Contrast-enhanced MR enterography as a stand-alone tool to evaluate Crohn's disease in a paediatric population.

AIM: To assess the performance of contrast-enhanced T1-weighted magnetic resonance imaging (MRI) alone in the evaluation of Crohn's disease in comparison to all magnetic resonance enterography (MRE) imaging sequences together in an attempt to suggest limitation of the number of overall unenhanced sequences need for the follow-up evaluation. MATERIALS AND METHODS: Twenty-five paediatric patients (mean age 14.1 ± 3.7 years, male = 12, female = 13) underwent MRE at 1.5 T for evaluation of Crohn's disease. Two radiologists reviewed only contrast-enhanced T1-weighted images in consensus on the first session. Whole images including unenhanced (steady-state free precession, single-shot fast spin-echo (HASTE), fat-suppressed T2-weighted) and contrast-enhanced T1-weighted sequences were reviewed in consensus during the second session with a 1 month interval, which was used as a reference standard. The readers evaluated the presence or absence of disease in 10 bowel segments in each patient. For the abnormal bowel segments, the readers then evaluated for active versus inactive disease and for the presence or absence of abscess. Sensitivity, specificity, and overall accuracy were calculated for detecting active inflammation. RESULTS: There were 53/250 bowel segments with active inflammation using the reference standard imaging method. The sensitivity, specificity, and accuracy for diagnosing active inflammation using contrast-enhanced images alone were 83.3%, 86.9%, and 84.9%. In five of the false-positive cases of detecting abscess from contrast-enhanced imaging alone, absence of abscesses was confirmed on the non-fat-suppressed HASTE images. CONCLUSION: The number of MRE sequences in paediatric Crohn's patients can be decreased while maintaining diagnostic accuracy using contrast-enhanced T1 and non-fat-suppressed HASTE images.

Pancreatic cancer: lack of association between apparent diffusion coefficient values and adverse pathological features.

AIM: To identify retrospectively potential associations between apparent diffusion coefficient (ADC) values of pancreatic adenocarcinoma and tumour grade as well as other pathological features, using histopathological assessment from the Whipple procedure as the reference standard. MATERIALS AND METHODS: Thirty patients with pancreatic adenocarcinoma underwent magnetic resonance imaging (MRI) including diffusion-weighted imaging with b-values of 0 and 500 s/mm(2) before the Whipple procedure. Two radiologists independently recorded the ADC values of the tumour and benign pancreas for all cases. ADC values were compared with histopathological findings following the Whipple procedure. RESULTS: The intra-class correlation coefficient was 0.689 for benign pancreas and 0.695 for tumours, indicating good inter-reader agreement for ADC values. The mean ADC value was significantly lower in tumours than in benign pancreas for both readers (reader 1: 1.74 ± 0.34 × 10(-3) mm(2)/s versus 2.08 ± 0.48 × 10(-3) mm(2)/s, respectively, p = 0.006; reader 2: 1.69 ± 0.41 × 10(-3) mm(2)/s versus 2.11 ± 0.54 × 10(-3) mm(2)/s, respectively, p < 0.001). However, there was no significant difference in mean ADC between poorly and well/moderately differentiated tumours for either reader (reader 1: 1.69 ± 0.36 × 10(-3) mm(2)/s versus 1.78 ± 0.33 × 10(-3) mm(2)/s, respectively, p = 0.491; reader 2: 1.62 ± 0.33 × 10(-3) mm(2)/s versus 1.75 ± 0.49 × 10(-3) mm(2)/s, respectively, p = 0.405). The area under the curve (AUC) for differentiation of poorly and well/moderately differentiated tumours was 0.611 and 0.596 for readers 1 and 2, respectively, and was not significantly better than an AUC of 0.500 for either reader (p ≥ 0.306). In addition, ADC was not significantly different for either reader between tumours with stage T3 versus stage T1/T2, between tumours with and without metastatic peri-pancreatic lymph nodes, or between tumours located in the pancreatic head versus other pancreatic regions (p ≥ 0.413). CONCLUSION: No associations between ADC values of pancreatic adenocarcinoma and tumour grade or other adverse pathological features were observed.

Impact of delay after biopsy and post-biopsy haemorrhage on prostate cancer tumour detection using multi-parametric MRI: a multi-reader study.

AIM: To assess impact of haemorrhage and delay after biopsy on prostate tumour detection using multi-parametric (MP) magnetic resonance imaging (MRI) assessment. MATERIALS AND METHODS: Forty-four patients underwent prostate MRI at 1.5 T using a pelvic phased-array coil, including T1-weighted imaging (T1WI), T2-weighted imaging (T2WI), diffusion-weighted imaging (DWI), and dynamic contrast-enhanced (DCE) imaging, before prostatectomy. Three radiologists independently reviewed images during four sessions [T2WI, DWI, DCE, and all parameters combined (MP-MRI)] to assess for tumour in each sextant. In a separate session, readers reviewed T1WI to score the extent of haemorrhage per sextant. Accuracy was assessed using logistic regression for correlated data. RESULTS: There was no significant difference in accuracy between readers for any session (p ≥ 0.166), and results were averaged across the three readers for remaining comparisons. Accuracy was significantly greater for MP-MRI than for any parameter alone (p ≤ 0.020). For T2WI alone, there was a trend toward decreased sensitivity in sextants with extensive haemorrhage (p = 0.072). However, accuracy, sensitivity, and specificity were otherwise similar for sextants with and without extensive haemorrhage for all sessions (p = 0.192-0.934). No session showed a significant improvement in accuracy, sensitivity, or specificity in cases with delay after biopsy of over 4 weeks compared with shorter delay. CONCLUSION: Extensive haemorrhage and short delay after biopsy did not negatively impact accuracy for tumour detection using MP-MRI. Further studies using MP-MRI protocols and interpretation schemes from other institutions are required to confirm these observations.

Streptavidin blotting: a sensitive technique to study cell surface proteins; application to investigate autophosphorylation and endocytosis of biotin-labeled insulin receptors.

Covalent attachment of biotin provides a useful method to label cell surface proteins. Subsequent to biotinylation, the protein can be purified by immunoprecipitation with a specific antibody, followed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. After transfer to a membrane by electroblotting, the biotinylated protein can be detected by probing with labeled streptavidin. This technique has been used to investigate recombinant human insulin receptors expressed on the surface of murine NIH-3T3 cells. Biotinylation of the extracellular domain with an impermeant reagent did not impair the ability of an antibody directed against an epitope in the intracellular domain to immunoprecipitate insulin receptors. In contrast, biotinylation reduced the avidity of a polyclonal antibody directed against the extracellular domain of the receptor. Nevertheless, by increasing the concentration of the antireceptor antibody, it was possible to successfully immunoprecipitate the biotinylated receptor. Furthermore, biotinylated receptors retained the ability to bind insulin and undergo insulin-stimulated autophosphorylation and internalization. The use of enzyme-labeled streptavidin enables the use of chemiluminescence techniques to detect the receptors, thus obviating the need to employ radioactivity. Just as the technique is useful to study cell surface insulin receptors, it can be adapted to investigate other cell surface receptors and proteins.

Estimation of myocardial infarct size by electrocardiographic and radionuclide techniques.

The Western Washington Intravenous Streptokinase in Acute Myocardial Infarction Trial was a randomized, experimental, multicenter clinical study comparing intravenous streptokinase therapy to conventional therapy of acute myocardial infarction. Myocardial infarct size was estimated by spatial vectorcardiography in 93 patients in the treatment group and 80 patients in the control group eight weeks post MI. The estimated infarct size for the treated group was smaller: 16 +/- 10% MI vs. 20 +/- 9% MI for the control group, P = 0.01. Four independent techniques to estimate infarct size were prospectively compared within the same day: Cowan's spatial VCG; the Selvestor/Wagner QRS score; 99m technetium synchronized ejection fractions and 201-Thallium Tomography. There was strong correlation between the two ECG techniques (r = 0.88) and between the two radionuclide techniques (r = 0.77). Statistically significant correlations (P = 0.0001) were described, respectively, among the four techniques, but the correlations were not clinically strong between electrocardiographic and radionuclide techniques: IAD vs. EF, r = -0.41; IAD vs. 201-Tl, r = 0.50; QRS Score vs. EF, r = -0.49; QRS Score vs. 201-Tl, r = 0.58.

A comprehensive estimation of acute myocardial infarct size using enzymatic, electrocardiographic and mechanical methods.

This prospective study compares the estimated size of acute myocardial infarction (AMI) by cumulative serum creatine kinase isoenzyme MB (CK-MB), Selvester QRS score, and 2-dimensional (2-D) echocardiographic dyssynergy of the left ventricle in 63 consecutive patients with their first anterior (n = 31) or inferior AMI (n = 32). The correlations among these parameters were good for patients with anterior AMI (r = 0.74 to 0.78, standard error of the estimate = 29 to 33%) but only fair for those with inferior AMI (r = 0.35 to 0.47, standard error of the estimate = 38 to 73%). Based on previous autopsy studies, estimates of CK-MB and QRS score were then converted to percent of infarcted left ventricle. Linear regression analyses between mean percent AMI size by cumulative CK-MB plus QRS score vs the number of dyssynergic segments by 2-D echocardiography were used to develop a comprehensive formula for estimating AMI size by a combination of all 3 techniques. Thus, a formula is proposed that may optimally estimate AMI size derived from leakage of cytosolic enzymes, changes in the sequence of myocardial depolarization, and irregularities of left ventricular contraction.

Enhancement of an old diagnostic tool, the standard 12-lead ECG.

The standard 12-lead electrocardiogram (ECG) has long been a reliable clinical tool for diagnosis of myocardial infarction (MI). Minutes may be crucial in the decision regarding urgent interventions for the salvage of severely ischemic myocardium during an acute MI. Besides history and physical findings the ECG may be the only clinical tool immediately available in deciding to initiate acute coronary thrombolysis or balloon angioplasty. Most of the newer techniques are difficult to perform and time consuming, and thus are not immediately available. Recent studies have indicated that there may be important information revealed by the amplitude and direction of the ST-T vectors on the admission ECG that will correlate with the final infarct size which evolves during the next few hours. The Selvester QRS scoring system, based on computer simulations of the human heart activation sequence, uses quantitative information in the 12-lead ECG to estimate the size of an MI. This system, which can be automated, has been examined for specificity in a large database of normals, and validated in a series of comprehensive post-mortem studies, and in other clinical estimates of prognosis and MI size. The QRS scoring system is limited by its inability to differentiate between small MIs and normal myocardium and by the confounding effects on the ECG of ventricular hypertrophy, conduction defects, and multiple MIs. Current studies are expected to overcome most of these limitations. Computer technology further augments the clinical utility of the ECG by providing unique assessment of a patient from individualized demographic and historical characteristics.(ABSTRACT TRUNCATED AT 250 WORDS)

Identification of the optimal electrocardiographic leads for detecting acute epicardial injury in acute myocardial infarction.

Current coronary care electrocardiographic (ECG) monitoring techniques are aimed at detection of cardiac arrhythmias rather than myocardial ischemia. However, in patients with acute myocardial infarction (AMI) who undergo reperfusion therapy, monitoring ST-segment deviation could provide an early noninvasive indicator of coronary artery reocclusion. In this study, the admission 12-lead ECGs of patients with initial AMI were used to propose optimal lead locations for ST-segment monitoring. The study population was selected from consecutive Duke University Medical Center admissions during 1965 to 1981 who met the following inclusion criteria: chest pain for no more than 8 hours, initial AMI documented by ECG and 3 of 4 enzyme criteria, greater than or equal to 0.1 mV (1 mV = 10 mm) of ST elevation in at least 1 of the standard 12 leads (not aVR) on admission ECG, and no ECG evidence of conduction disturbances, ventricular hypertrophy or tachycardia. ST-segment deviation was quantified; AMI location was assigned based on the lead with maximal deviation. Of the 80 patients who had an inferior AMI, lead III was both the most frequent location for ST elevation (94%) and the most common site with maximal ST deviation. Lead V2 had the highest incidence of ST-segment depression (60%). In the 68 patients who had an anterior AMI, lead V2 had the highest frequency of ST elevation (99%). Leads V2 and V3 were the most common sites of maximal elevation. Thus, for monitoring ST deviation, leads III and V2 may be superior to leads II and V1, which are commonly used in arrhythmia monitoring.(ABSTRACT TRUNCATED AT 250 WORDS)

Relation between electrocardiographic and enzymatic methods of estimating acute myocardial infarct size.

The extent of initial acute myocardial infarction (AMI) and subsequent patient prognosis were studied using 2 independent indicators of AMI size. Two inexpensive, readily available techniques, the complete Selvester QRS score from the standard 12-lead electrocardiogram and the peak value of the isoenzyme MB of creatine kinase (CK-MB), were evaluated in 125 patients with initial AMI. The overall correlation between peak CK-MB and QRS score was fair (0.57), with marked difference according to anterior (0.72) or inferior (0.35) location. The prognostic capabilities of each measurement varied. Peak CK-MB provided significant information concerning hospital morbidity or early mortality (within 30 days) for both anterior (chi 2 = 9.83) and inferior (chi 2 = 7.68) AMI locations; however, the QRS score was significant only for anterior AMI (chi 2 = 9.50). For total 24-month mortality, the QRS score alone provided the most information (chi 2 = 10.0, p = 0.0016), which was not improved with the addition of CK-MB (chi 2 = 0.07, p = 0.79). This study shows a good relation between these 2 independent estimates of AMI size for patients with anterior AMI location. Both QRS and CK-MB results are significantly related to early morbidity and mortality; however, only the QRS score is related to total 24-month prognosis.

Identification of electrocardiographic criteria for diagnosis of right ventricular hypertrophy due to mitral stenosis.

Current electrocardiographic (ECG) criteria for diagnosing right ventricular hypertrophy (RVH) have low sensitivity. In this study maximally specific and sensitive ECG criteria for RVH due to mitral stenosis (MS) were developed that incorporated the principles derived from spatial changes in the QRS complex observed on the vectorcardiogram and any existent ECG criteria that supplement the diagnostic capability of the criteria derived from the vectorcardiogram. The standard 12-lead electrocardiograms of a control group of 500 consecutively selected subjects with 50 women and 50 men in each decade between ages 20 and 69 years were compared with the electrocardiograms of a study population of 50 patients with RVH due to MS. Inclusion criteria were a diagnosis of MS by catheterization, normal coronary arteriographic and left ventriculographic findings and no other valvular abnormalities. It was hypothesized that patients with RVH resulting from MS would have QRS forces that are maximally anterior (A) and rightward (R) and minimally posterolateral (PL); thus, the A + R - PL value in the study group would be greater than that in the control group. The subsequently derived formula criterion (A + R - PL greater than or equal to 0.7 mV) and 2 additional criteria, R less than or equal to 0.2 mV in lead I and P less than 0.25 mV in leads II, III, aVF, V1 or V2, were tested in both groups. The specificity and sensitivity of each individual criterion was determined; when combined, the criteria yielded 94% specificity and 64% sensitivity. Moderate to severe RVH due to MS was detected in two-thirds of the patients using the proposed criteria.

Evaluation of a QRS scoring system for estimating myocardial infarct size. V. Specificity and method of application of the complete system.

The specificity of a previously developed 57-criteria/32-point QRS scoring system for estimating myocardial infarct (MI) size is evaluated in an extensive control population and the method of application of this system for determining a QRS score from a standard 12-lead electrocardiogram is described. Points are accumulated from Q- and R-wave durations, R- and S-wave amplitudes, R/Q- or R/S-amplitude ratios and the presence of R-wave notching, with each point representing approximately 3% of the left ventricle. The subjects were selected because of the minimal likelihood of their having had myocardial infarcts or other sources of QRS modification. There were 500 consecutively selected normal Caucasian subjects, aged 20 to 69 years, with 50 women and 50 men in each of the 5 decades. Specificity for the 57 individual criteria ranged from 89 to 100%. Fifty-one criteria met the required standard of at least 95% specificity; of the 6 that failed, 3 were successfully modified to achieve this standard and 3 were eliminated. In the resultant 54-criteria/32-point complete system, the total population, as well as both women and men, required more than 3 points to attain at least 95% specificity. Subjects in each of the 5 decades met the specificity standard either at or below the level of more than 3 points. The point score at which 95% or greater specificity was attained for the 10 age/sex subsets varied.(ABSTRACT TRUNCATED AT 250 WORDS)

Evaluation of a QRS scoring system for estimating myocardial infarct size. IV. Correlation with quantitative anatomic findings for posterolateral infarcts.

This study correlated the location and size of posterolateral myocardial infarcts (MIs) measured anatomically with that estimated by quantitative criteria derived from the standard 12-lead ECG. Twenty patients were studied who had autopsy-proved, single, posterolateral MIs and no confounding factors of ventricular hypertrophy or bundle branch block in their ECG. Left ventricular anatomic MI size ranged from 1 to 46%. No patient had a greater than or equal to 0.04-second Q wave in any electrocardiographic lead and only 55% had a 0.03-second Q wave. A 29-point, simplified QRS scoring system consisting of 37 weighted criteria was applied to the ECG. Points were scored by the ECG in 85% of the patients (range 1 to 8 points). MI was indicated by a wide variety of QRS criteria; 19 of the 37 criteria from 8 different electrocardiographic leads were met. The correlation coefficient between MI size measured anatomically and that estimated by the QRS score was 0.72. Each point represented approximately 4% MI of the left ventricular wall.

Evaluation of serial QRS changes during acute inferior myocardial infarction using a QRS scoring system.

The evolution of changes in the QRS complex during the initial 3 days after the onset of an initial inferior myocardial infarction (MI) was studied in 82 consecutive patients. Each patient's standard 12-lead electrocardiogram was assigned points (a QRS score) according to the absolute duration of the Q and R waves and the amplitude ratios of R-to-Q and R-to-S waves. This QRS score has been demonstrated to correlate (r = 0.74) with the anatomic extent of single inferior MI. By this system, 43 patients (53% of the study group) had an initial electrocardiogram that registered a score of 0 and developed QRS points only after admission. The QRS scores of 18 additional patients (22% of the study group) changed after admission. Forty-nine score changes were noted on Day 2 and 18 on Day 3. All of these changes resulted in an increased QRS score. Alteration of the QRS complex during initial inferior MI evolves over 2 to 3 days in many patients. There is a distinct pattern to this evolution, which results in sequential increases in a QRS score based upon electrocardiographic indicators of the extent of myocardial necrosis. This QRS scoring system might be applied to evaluate clinically interventions aimed at limiting the extent of necrosis in patients with initial acute inferior MI.