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DOI: 10.1148/radiol.2203001429
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(Radiology. 2001;220:589-593.)
© RSNA, 2001

Musculoskeletal Imaging

MR Imaging of the Wrist: Effect on Clinical Diagnosis and Patient Care1

Jonathan L. Hobby, MB BS, FRCS, Adrian K. Dixon, MD, FRCP, FRCR, FMedSci, Philip W. P. Bearcroft, MA, MRCP, FRCR, Brian D. M. Tom, PhD, David J. Lomas, FRCP, FRCR, Neil Rushton, MD, FRCS and Murray H. Matthewson, FRCS

1 From the Orthopedic Research Unit (J.L.H., N.R.), Department of Radiology (A.K.D., P.W.P.B., D.J.L.), and Department of Trauma and Orthopedic Surgery (M.H.M.), Box 219, Addenbrooke’s Hospital, Hills Rd, Cambridge CB2 2QQ, England; and the Centre for Applied Medical Statistics, University of Cambridge Institute of Public Health, England (B.D.M.T.). Received August 19, 2000; revision requested September 26; final revision received March 16, 2001; accepted March 23. Supported by research fellowships from the NHSE (Eastern region) research and development directorate and the Royal College of Surgeons of England. The Addenbrooke’s Charities provided a grant to purchase imaging equipment. Address correspondence to A.K.D. (e-mail: akd15@radiol.cam.ac.uk).


   ABSTRACT
TOP
 ABSTRACT
INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 REFERENCES
 
PURPOSE: To evaluate the effect of magnetic resonance (MR) imaging of the wrist on clinicians’ diagnoses, diagnostic certainty, and patient care.

MATERIALS AND METHODS: A controlled observational study was performed. Referring clinicians completed questionnaires about diagnosis and intended management before and after wrist MR imaging. One hundred eighteen consecutive patients referred for MR imaging of the wrist were recruited from the MR imaging units at a regional teaching hospital and a large district general hospital. The main measures were changes in the clinicians’ leading and subsidiary diagnoses after MR imaging, their certainty in these diagnoses, and changes in intended patient care.

RESULTS: Questionnaires were incorrectly completed for five patients, questionnaires were not returned for three, appointments were canceled for 10, and two could not tolerate the MR examination. Complete follow-up data were available for 98 patients. The clinical diagnosis changed in 55 of 98 patients; in the remaining 43 patients, diagnostic certainty increased in 23. Clinicians reported that MR imaging had substantially improved their understanding of the disease in 67 of 98 patients. The care plan changed in 45 of 98 patients, with a shift away from surgical treatment. Twenty-eight patients were discharged without further investigation. MR imaging was similarly effective in the regional teaching center and the district general hospital.

CONCLUSION: MR imaging of the wrist influences clinicians’ diagnoses and management plans.

Index terms: Magnetic resonance (MR), utilization • Wrist, injuries, 43.40 • Wrist, MR, 43.121411, 43.121412, 43.121413, 43.121415


   INTRODUCTION
TOP
 ABSTRACT
 INTRODUCTION
MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 REFERENCES
 
Magnetic resonance (MR) imaging, with its capability of high-spatial-resolution multiplanar imaging of bone and soft tissues, has the potential to alter the diagnostic process in musculoskeletal disease. The availability of MR imaging is limited and, as with many new technologies, current demand exceeds supply. This expansion in demand has outpaced the published evidence of efficacy and effectiveness. The high capital costs of installing, maintaining, and operating machines with high magnetic field strengths have substantial implications for the funding of health care. Recent governmental policy in the United Kingdom (1) has the objective of "ensuring the best use of resources so that patients receive the greatest benefit" and states that care provided should be "effective—drawing on the best available clinical evidence, and efficient and economic—to maximize health gain for the population." Although published reports have indicated that MR imaging of the wrist is an accurate diagnostic tool (2–6), there have been few reports of its effect on clinical diagnosis and patient care. Indeed, the widespread use of MR imaging, in the absence of rigorous evaluations of its clinical effectiveness, has been questioned (7,8). This study was conducted to assess the effect of MR imaging of the wrist on clinicians’ diagnoses, diagnostic certainty, and patient care.


   MATERIALS AND METHODS
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
RESULTS
 DISCUSSION
 REFERENCES
 
All patients referred for MR imaging of the wrist at Addenbrooke’s Hospital, Cambridge, England, and Ipswich Hospital, England, during 18 months were included in this study. Addenbrooke’s Hospital is a regional teaching center that receives imaging referrals from its local catchment area and from four smaller nearby hospitals; Ipswich Hospital is a large district general hospital. Referrals were received from hospital specialists. Patients from both public and private hospitals were recruited for the study. The local research ethics committees in the two hospitals approved the study. The ethics committees considered that patient consent was not necessary.

A controlled observational study was performed to assess the clinical effectiveness of MR imaging of the wrist. The referring clinicians (orthopedic surgeons [N.R., M.H.M.] and rheumatologists) completed a structured request form, which was used to collect information about diagnosis, diagnostic certainty, and proposed management. The specialty and hospital of the referring clinician were recorded. Linear visual analog scales were used to record the clinicians’ estimates of the preimaging probability for the eight most common diagnostic groups—avascular necrosis, fracture, triangular fibrocartilage tear, ligament injury and/or instability, swelling and/or mass, degenerative or inflammatory arthritis, tendon and/or nerve injury, and carpal tunnel syndrome—and any other unspecified diagnoses. The scales used were 74 mm long, with a single dot at the midpoint. They were labeled with 0% at one end and 100% at the other, with no end anchor bars.

The intended management before imaging was considered in four groups: (a) discharge to primary care; (b) outpatient review, further investigation, referral to another specialist, or nonsurgical treatment; (c) arthroscopy (diagnostic or therapeutic); and (d) open surgery.

A follow-up form was sent with the written radiologic report for completion during the postimaging outpatient review. The follow-up questionnaire was used to collect the same information about diagnosis, diagnostic certainty, and management as on the initial MR imaging request form. In addition, the clinician’s assessment of the usefulness of each MR imaging examination was evaluated by using the following statements: (a) "MR imaging was confusing and led to investigations that I would not otherwise have done." (b) "MR imaging was confusing, but has not led to additional investigations." (c) "MR imaging had little or no effect on my understanding of this patient’s disease." (d) "MR imaging substantially improved my understanding of this patient’s disease." (e) "My understanding of this patient’s disease depended upon diagnostic information provided only by MR imaging (unavailable from any other nonsurgical procedure)."

At the end of the study period, the hospital notes were reviewed (by J.L.H.) to confirm the accuracy of the following information collected on the request and follow-up forms: pre- and postimaging differential diagnosis, pre- and postimaging management plan, and ultimate treatment.

Imaging Protocols
MR imaging was performed with a system (LX Horizon Echospeed; GE Medical Systems, Milwaukee, Wis) operating at 1.5 T (Addenbrooke’s Hospital) or with a system (Gyroscan; Philips, Eindhoven, the Netherlands) operating at 0.5 T (Ipswich Hospital). The examination protocols inevitably evolved during the study period, particularly when new coils and software were obtained. The standard imaging protocol at both centers comprised a coronal spin-echo T1-weighted sequence, a coronal three-dimensional gradient-echo T2*-weighted high-spatial-resolution sequence, and either a coronal fast spin-echo T2-weighted sequence with fat suppression (Addenbrooke’s Hospital) or a coronal short inversion time inversion-recovery sequence (Ipswich Hospital). Most patients underwent additional imaging in the transverse plane with dual-echo sequences. Appropriate receive-only surface coils were used. Experienced consultant radiologists (A.K.D., P.W.P.B., D.J.L.) reviewed the images and issued a report.

Data Handling and Analysis
Data analysis was performed by using STATA 5.0 software (Stata, College Station, Tex). The pre- and postimaging visual analog scale measurements were graded as shown in Table 1 and treated as ordinal variables. The grading was similar to that of previous studies (9,10) but was refined following a study of the reliability of visual analog scale measurements of diagnostic certainty (11). A shift from unlikely, uncertain, or probable to definite (confirmed) or very unlikely (excluded) was interpreted as an increase in diagnostic certainty. A change in certainty from definite to very unlikely (or vice versa) was also interpreted as an increase in diagnostic certainty. The McNemar test was used to test the hypothesis that diagnostic certainty increased after imaging. The Wilcoxon signed rank test was used to test the hypothesis that fewer diagnoses were considered after imaging than before. The McNemar test was used to test the hypothesis that the number of patients for whom surgery was planned changed after imaging. The {chi}2 test was used to test the hypothesis that a difference in the effectiveness of MR imaging existed between the two hospitals.


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  		TABLE 1. Grading of Visual Analog Scale Measurements

 

   RESULTS
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
DISCUSSION
 REFERENCES
 
One hundred eighteen patients (44 men, 54 women; mean age 35.4 years; age range, 12–75 years) were referred for imaging. Correctly completed request forms were returned for 113 (96%); of these, 103 were examined (four patients did not keep their appointments; six examinations were canceled by the patient or referring clinician). Seventy-four patients were examined at Addenbrooke’s Hospital; 29, at Ipswich. Two examinations were abandoned because of patient movement. In three patients, the follow-up form was not returned despite two written requests. Complete pre- and postimaging data were thus available for 98 patients.

Seventy-one of 98 referrals were from orthopedic surgeons, with the remaining 27 from rheumatologists. Before imaging, more than one diagnosis was being considered in 73 (74%) of 98 patients. There was a significant reduction in the number of diagnoses being considered after MR imaging (Table 2). In the patient with no preimaging diagnosis (Table 2), the referring clinician strongly suspected that no organic basis for the symptoms existed; MR imaging was requested to exclude occult disease and to reassure both the clinician and the patient.


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  		TABLE 2. Number of Diagnoses Considered before and after MR Imaging

 
Table 3 shows the changes in diagnostic certainty after MR imaging. The diagnosis changed after imaging in 55 (56%) of 98 patients. Twenty-nine new diagnoses were considered in 22 patients after imaging; 10 of these diagnoses were considered probable or definite. After imaging, 121 diagnoses being considered in 61 patients were excluded; 31 of these diagnoses had been considered probable or definite before imaging. There was greater diagnostic certainty (a shift away from the center of the scale) in 23 (53%) of the 43 patients in whom the initial diagnosis was retained after imaging. The number of diagnoses considered to be very unlikely or definite increased from 71 (27%) of 267 before MR imaging to 185 (69%) of 267 after MR imaging (McNemar test, {chi} = 11.0; P = .001). Both units showed significant increases in diagnostic certainty. The number of diagnoses considered very unlikely or definite increased from 50 (28%) to 135 (75%) of 181 at Addenbrooke’s Hospital (McNemar test, {chi} = 5.8; P = .016) and from 21 (24%) to 50 (58%) of 86 at Ipswich Hospital (McNemar test, {chi} = 7.4; P = .007).


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  		TABLE 3. Changes in Diagnostic Certainty after Imaging, for All Diagnoses under Consideration

 
Table 4 shows the clinician’s assessment of the usefulness of MR imaging. In 67 (68%) of 98 cases, the clinicians reported that imaging had substantially improved their understanding of the patient’s disease or that their understanding depended on information provided by MR imaging.


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  		TABLE 4. Assessment of the Value of MR Imaging

 
Table 5 shows the management plans before and after imaging. Management plans changed for 45 (46%) of 98 patients. Twenty-eight patients were discharged after imaging and thereby avoided further examination, which the clinician thought might be unnecesssary. these discharges prevented further investigation (arthroscopy in five and surgical exploration in three). Nineteen (43%) of 44 patients in whom surgery was planned before imaging were treated nonsurgically; four (7%) of 54 patients in whom nonsurgical treatment was planned were treated surgically. The shift away from surgery was statistically significant (McNemar test, {chi} = 28.4; P < .001).


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  		TABLE 5. Changes in Planned Management after Imaging

 
Changes in management plans were observed in both units: The intended management changed after imaging in 30 (42%) of 71 patients at Addenbrooke’s Hospital and in 15 (56%) of 27 patients at Ipswich Hospital. The specialties of the referring clinicians at the two centers were different: All but one of the referrals (26 [96%] of 27) at Ipswich Hospital were from orthopedic surgeons; at Addenbrooke’s Hospital, 45 (63%) of 71 referrals were from orthopedic surgeons and 26 (37%) were from rheumatologists. The preimaging management plans among rheumatologists did not include surgery, and direct comparisons of changes in management plans between the two centers are thus inappropriate. However, the changes in management for the orthopedic patients at the two centers were similar: Care changed in 21 (47%) of 45 patients at Addenbrooke’s Hospital and in 15 (58%) of 26 patients at Ipswich Hospital ({chi}2 = 0.65; P = .42).

A change in care was associated with a change in diagnosis in 29 (64%) of 45 patients and an increase in diagnostic certainty in 11 (24%). In only five (11%) of 45 patients in whom care changed after MR imaging did the diagnosis or diagnostic certainty remain the same. The diagnosis changed in 12 (63%) of 19 patients who avoided surgery. Diagnostic certainty increased in the remaining seven who avoided surgery, although they retained their preimaging diagnoses. In all four patients whose care changed from nonoperative treatment to surgery after MR imaging, the diagnosis changed. In the 53 patients whose care did not change after MR imaging, the diagnosis changed (n = 26 [49%]); the diagnostic certainty increased (n = 12 [23%]); or the diagnosis and diagnostic uncertainty were unchanged (n = 15 [28%]).

The clinical notes were reviewed in 74 (76%) of 98 patients; the notes for some private patients and patients referred to Addenbrooke’s Hospital from other hospitals were not always available. The notes made at the pre- and postimaging consultations were consistent with the data obtained for diagnoses and diagnostic certainty from the request and follow-up forms in all cases. However, the definitive care differed from the intended care after imaging in five patients: Three patients with an intended care plan of clinical review were discharged at the first postimaging appointment and did not return; two patients whose initial care plan involved review eventually underwent surgery. The data were adjusted accordingly before final analysis.


   DISCUSSION
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
REFERENCES
 
The effects of diagnostic imaging depend on a chain of events between the application of the technology and the outcome of treatment. Diagnostic imaging is requested by clinicians to assist in the diagnosis of disease or to aid in planning the treatment of a known disease process. A radiologist makes a report of the images obtained. The clinician combines the radiologic, laboratory, and clinical findings to make a working diagnosis on which the clinical management is based. Evaluating new imaging techniques is, therefore, a complex task (12–15).

We assessed diagnostic and therapeutic effects by using a controlled observational study design. The patients acted as their own control subjects, because their information was collected before and after imaging (16–19). An observational study was chosen instead of a randomized study for several reasons: It allows current clinical practice to be assessed with minimal interference to the normal care of the patient (15); it avoids the ethical difficulties of denying MR imaging to patients when it has become accepted as part of clinical practice (17,20); and the principal alternative is an invasive procedure (diagnostic arthroscopy), which may make clinicians reluctant to recruit patients into a randomized study (21–23).

The study was designed to minimize the recognized weaknesses of before-and-after studies (13,19). The data were prospectively collected to prevent potential observer bias, which is inherent in retrospective studies. The clinician completed the follow-up form without access to the request form; this design prevented the clinician from referring to the preimaging data before marking the postimaging form and deliberately biasing the data. The accuracy of the information provided was verified with an independent notes review. To increase the external validity of the study and minimize selection bias, we recruited a consecutive series of patients, from a wide range of referring clinicians, who were examined in two units (a teaching center and a district general hospital).

It is not surprising that most patients (74%) had more than one preimaging diagnosis, and MR imaging was available only if diagnostic uncertainty existed. (The wrist is a complex joint, and several lesions may coexist [eg, a ligament injury with a triangular fibrocartilage tear].) There was a significant reduction in the number of diagnoses being considered after MR imaging (Table 2). After imaging, more than one diagnosis was being considered in the minority (40%) of patients. There was an overall increase in diagnostic certainty following MR imaging (Table 3). The number of diagnoses considered definite or very unlikely increased from 27% before imaging to 69% after imaging.

The working diagnosis changed in more than half of the patients examined, and diagnostic certainty substantially increased in many of those patients in whom the initial diagnosis was retained. Refinements in diagnosis are clearly of value if they change management. They may also be useful if they provide reassurance or a firm and helpful prognosis to inform the clinician and the patient. Situations exist in which a change in diagnosis or diagnostic certainty does not alter management. The "quest for diagnostic certainty" has been proposed as a cause for excessive and redundant testing (24). In this study, many more diagnoses were excluded (n = 121) than confirmed (n = 64). Clinicians commonly place great value on investigations that help to rule out unlikely but serious conditions, and patient care may be altered by findings that corroborate a clinician’s suspicion that no disease process is present (25). MR imaging provides a noninvasive and cheaper alternative to diagnostic arthroscopy.

The care plan changed after MR imaging in 45 (46%) of the 98 patients. Notably, 19 (43%) of 44 patients whose care originally included surgery were treated nonsurgically after MR imaging (Table 5). A change in care was associated with a change in diagnosis or diagnostic certainty in 40 (89%) of 45 patients, and diagnosis or diagnostic certainty changed in all patients who changed from surgical to nonsurgical care (or vice versa). This study was conducted to assess the effectiveness of MR imaging of the wrist in a selected group of patients in whom diagnostic uncertainty existed after they were examined by an orthopedic surgeon or rheumatologist. Similar increases in diagnostic certainty and changes in management plans were observed in both units; these findings indicated the effectiveness of wrist MR imaging in both a district general hospital and a regional teaching center.

We recognize that the MR imaging findings are not the only possible explanation for changes in diagnosis and management that occurred between referral and follow-up. In the interval between questionnaires, there may have been arbitrary changes in reported diagnosis and management plans. However, this possibility would not explain the observed increase in diagnostic certainty or the association of the exclusion of disease with a shift toward nonoperative management. Some patients’ symptoms may have changed, or other sources of information may have become available. The clinicians’ subjective assessment that MR imaging substantially improved their understanding of the patients’ disease in two-thirds of cases supports the assumption that the imaging findings were responsible for the changes in diagnosis, diagnostic certainty, and management that we observed. However, such subjective opinions have been criticized as a potential source of confusion in the assessment of advances in imaging (21).

The study was designed to minimize the potential for observer bias, with prospective data collection and independent corroboration of the reported diagnosis and management plan. Guyatt et al (13) have stressed the tendency of observational study designs to cause overestimation of the therapeutic benefits of interventions, when compared with randomized controlled trials. In an attempt to counter this tendency, diagnostic certainty was considered to have increased only if the diagnosis was considered to be definite (more than 90% probability) or very unlikely (less than 10% probability) after MR imaging. For the assessment of whether MR imaging changed patient care, the data were analyzed as two groups: surgical or nonsurgical care.

In this study, we did not attempt to link the diagnostic and therapeutic effects of MR imaging of the wrist with the eventual outcome of the patients’ treatment. There are considerable difficulties in demonstrating changes in patient health or treatment outcomes with an observational study design in which all patients are examined (22), because without a control group we cannot know how the patients would have fared without MR imaging. Changes in patients’ health depend on the natural history of the disease, and the effectiveness and complications of treatment (15). The effect of imaging technologies on outcome is probably better addressed with comparative studies in which some patients undergo the examination and others do not (23).

For diagnostic imaging, the referring clinician is the consumer, and the clinicians in this study indicated that imaging increased diagnostic certainty and contributed to their understanding of the patients’ disease. The findings suggest that MR imaging of the wrist helps to refine the clinical diagnosis and alters the care of patients. Its findings may also prevent unnecessary diagnostic arthroscopy and exploratory surgery.


   ACKNOWLEDGMENTS
 
We thank all those who gave up their time to participate in this study, particularly the clinicians who completed the forms and allowed us to include their patients: the rheumatologists, orthopedic surgeons, and radiologists at Addenbrooke’s and Ipswich NHS trusts. We also thank the staff of the MR imaging units at both hospitals and Christine Wilson and Hazel Brown for administrative and secretarial assistance.


   FOOTNOTES
 
The MRI Unit at Addenbrooke’s NHS Trust receives financial support from the Fund for Addenbrooke’s and GE Medical Systems, London, England.

Author contributions: Guarantor of integrity of entire study, J.L.H.; study concepts, A.K.D., J.L.H., M.H.M., D.J.L., P.W.P.B.; study design, J.L.H., A.K.D., P.W.P.B., D.J.L., N.R., M.H.M.; literature research, J.L.H., A.K.D., P.W.P.B.; clinical studies, J.L.H., A.K.D., P.W.P.B., D.J.L., N.R., M.H.M.; data acquisition, J.L.H., M.H.M., P.W.P.B., D.J.L.; data analysis/interpretation, J.L.H., A.K.D., P.W.P.B., B.D.M.T.; statistical analysis, J.L.H., B.D.M.T.; manuscript preparation, J.L.H., A.K.D., B.D.M.T.; manuscript definition of intellectual content, A.K.D., J.L.H., P.W.P.B., M.H.M.; manuscript editing and revision/review, J.L.H., A.K.D., B.D.M.T., P.W.P.B., N.R.; manuscript final version approval, all authors.


   REFERENCES
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
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