Acquired left bundle branch block in an asymptomatic fighter pilot: a case report

This report describes a case of acquired left bundle branch block (LBBB) in an asymptomatic F/A-18 fighter pilot of the Royal Australian Air Force. The previously fit and healthy pilot was found to have LBBB on routine electrocardiographic screening prior to his annual aircrew medical. He was completely asymptomatic, and the only potential etiological factor was a short-lived acute gastrointestinal infectious illness some 4 mo previously. The pilot was extensively investigated with the full range of available diagnostic procedures, including coronary angiography and cardiac biopsy. No cause was determined for his LBBB pattern, and he was assessed as having normal cardiovascular function. The aeromedical disposition of this aviator and the issues involved in determining fitness to fly in such a case are discussed. The importance of thorough clinical investigation and appropriate follow-up are highlighted.     

Standard provocative manoeuvres in patients with and without left bundle branch block studied with myocardial SPECT

BACKGROUND: The objective of this study was to determine the prevalence of anterior and septal defects in patients with left bundle branch block (LBBB), and to assess the diagnostic accuracy of myocardial single photon emission computed tomography (SPECT) with technetium compounds in patients with and without LBBB using standard provocative manoeuvres. METHODS: Five hundred and nine consecutive patients (456 without LBBB and 53 with LBBB) without previous infarction who had a coronary angiography performed within <3 months of the scintigraphic study were retrospectively evaluated. The same stress procedures were followed in all patients. (1) Only exercise when it was sufficient; and (2) exercise + simultaneous administration of dypiridamole if exercise was insufficient. Only reversible defects were considered positive and > or =50% of coronary stenosis was considered significant. RESULTS: Prevalence of reversible anterior and septal defects was low (33% and 12%, respectively) in patients with LBBB. Although lower values of global sensitivity (81%) and specificity (73%) were obtained in these patients, there were no significant differences with respect to the patients without LBBB (89% and 86%, respectively). Specificity values for the diagnosis of stenosis of left anterior descending (78%), left circumflex (96%) and right coronary artery (74%) in patients with LBBB were lower, but without significant statistical differences with respect patients without LBBB (90%, 96% and 82%, respectively). CONCLUSIONS: Myocardial SPECT with technetium compounds, using standard provocation manoeuvres, can be used in patients with LBBB with only a mild decrease in diagnostic accuracy as compared to patients without LBBB.     

Observer variation in the interpretation of lower limb venograms.

After agreeing on diagnostic criteria and after a pilot study, two experienced radiologists twice independently reviewed 40 lower limb venograms performed by a standard technique in patients suspected or known to have venous thrombosis. The observers reviewed 20 examinations at a time, their analysis requiring separate identification of 11 major veins. At each site observers stated whether thrombus was "absent," "doubtful," "presumed," or "definite," or declared "no opinion possible." They then rediscussed criteria of diagnosis and, using the same experimental design, examined another 40 venograms. To correct for agreement expected by chance, data were analyzed by using the kappa statistic. In general, levels of agreement were higher than those reported for many other clinical and radiologic investigations, probably because of refinement of criteria after the pilot study. Nonetheless, observers disagreed about the probable presence or absence of thrombus at some site in the limb in about 10% of examinations. Observer variation should be considered when venography is used as a reference standard to evaluate other methods of diagnosing thrombi.     

Medical disqualification of 275 commercial pilots: changing patterns over 20 years

INTRODUCTION: The medical requirements for commercial pilots are issued by the ICAO and the European aviation safety organization JAA. In Norway, the Aeromedical Section of the Civil Aviation Authority assesses whether pilots are medically fit to fly. This study presents the reasons for medical disqualification among the Norwegian commercial pilot population during a 20-yr period. METHODS: Files on all disqualified commercial pilots were reviewed and subdivided into age groups and diagnostic categories. Different disqualification rates were calculated. RESULTS: From the study population of 48,229 pilot-years, 275 pilots were permanently grounded, which gives a 20-yr average disqualification rate of 5.7 per 1,000 pilot-years. DISCUSSION AND CONCLUSIONS: For cardiovascular diseases the disqualification rate was lower after 1997 than before, which is explained by improved treatment and more lenient requirements. In the diagnostic categories, neurology, musculoskeletal, and psychiatric diseases, the disqualification rate increased after 1997. This fact is probably not attributed to more stringent health requirements, but possibly to the attitudes of the pilots, who have become more critical with respect to their subjective perception of their working environment and psychosocial factors.     

Predictive variables for hard cardiac events and coronary revascularization in patients with normal left ventricular myocardial perfusion and systolic function

Background

The objective of this study was to investigate the impact of clinical, electrocardiographic and stress testing variables in predicting hard cardiac events (HE) and coronary revascularization (CR) in patients with normal stress–rest gated SPECT.

Materials and methods

Included in the study were 2,004 patients (63.5?±?12.5 years, 41.6 % men) with normal myocardial perfusion and left ventricular ejection fraction (LVEF) >50 % on gated SPECT who were followed for HE (cardiovascular death or acute myocardial infarction) and CR.

Results

During a follow-up of 4.3?±?2.4 years, 33 patients (1.6 %; 0.4 %/year) had HE and 50 patients (2.5 %; 0.6 %/year) underwent CR. In a univariate analysis, age ≥65 years, insulin-dependent diabetes mellitus (IDDM), left bundle branch block (LBBB), and pharmacological stress were associated with HE. Independent predictors of HE were age ≥65 years (p?<?0.001; HR 6.9), IDDM (p?=?0.014; HR 3.4), and LBBB (p?=?0.002; HR 4.6). In the univariate analysis, male gender, LVEF, known coronary artery disease (CAD), LBBB, and a positive stress test were associated with CR. Independent predictors of CR were known CAD (p?=?0.016; HR 2.1), and a positive stress test (p?=?0.006; HR 2.3).

Conclusion

Age ≥65 years, IDDM, and LBBB are HE-independent predictors in patients with normal myocardial perfusion and normal LVEF on gated SPECT. The presence of known CAD or a positive stress test significantly increases the probability of CR during follow-up.     

Detection of mechanical ventricular asynchrony by high temporal resolution cine MRI

The purpose was to assess the feasibility of high temporal resolution cine MRI (HTRC-MRI) to detect and to quantify mechanical ventricular asynchrony in patients with left bundle branch block (LBBB). Inter- and intraventricular delays were quantified by HTRC-MRI in 32 patients with (n=17) and without (n=15) LBBB. In patients with LBBB, delays by HTRC-MRI were correlated with echocardiographic parameters using pulsed wave Doppler echocardiography (PW-Echo) and tissue Doppler imaging (TDI-Echo). The interventricular delay by HTRC-MRI was 110+/-50 ms in patients with and -1+/-18 ms in patients without LBBB (P<0.0001). The intraventricular delay was 336+/-86 ms in patients with compared to 40+/-49 ms in patients without LBBB (P<0.0001). A strong correlation (r=0.78, P=0.0002) and good agreement (mean difference: 39+/-36 ms) was found for the interventricular delay between HTRC-MRI and PW-Echo. A good correlation (r=0.66, P=0.0042), but a large discrepancy (mean difference: 257+/-64 ms) was found for the intraventricular delay between HTRC-MRI and TDI-Echo. Detection and quantification of mechanical ventricular asynchrony using HTRC-MRI is feasible. However, further comparison with other imaging modalities is required.     

Risk stratification and prognostic assessment by myocardial perfusion-gated SPECT in patients with left bundle-branch block and low-intermediate cardiac risk

Objective

In high-risk patients with left bundle-branch block (LBBB), functional but not perfusion parameters yield incremental prognostic information. The aim of our study was to evaluate the prognostic value of gated single photon emission computed tomography (SPECT) in low-intermediate risk LBBB patients.

Methods

One hundred seventy-six subjects underwent stress-rest dual-day protocol 99mTc sestamibi-gated SPECT and were dichotomized in two groups: without LBBB (Group 1, n = 86) and with LBBB (Group 2, n = 90). Patients were followed for 32 ± 18 months. Cox regression multivariate analysis was used to determine which variable was the best predictor of cardiac event. Event-free survival curves were computed by Kaplan–Meier method.

Results

Myocardial perfusion scintigraphy was abnormal in 32 and 60 patients for Groups 1 and 2, respectively (37 vs. 67 %, p < 0.001). In Groups 1 and 2, the mean summed stress score (SSS) was 3.7 ± 5.6 versus 6.7 ± 6.4, while the mean summed difference score (SDS) was 1.6 ± 2.5 versus 2.7 ± 3.3 (both p < 0.005); therefore 34 % of patients in Group 1 and 53 % of those in Group 2 presented myocardial ischemia. All functional parameters were significantly different between the two subsets (all p < 0.005). Follow-up was completed in 161 patients (92 %); 10 events occurred in Group 1 and 20 in Group 2 (14 vs. 25 %). The event-free survival was significantly higher in patients with normal than in those with abnormal scan (85 vs. 63 %, p < 0.005); moreover, the prognosis of patients with LBBB was significantly worse. At multivariate analysis, SDS was found to be the only independent predictor of cardiac events both in all patients and in LBBB population (HR 3.08, and HR 4.99, p < 0.05).

Conclusions

This is the first study to assess the prognostic value of gated SPECT in patients with LBBB and low-intermediate cardiac risk. Both perfusion and functional data obtained by gated SPECT are different between patients with and without LBBB. However, SDS is the only predictor of events. Thus, the amount of reversible ischemia at gated SPECT has a discriminative power in stratifying the cardiac risk of LBBB population.

     

A comparison of the routine medical examination of pilots in 12 air forces.

All air forces use routine medical examination to ensure the health of their pilots and flying safety. I compared pilot physicals in 12 air forces, and reviewed literature dealing mainly with routine medical examination of asymptomatic individuals. The discussion considers what should be done during the routine pilot examination to ensure flying safety, health and mission completion. General recommendations are given on ways to keep cost and effort within limits without failing to achieve the objective. Methods to achieve this include differentiating the intervals between examinations in different age groups and inclusion of procedures only beyond a certain age. Caution is advised when considering the inclusion of new procedures, and attention should be paid to whether such a test can be expected to produce unacceptable numbers of false positive results.     

Thallium-201 myocardial SPECT in left bundle branch block: Diagnosis of myocardial ischemia with a disease-specific reference database

Background  The aim of this study was to assess the value of a myocardial perfusion single photon emission computed tomography (SPECT) reference file for patients with left bundle branch block (LBBB). Methods and Results  Tl-201 stress-redistribution myocardial perfusion SPECT studies of patients with complete, permanent LBBB were reviewed retrospectively. To develop a reference database, 18 patients with a low likelihood of coronary artery disease (CAD) were selected. Left ventricular regional average and standard deviation (SD) values of the reference file images were calculated. The diagnostic performance was tested on perfusion images of 49 patients with LBBB, undergoing both scintigraphic and coronary angiographic evaluation, and was compared with a commercial quantitative analysis system using a general reference database. The LBBB reference file performed significantly better in detecting epicardial CAD than did the general reference database (receiver operating characteristic area under the curve 0.835 ± 0.06 vs 0.580 ± 0.08, p < .01). Disease localization also was improved significantly in the territory of the left anterior descending and of the right coronary arteries. Conclusions  The use of a reference file of patients with LBBB and a low likelihood of CAD aids the detection and the localization of myocardial ischemia on Tl-201 myocardial SPECT images of this patient group. The authors thank Professor Mátyás Keltai MD and István Szilvási MD for valuable discussions. The authors also thank József Turák (Mediso Ltd., Budapest, Hungary) for providing technical information on the Interview image processing system.     

LBBB in aircrew with low cardiac risk: diagnostic application of multislice CT

INTRODUCTION: Because of its excellent negative predictive value for diagnosing coronary stenoses, multislice computed tomography (MSCT) may be a way to assess the absence of significant coronary stenosis. We discussed its place in aeromedical decision-making for aircrew members with a low level of cardiovascular risk factors and acquired left bundle branch block (LBBB). METHODS AND RESULTS: During the period 2002-2004, 12 male aircrew members (mean age: 42.9 yr) with acquired LBBB were admitted to our cardiovascular and aeronautical department. The exploration of LBBB was classical, including an electrophysiological study, the usual coronary angiography, and MSCT. All the morphological explorations of the coronary tree were normal. DISCUSSION: In addition to complex electrophysiological mechanisms, coronary artery disease (CAD) is suspected, but remains infrequent in some EKG findings such as acquired LBBB, especially for patients with low cardiovascular risk factors as demonstrated with our aircrew members. However, in aerospace medicine the expert needs to prove the absence of CAD. The use of standard examinations (exercise stress test, stress myocardial scintigraphy, etc.) is controversial because of artifacts and a conventional coronary angiography is necessary. According to previous studies, including using a validated technique in our department (with 16-slice computed tomography), the excellent negative predictive value of MSCT (97 to 99%) may be a way to avoid invasive exploration during the investigation of a newly acquired LBBB in aviators with low cardiovascular risk.     

Early and delayed Tc-99m-tetrofosmin myocardial SPECT in patients with left bundle branch block

To determine the utility of the myocardial tracer Tc-99m-tetrofosmin in the examination of patients with left bundle branch block (LBBB) and to investigate Tc-99m-tetrofosmin uptake and retention in the myocardium, early and delayed Tc-99m-tetrofosmin SPECT was performed in 10 patients having LBBB without coronary stenosis.Methods: After 740 MBq of Tc-99m-tetrofosmin injection in the resting state, the early and delayed SPECT imaging was done at 30 min and 180 min, respectively.Results: Decreased Tc-99m-tetrofosmin uptake in the septal segments was observed in 4 patients (40%) at 30 min and in 9 (90%) at 180 min. Reverse redistribution was seen in 9 of 10 patients. In patients with LBBB, the septal-to-lateral uptake ratio was lower in the delayed images than in the early images (0.80 ± 0.09 vs. 0.89 ± 0.09, p < 0.001). In patients with LBBB, the washout rate of Tc-99m-tetrofosmin was higher in the septal segments than in the lateral segments (28.3 ±4.3% vs. 22.8 ± 3.3%, p < 0.001).Conclusion: The SPECT data indicate that in LBBB without coronary stenosis, the uptake of Tc-99m-tetrofosmin is decreased in the septal wall, and that reverse redistribution occurs frequently. Our results contribute to the elucidation of both the cellular biokinetics of Tc-99m-tetrofosmin in the myocardium and the hemodynamics of the septum in LBBB, and indicate the possible clinical utility of Tc-99m-tetrofosmin.     

Diagnostic value of history-taking and physical examination for assessing meniscal tears of the knee in general practice.

OBJECTIVE: To assess the diagnostic value of history-taking and physical examination of meniscal tears in general practice. DESIGN: An observational study determining diagnostic values (sensitivity, specificity, predictive value, and likelihood ratios). SETTING: General practice. PATIENTS: Consecutive patients aged 18 to 65 years with a traumatic knee injury who consulted their general practitioner within 5 weeks after trauma. ASSESSMENT: Participating patients filled out a questionnaire (history-taking) followed by a standardized physical examination. MAIN OUTCOME: Assessment of meniscal tears was determined by means of magnetic resonance imaging (MRI) and was performed blinded for the results of physical examination and history-taking. RESULTS: Of the 134 patients included in this study, 47 had a meniscal tear. From history-taking, the determinants "age over 40 years," "continuation of activity impossible," and "weight-bearing during trauma" indicated an association with a meniscal tear after multivariate logistic regression analysis, whereas from physical examination only "pain at passive flexion" indicated an association. These associated determinants from history-taking showed some diagnostic value; the positive likelihood ratio (LR+) reached up to 2.0 for age over 40 years, whereas the isolated test pain at passive flexion from physical examination has less diagnostic value, with an LR+ of 1.3. Combining determinants from history-taking and physical examination improved the diagnostic value with a maximum LR+ of 5.8; however, this combination only applied to a limited number of patients. CONCLUSION: History-taking has some diagnostic value, whereas physical examination did not add any diagnostic value for detecting meniscal tears in general practice.     

Gadolinium-based contrast agents in angiography and interventional radiology

Gadolinium is useful as an alternative contrast agent for diagnostic angiographic and interventional procedures in patients with renal insufficiency or a history of a severe reaction to iodinated contrast material. Gadolinium usually is used as a "problem solver" to answer specific diagnostic questions or guide interventional procedures that cannot adequately be defined with CO2 angiography. Because of dose limitations with Gd, careful planning is required prior to its use with angiography or interventional procedures.     

飞行员肺隔离症的诊断、治疗及医学鉴定原则——附二例临床病例

目的 探讨肺隔离症的影像学表现、治疗和飞行员的医学鉴定原则. 方法 回顾分析两例确诊为肺隔离症的飞行员的临床诊治过程及医学鉴定,并进行相关文献复习. 结果 肺隔离症临床症状不典型,1例叶外型肺隔离症无任何临床症状,在体检过程中发现;另1例叶内型肺隔离症反复咯血,多次按肺炎等诊治,存在误诊、漏诊.影像学检查对诊断有重要意义,其中胸部X线片多作为初筛,薄层CT、CT增强及血管重建对发现异常动脉有意义,但最可靠的方法为主动脉血管造影检查.对诊断明确者多主张积极治疗,本文中1例叶内型肺隔症者采用先进的经导管动脉栓塞治疗,最终恢复飞行;另1例叶外型肺隔离症者已恢复飞行至最高年限. 结论 肺隔离症临床少见,飞行员更是罕见,易误诊、漏诊,应重视年度体检中胸部X线检查.肺隔离症在无临床症状的非战斗机飞行员可个别评定,有临床症状者采用微创介入治疗对肺功能影响小,有望恢复飞行.同时提示航空医师加强对少见先天性疾病的诊断意识,治疗时综合考虑各种治疗手段对飞行能力的影响,一些先进的治疗方法能最大限度地挽救飞行员的职业生涯.     

Prognosis in patients with left bundle branch block and normal dipyridamole thallium-201 scintigraphy

Background  The presence of complete left bundle branch block (LBBB) is commonly associated with a poorer prognosis, especially in patients with coronary artery disease (CAD). In the general population with suspected CAD and normal intraventricular conduction, a normal dipyridamole-thallium scintigraphy is a strong marker of a favorable outcome. Objective  Our objective was to assess the prognosis in patients with LBBB and a normal dipyridamole thallium-201 scintigram. Population and methods  Patients with complete LBBB and normal myocardial perfusion on dipyridamole SPECT thallium-201 scintigraphy performed in our center for suspected CAD between 1988 and 1995 were monitored for clinical events. Results  Sixty-nine patients (36 women and 33 men) with a mean age of 59 years (range 56 to 61) were monitored for a mean period of 33 months (range 25 to 35). During this period, 4 patients had unstable angina, 2 of whom underwent myocardial revascularization. There were no deaths or myocardial infarction. All events occurred at least 2 years after the thallium-201 scintigraphy. Conclusion  The presence of a normal myocardial perfusion with dipyridamole thallium-201 scintigraphy in this group of patients with suspected CAD and LBBB was associated with a very good prognosis, a low rate of clinical events occurring only 2 years after the myocardial scintigraphy, and no hard events.     

Human factors of powered flight: the Wright brothers' contributions

Orville and Wilbur Wright of Dayton, OH, not only were the first to fly a powered aircraft, but also pioneered many human factors considerations. While others tried to develop aircraft with a high degree of aerodynamic stability, the Wrights intentionally designed unstable aircraft with "cerebralized" control modeled on bird flight. During 1901-03, the brothers worked with large gliders at Kill Devil Hills, near Kitty Hawk, NC, to develop the first practical human-interactive controls for aircraft pitch, roll, and yaw. On December 17, 1903, they made four controlled, powered flights over the dunes at Kitty Hawk with their Wright Flyer. During the next 2 yr, the Wrights made numerous flights in the Wright Flyers II and III at Huffman Prairie near Dayton. They later developed practical in-flight control of engine power, plus an angle-of-attack sensor and stick-pusher that reduced pilot workload. The brothers' flight demonstrations in the U.S. and Europe during 1908-09 awakened the world to the new age of controlled flight. Orville was the first aviator to use a seat belt. He also introduced a rudder boost/trim control that gave the pilot greater control authority. The Wrights' flight training school in Dayton included a flight simulator of their own design. The Wrights patented their practical airplane and flight control concepts, many of which are still in use today.     

Tc-99m sestamibi gated SPECT in patients with left bundle branch block

PURPOSE: The purpose of this study was to assess the diagnostic role of a Tc-99m sestamibi gated SPECT technique in patients with left bundle branch block (LBBB) without known coronary artery disease. MATERIALS AND METHODS: Twenty consecutive patients with constant complete LBBB were included. A same-day rest-stress protocol was used, and dipyridamole stress (14 patients) or treadmill exercise (6 patients) was applied. Electrocardiograph (ECG)-gated SPECT images were acquired 15 minutes after the administration of 0.31 mCi/kg Tc-99m sestamibi at peak stress. Regional myocardial perfusion was analyzed in relation to the cardiac cycle. RESULTS: Eleven of 14 patients who underwent a dipyridamole stress test had hypoactivity in the left anterior descending (LAD) artery territory in the ungated (summed) stress-rest images (abnormality ratio, 78%). On the ungated images, the abnormality was completely reversible in one patient (9%), partially reversible in five patients (46%), irreversible in two patients (18%), and reverse perfusion was identified in three patients (27%). Abnormality ratios of end-systolic and end-diastolic data were 93% and 29%, respectively. Conversely, the ungated rest-stress and end-systolic images of all the patients who performed treadmill exercise were abnormal despite the presence of normal or nearly normal end-diastolic myocardial perfusion. The angiographic findings correlated best with those of end-diastolic images. In 13 patients without coronary artery disease, normal or nearly normal regional perfusion was observed on end-diastole, but four patients with abnormal end-diastolic perfusion, which involved the LAD territory in all but one, had substantial coronary artery disease. The number of the involved segments was similar on the end-systolic and ungated data. Most of these artifactual defects were localized to the anteroseptal, septal, and inferoseptal segments. CONCLUSIONS: These preliminary data indicate that end-diastolic images can significantly reduce artifactual defects in patients with LBBB. The resolution of an LBBB pattern on end-diastolic data would significantly improve the diagnostic role of myocardial perfusion studies in these patients.     

Myocardial scintigraphy with thallium-201 and technetium-99m-hexakis-methoxyisobutylisonitrile in left bundle branch block: a study in patients with and without coronary artery disease

In left bundle branch block (LBBB) thallium-201 myocardial scintigraphy frequently reveals septal abnormalities in the absence of coronary artery disease (CAD) and gives rise to false-positive results in patients with suspected CAD. It has not yet been clarified which pathophysiological mechanism is responsible for these perfusion abnormalities. A total of 66 patients with constant LBBB were investigated with ²⁰¹T1 or technetium-99m-hexakis-methoxyisobutylisonitrile (MIBI), 62 underwent coronary angiography. Of 12 patients without left anterior descending artery (LAD) or right coronary artery (RCA) stenoses, 11 had a reversible septal activity deficit after ²⁰¹T1 stress injection, whereas 20 of 22 patients without relevant CAD showed a constant stress/rest septal deficit using MIBI. Regarding patients with significant LAD and/or RCA stenoses, both radiopharmaceuticals almost always showed a reversible septal deficit: with ²⁰¹T1 in 15 of 16 individuals and with MIBI in 14 of 15. In 12 patients ²⁰¹T1 was reinjected at rest. In those who had LAD or RCA stenoses (n = 5), early septal activity uptake after stress injection was poorer than that after rest injection; in the absence of CAD (n = 7), septal stress uptake corresponded with that of rest injection. It is concluded that septal perfusion abnormalities in LBBB and the absence of CAD are characterized by an exercise-independent reduction of septal blood flow per mass of viable myocardium and that stress/rest injection protocols of myocardial perfusion tracers are able to differentiate between LBBB with and without CAD.Dedicated to Prof. Dr. Dr. h.c. H. Hundeshagen on the occasion of his 65th birthday Correspondence to: W.H. Knapp     

Utilization of diagnostic medical imaging: comparison of radiologist referral versus same-specialty referral

PURPOSE: To retrospectively compare the frequency with which patients underwent diagnostic medical imaging procedures during episodes of outpatient medical care according to whether their physicians referred patients for imaging to themselves and/or physicians in their same specialty or to radiologists. MATERIALS AND METHODS: Institutional review board approval was not necessary for this HIPAA-compliant study. An insurance claims database from a large national employer-based health plan was obtained. Claims data from 1999-2003 were grouped into episodes of care for six conditions: cardiopulmonary disease, coronary and/or cardiac disease, extremity fracture, knee pain, intraabdominal malignancy, and stroke. For each condition, each referring physician's behavior was categorized as either "same-specialty referral" or "radiologist referral" on the basis of that physician's entire history of imaging referrals for the condition. The frequency with which patients underwent diagnostic medical imaging procedures during episodes of care was compared according to whether their physicians referred patients for imaging to themselves and/or same-specialty physicians or to radiologists. Rates were compared by using chi(2) tests, and logistic regression was used to compare utilization rates, with patient age and number of comorbidities as covariates. RESULTS: For the conditions evaluated, physicians who referred patients to themselves or to other same-specialty physicians for diagnostic imaging used imaging between 1.12 and 2.29 times as often, per episode of care, as physicians who referred patients to radiologists (P < .005 for all comparisons). Adjusting for patient age and comorbidity, the likelihood of imaging was 1.196-3.228 times greater for patients cared forby same-specialty-referring physicians. CONCLUSION: Same-specialty-referring physicians tend to utilize imaging more frequently than do physicians who refer their patients to radiologists. These results cannot be explained by differences in case mix (because analyses were performed within six specific conditions of interest), patient age, or comorbidity.     

Use of medical radiographs: extent of variation and associated active bone marrow doses

An analysis of radiologic practice in five areas of Maine was undertaken for three purposes: to identify those radiologic examinations associated with the highest variation in use so that guidelines can be instituted to correct for excess use; to identify the major contributors to absorbed dose to the active bone marrow; and to estimate annual and cumulative dose to the active bone marrow as a function of age. Our data indicate that variation in radiologic use is no larger, on average, than is variation in the use of surgical procedures and that the largest variations are found in mammograms and films of the skull and lumbar spine. For all patient age groups, four types of examinations contribute 75%-85% of the annual dose to the active bone marrow: examinations of the stomach and intestines using barium contrast material, intravenous urograms, studies of the biliary tract, and lumbar spine films. Over 80% of the total dose to the active bone marrow from diagnostic radiology in patients occurs after age 40 and nearly 60% after age 55; this suggests that the potential number of induced leukemias from diagnostic radiology may be lower than previously estimated.