimetry and to identify factors that influence dose calculations of prostate brachytherapy implants. Materials and methods Patients treated with prostate brachytherapy implants underwent post-operative CT and XMR (combined X-ray and MR) imaging. Dose–volume histograms were calculated from CT, XMR and CT–MR fusion data and compared with intraoperative values for two observers. Multiple linear regression models assessed the influences of intraoperative D90, gland oedema, gland volume, source loss and migration, and implanted activity/volume prostate on post-operative D90. Results Forty-nine patients were studied. The mean D90 differences (95% confidence limits) between intraoperative and post-operative CT, XMR and CT–MR fusion assessments were: 11 Gy (−22, 45), 18 Gy (−13, 49) and 20 Gy (−17, 58) for Observer 1; and 15 Gy (−34, 63), 13 Gy (−29, 55) and 14 Gy (−27, 54) for Observer 2. Multiple linear regression modelling showed that the observed oedema and intraoperative D90 were significant independent variables for the prediction of post-operative D90 values for both observers using all modalities. Conclusion This is the first study to report Bland–Altman agreement analysis between intraoperative and post-operative dosimetry. Agreement is poor. Post-operative dosimetry is dependent on the intraoperative D90 and the subjectively outlined gland volume.

A comparison between a new automatic system and Doppler method for obtaining ankle brachial pressures

The prevalence of peripheral arterial disease (PAD) increases with age, affecting 3% under 60 years, rising to >20% over 75 years. Whilst 40% of PAD patients are symptomatic, around 60% are asymptomatic. PAD is a reliable marker of future vascular disease such as Congestive Heart Disease (CHD) and stroke, and a substantial public health issue. In the UK around 100,000 people are diagnosed every year resulting in 60% of PAD patients dying from MI and 12% from stroke. PAD is present in ~30% of the diabetic population and considered to be a greater risk-factor than neuropathy for foot ulceration. The purpose of this study is to test the hypotheses that using the new device (Dopplex Ability), A) the ABPI test can be performed quicker than Doppler, B) obviates the need to rest the patient and C) provides results in good agreement with Doppler. The analysis methods used were Bland Altman agreement plots, equality plots and Pearson correlation.

Does fetal weight estimated by ultrasound really affect the success rate of external cephalic version?

OBJECTIVE. To determine whether fetal weight estimated by ultrasound on the day the external cephalic version (ECV) is related to the procedure's success rate. DESIGN. Retrospective cohort study. Setting. University hospital. POPULATION OR SAMPLE. Two hundred women with a singleton pregnancy undergoing an ECV attempt between March 2002 and March 2006. METHOD. Projected birthweight at delivery was calculated. Logistic regression analysis, by grams and by weight intervals, and multiple correspondence analysis were performed to determine whether or not the weight was related to the procedure's success. Specific statistical analysis was undertaken to minimize measurement bias in fetal weight estimation. MAIN OUTCOME MEASURE. Success of ECV in relation to estimated fetal weight. RESULTS. Measurement bias was ruled out because no statistically significant differences were identified with the Student's t-test (p>0.05), Bland-Altman's agreement analysis, and the interclass correlation coefficient analysis (ICC = 0.829; CI95% 0.772-0.871; p<0.01). By logistic regression analysis, a variable relation between fetal weight estimated by ultrasound and ECV success was detected, while multiple correspondence analysis suggested that variations in fetal weight are weakly related to the procedure's success or failure. No relation was identified between ECV and birthweight (p = 0.38) when the delivery took place in the same week as the version. CONCLUSIONS. Estimated fetal weight before ECV seems not to be related to the outcome of ECV.

Psychometric Properties and Cross-Cultural Adaptation of the Brazilian Quebec Back Pain Disability Scale Questionnaire

Cross-cultural translation and psychometric testing. To translate and cross-culturally adapt the Quebec Back Pain Disability Scale (QDS) to Brazilian Portuguese and to examine its validity and reliability. Current literature shows the need to adopt reliable and internationally standardized methods for the analysis of low back pain. To our knowledge, this specific questionnaire has not been translated and validated for Portuguese-speaking patients. The translation and cross-cultural adaptation of the QDS were developed in agreement with internationally recommended methodology, and the resulting product was evaluated in this study with 54 consecutive patients. Internal consistency was obtained through Cronbach's alpha; reliability was estimated through the intraclass correlation coefficient and the Bland and Altman agreement (d = mean difference). Validity was determined by correlating the scores of the Brazil-QDS with the Brazilian version of the Roland-Morris Questionnaire and Visual Analogue Pain Scale by means of the Spearman rank correlation coefficient. The internal consistency obtained was excellent (Cronbach's alpha = 0.97). Intraobserver and interobserver reliability were considered strong (ICC = 0.93-d = 0.68 and 0.96-d = 0.57, respectively). The correlation with Brazilian Roland-Morris Questionnaire and with the Visual Analogue Scale was high (r = 0.857; r = 0.758, respectively). The data showed that the process of translation and cross-cultural adaptation were successful and that the adapted instrument demonstrated excellent psychometric properties.

Abstract 2211: Left Ventricular Stroke Volume Values Measured by 2- D Echocardiographic Volumetric and Doppler-Based Methods Cannot be Used Interchangeably

The values of left ventricular stroke volume (SV) measured by Doppler and 2-D echo are frequently reported as if they were interchangeable. No systematic evaluation of the agreement between these methods has been done. To determine the agreement, correlation and reproducibility of SV values measured by 2-D echo and Doppler methods. 107 healthy subjects (mean age 59 ± 14 yrs, 59 % females), had comprehensive echocardiographic evaluation. 2-D LV volumes (2D) were measured by the biplane Simpson’s method. For Doppler, the product of the area of the LV outflow tract (LVOT) x LVOT time velocity integral (TVI), and the area of aortic annulus (AA), and the product of aortic cusp separation (ACS) x aortic TVI were used. Mixed model analysis of variance was performed and Bland Altman agreement limits, Pearson correlation and within-subject coefficient of variation and intraclass correlation coefficient were determined. The mean SV (ml/beat) measured by 2-D and Doppler methods using LVOT, AA and ACS area were: 64 ± 18, 65 ± 15, 76±14, 70 ± 16, respectively. No differences were found between LVOT and 2-D (p = 0.99), borderline between LVOT and ACS (p = 0.051) and significant differences were found between all the other methods. The within-subject coefficient of variation was 19.3% and the intraclass correlation coefficient =0.71, for all the methods indicating good reproducibility. Bland Altman 95% agreement limits for LVOT vs. 2-D were −38.0 and 38.6 ml/beat. The correlation coefficients for all 4 methods are given below. 1. In healthy subjects, although no significant differences were found between mean SV values measured by 2-D and Doppler LVOT methods, the correlation was weak and the agreement limits were large. 2. There was a modest correlation between the Doppler methods and between AA, ACS and 2-D, but the mean SV values were significantly different. 3. SV values measured by these 4 methods cannot be used interchangeably.

Radiographic assessment of the index to ring finger ratio (2D:4D) in adults

The smaller index to ring finger (2D:4D) ratio has been considered as a 'male finger pattern' and is associated with sporting ability and a number of conditions. However, the ratio may vary according to what is measured, the hand selected and the method used. This study aimed to determine: (1) which bones (phalanges, metacarpals or both) account for variation in the 2D:4D ratio; (2) whether the ratio shows right-left symmetry or relates to hand dominance; and (3) the correlation between visual classification and measured determinations of the ratio based on radiographs. Hand radiographs obtained as part of a large osteoarthritis genetic study were examined. Each hand was classified visually into three types according to the relative length of the index and ring finger: Type 1 (index longer than ring), Type 2 (index = ring) and Type 3 (index shorter than ring). For both index and ring fingers we measured (1) from base of proximal to tip of distal phalanx and (2) metacarpal length. Reproducibility of the classification and measurements were examined using kappa and intraclass correlation coefficient; symmetry between left and right hands was examined using Bland and Altman's agreement analysis; and correlation between visual classification and 2D:4D ratio data was analysed using the anova linearity test. Data were obtained from 3172 radiographs (1636 men, 1536 women; mean age 67 +/- 7.9 years, range 45-86 years). Prevalence of Type 3 hand was 61% in men and 37% in women (P < 0.001). Men had smaller 2D:4D ratios than women for phalanges (0.908 versus 0.922, P < 0.01), metacarpals (1.152 versus 1.157, P < 0.01) and the sum of phalanges plus metacarpals (1.005 versus 1.015, P < 0.01). The mean difference between right and left was -0.001 (95% limit of agreement -0.035, 0.032) for the phalangeal ratio and 0.003 (95% limit of agreement -0.051 to 0.057) for the metacarpal ratio. The 2D:4D ratio did not associate with handedness or age. There was a linear trend between the visual classification of hand type and the 2D:4D ratio data (P < 0.001). More technical difficulties (due to positioning, finger trauma, osteoarthritis) were encountered with the phalangeal ratio and visual categorization than with the metacarpal ratio: the latter could be measured in 98.7% of the study population. We concluded that measured 2D:4D ratios and visual categorization can be derived from hand radiographs. The phalanges and metacarpals both contribute to the variation in 2D:4D ratio with smaller ratios observed in men than in women. The ratio is symmetrical with only very small differences between right and left hands. Visual classification may be a useful simple tool for future epidemiological studies but is more prone to bias from positioning than direct measurement. If radiographs are used for this purpose, we recommend the metacarpal ratio with measurement of a single index hand or an average of both as it is least affected by bias from malpositioning, trauma or common joint disease.

Validez y confiabilidad del cuestionario del ENASEM para la depresión en adultos mayores

To assess the validity and reliability of a geriatric depression questionnaire used in the Mexican Health and Age Study (MHAS). The study was conducted at the Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán (INCMNSZ) clinic from May 2005 to March 2006. This depression screening nine-item questionnaire was validated using the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV-TR) (fourth revised version) and Yesavage's 15-item Geriatric Depression Scale (GDS-15) criteria. The instrument belongs to the MHAS, a prospective panel study of health and aging in Mexico. A total of 199 subjects 65 years of age and older participated in the validation process (median age= 79.5 years). MHAS questionnaire result was significantly correlated to the clinical depression diagnosis (p<0.001) and to the GDS-15 score (p<0.001). Internal consistency was adequate (alpha coefficient: 0.74). The cutoff point > or = 5/9 points yielded an 80.7% and 68.7% sensitivity and specificity respectively. The fidelity for the test retest was excellent (intra-class correlation coefficient= 0.933). Finally, the Bland and Altman agreement points indicated a difference 0.22 percent points between test retest. The MHAS questionnaire is valid and trustworthy, and allows screening in the research field for the presence of depression in the elderly.

Imaging Core Lab Comparison of Five Clinical Liver Iron MRI Methods and Biopsy for Hepatic Iron Concentration (HIC) in Sickle Cell Disease (SCD) Patients.

Introduction: HIC is a surrogate for total body iron in pts with transfusional iron overload. MRI techniques based on signal intensity ratios (SIR) or relaxation rates (R2 and R2*) are increasingly accepted as surrogates to biopsy in determining HIC. MRI techniques have been validated using data acquired on different MRI platforms, but image processing has been restricted to labs where the techniques were developed. We tested the ability of an imaging core lab to process data from 4 different MRI techniques:Gradient echo (GE) SIR (Gandon et al);Spin echo (SE) SIR (Jensen et al);R2 (Wood et al);R2* (Wood et al).R2 St. Pierre processing is proprietary and was not implemented by the core lab. The goal was to collect pilot data to test the feasibility of independent core lab assessment as well as assess inter-technique agreement and interobserver variability.Methods: Seven CICL670A0109 MRI/liver biopsy substudy pts (all at CHLA; one withdrew after baseline [BL] exam) participated in an open-label comparison of deferasirox and DFO in SCD pts. Liver biopsy (analyzed centrally at Ctre Hosp Univ, Rennes, France) was performed at BSL and 1 yr, and MRIs at BL, 6 mo and 1 yr on a 1.5 T GE CVi scanner, system 9.1. Exam consisted of localization, a total of 15 breathhold acquisitions for GE-SIR, R2* and R2 (Wood), and 30 min of free-breathing SE acquisitions for SE-SIR and R2 (St Pierre). A MnCl2 phantom (13 vials, 0–24 mM) was scanned 5x over 14 mo. De-identified DICOM images for SIRs, R2* and R2 Wood were analyzed at an imaging core lab. R2 and R2* maps were reconstructed by pixelwise fitting to a monoexponential plus an offset using custom (IDL) software. ROI selections were validated with the investigators responsible for developing the techniques (YG, PJ, JW).Results: BL biopsy HIC was 18.8±5.7 [11.7–28.3]. High HIC precluded successful HIC calculation by GE-SIR in 17/19 examinations. In contrast, SE-SIR was measurable in all studies but demonstrated a large bias compared with biopsy (Table). All three relaxation rate techniques yielded unbiased HIC assessment with acceptable agreement. Unlike previous reports, the MRI techniques agreed better among themselves than with biopsy (R=0.75–0.93), suggesting that, even with standardized collection, biopsy variability represented a major source of error in this study. Interobserver variability had means=−1.5–2.6% and SD=1.9–2.4 %. Errors introduced by different fitting algorithms had mean values of 0.5%–1.4% and SD of 1.3–3.1%. MnCl2 phantom MR values were stable over study duration (COV=3.5% [1.2–8.0]).Bland Altman Agreement and Correlation Coefficientsvs Liver Biopsyvs R2 (St Pierre)TechniqueMean, %SD, %r-valueMean, %SD, %r-valueR2, St Pierre−2.924.70.72---R2, Wood−5.024.30.75−3.714.00.93R2*, Wood−0.125.00.67−4.921.00.85SE-SIR, Jensen27.033.00.3034.648.60.75Signif bias in italConclusion: With higher HIC, R2 and R2* metrics are more generalizable than SIR metrics. Computational and observer-based errors introduced by differences in image post-processing are small compared with the errors introduced by biopsy sampling errors and intersubject variability in MRI-iron calibration.

Usefulness of Lung Perfusion Scintigraphy Before Lung Cancer Resection in Patients with Ventilatory Obstruction

The study was conducted to evaluate the efficacy of preoperative lung perfusion scintigraphy performed by planar acquisition and single-photon emission computed tomography (SPECT) in predicting postoperative pulmonary function of patients with resectable lung cancer and obstructive ventilatory defect. The study enrolled 39 patients (mean age, 67 +/- 2.1 years). All patients underwent preoperative and postoperative pulmonary function tests. Cut-off values for postoperative forced expiratory volume in 1 second (FEV1) were 65% of the predicted value for pneumonectomy and 45% for lobectomy. A semiquantitative analysis of planar and SPECT lung perfusion scintigraphy images was performed preoperatively to estimate postoperative predicted FEV1 (FEV1ppo). Relationships between FEV1ppo and measured postoperative FEV1 were tested by the Pearson correlation and Bland Altman agreement tests. Twenty-eight lobectomies and 11 pneumonectomies were performed. The FEV1ppo estimated by mean planar lung scintigraphy was 1.85 +/- 0.38 L, with a Pearson correlation coefficient to the measured FEV1 of 0.8632 (p < 0.001). The mean FEV1ppo estimated by SPECT was 1.78 +/- 0.31 L, with a Pearson coefficient to the measured FEV1 of 0.8527 (p < 0.001). Both values showed a more significant correlation with postoperative measured FEV1 after lobectomy (p < 0.001) than after pneumonectomy (p = 0.045). The Bland Altman test confirmed satisfactory agreement of FEV1ppo estimated by both planar lung scintigraphy and SPECT with FEV1 measured by spirometry. Both planar lung scintigraphy and SPECT can accurately predict postoperative FEV1 and can therefore be considered reliable tools in establishing operability of patients with lung cancer and ventilatory obstruction.

P-5-641 - Orbital masses approaches

To assess the agreement between intraoperative and post-operative dosimetry and to identify factors that influence dose calculations of prostate brachytherapy implants.Patients treated with prostate brachytherapy implants underwent post-operative CT and XMR (combined X-ray and MR) imaging. Dose–volume histograms were calculated from CT, XMR and CT–MR fusion data and compared with intraoperative values for two observers. Multiple linear regression models assessed the influences of intraoperative D90, gland oedema, gland volume, source loss and migration, and implanted activity/volume prostate on post-operative D90.Forty-nine patients were studied. The mean D90 differences (95% confidence limits) between intraoperative and post-operative CT, XMR and CT–MR fusion assessments were: 11 Gy (−22, 45), 18 Gy (−13, 49) and 20 Gy (−17, 58) for Observer 1; and 15 Gy (−34, 63), 13 Gy (−29, 55) and 14 Gy (−27, 54) for Observer 2. Multiple linear regression modelling showed that the observed oedema and intraoperative D90 were significant independent variables for the prediction of post-operative D90 values for both observers using all modalities.This is the first study to report Bland–Altman agreement analysis between intraoperative and post-operative dosimetry. Agreement is poor. Post-operative dosimetry is dependent on the intraoperative D90 and the subjectively outlined gland volume.