Acutely injured knee: effect of MR imaging on diagnostic and therapeutic decisions

Simultaneous multi-slice accelerated turbo spin echo of the knee in pediatric patients

PURPOSE

To compare knee MRI performed with the integrated parallel acquisition technique (PAT) and simultaneous multislice (SMS) turbo spin echo (TSE) T2-weighted (T2w) sequences with conventional TSE sequences in pediatric patients.

MATERIALS AND METHODS

This was a retrospective IRB-approved study. Seventy-four subjects (26 male, 48 female, mean age 15.3 years, range 8-20) underwent 3-T MRI of the knee with a T2w TSE pulse sequence prototype with four-fold PAT and SMS acceleration as well as the standard PAT-only accelerated sequences. Images were anonymized and two study folders were created: one examination with only T2w PAT2 images (conventional examination) and one examination with only T2w SMS2/PAT2 sequences (SMS examination). Two readers rated examinations for 15 specific imaging findings and 5 quality metrics. Interreader agreement was measured. Signal to noise (SNR) and contrast to noise (CNR) were measured for SMS and conventional T2w sequences.

RESULTS

Consensus review demonstrated diagnostic quality performance of SMS examinations with respect to all 15 structures. Average area under the curve (AROC) was 0.95 and 0.97 for readers 1 and 2, respectively. The conventional sequence was favored over SMS for four out of five quality metrics (p < 0.001). SNR and CNR were higher for the conventional sequences compared to SMS.

CONCLUSION

SMS accelerated T2w TSE sequences offer a faster alternative for knee imaging in pediatric patients without compromise in diagnostic performance despite diminished SNR. The four-fold acceleration of SMS is beneficial to pediatric patients who often have difficulty staying still for long MRI examinations.

Association of the type of trauma, occurrence of bone bruise, fracture and joint effusion with the injury to the menisci and ligaments in MRI of knee trauma

BACKGROUND

magnetic resonance imaging (MRI) as a noninvasive diagnostic tool may help clinicians in the evaluation of injuries to menisci and ligaments.

PURPOSE

this study assessed the associations between type of trauma to knee joint, bone bruise, fracture and pathological joint effusion with injuries to menisci and ligaments of knee joint.

METHODS

we reviewed knee joint MRI of 175 patients aged less than 45 years old who were referred to MRI center of our University.

RESULTS

statistical analysis showed that tearing of medial meniscus (MM) is significantly more common in sport related trauma (p= 0.045) but tearing of medial collateral ligament (MCL) is significantly more common in non-sport related trauma (p= 0.005). Existence of bone bruise in knee MRI is negatively associated with tearing of medial meniscus (MM) (p=0.004) and positively associated with tearing of anterior cruciate ligament (ACL) (p=0.00047) and medial collateral ligament (MCL) (p = 0.0001). Existence of fracture is associated with decreased risk of the tearing of ACL and MM (p=0.04, p=0.001 respectively). Pathologic joint effusion is significantly more common in ACL and MCL tearing (p=0.0001, p=0.004 respectively).

CONCLUSIONS

as diagnostic clues, bone bruise, fracture and joint effusion may help radiologists for better assessment of injury to menisci and ligaments in MRI of patients with knee trauma.

Determining bone bruises of the knee with magnetic resonance imaging

Introduction

Injuries that develop secondary to minor traumas and cannot be detected via direct examination methods, but are detected via advanced imaging methods, such as magnetic resonance (MR) imaging, are called occult bone injuries or bone bruises. In such injuries, diagnostic arthroscopy usually does not reveal any pathology. MR imaging methods are quite beneficial for the diagnosis of such clinical conditions, which cause acute pain and restriction of motion. The present study aimed to assess occult bone injuries via MR imaging in patients who presented with minor knee trauma.

Patients and Methods

Twelve patients who presented with minor knee trauma were included in the study. Etiological factors in these patients included walking a long distance, falls, and minor trauma. All patients underwent physical examinations, direct radiological imaging, MR imaging, and diagnostic arthroscopy.

Results

Direct radiographs of the patients showed no pathological fracture. Bone marrow changes detected on the MR images were classified according to Lynch’s classification as Type I lesions in nine patients and Type II lesions in three patients.

Conclusion

We suggest that MR imaging methods should be the gold standard for the diagnosis of minor traumatic bruise injuries of the knee.

Efficacy of repeat magnetic resonance imaging of the knee

A patient often initially presents to an orthopedic surgeon with the magnetic resonance image (MRI) ordered by his or her primary care physician in hand. Often, a significant period of time elapses after injury before the patient is assessed by the orthopedic surgeon; therefore, the initial MRI may be considered outdated because of a new injury or a change in symptoms or because the orthopedist may prefer a new study, a stronger magnet, or a special imaging protocol. However, the decision to repeat a knee MRI is presently an arbitrary one because no clinical guidelines exist to justify this practice.All repeat knee MRIs performed at our academic institution in the past 9 years were retrospectively examined. Inclusion criterion was repeat MRI of the same knee with no surgical intervention. The formal radiology reports were grouped into 3 categories: change, no change, and unclear. Knee pathology was further grouped into 6 categories indicating what specific structures were pathological or injured. Logistic regression analysis was used to test the association of time vs category or condition change between MRIs. Of 3501 knee MRI studies, 88 patients had a total of 101 repeat MRIs. The average number of days between repeats for those with category or condition change was 612 vs 504 for those with no change. Age, sex, and time between MRIs were not significantly associated with a category or condition change. Repeat knee MRI prior to surgical intervention is becoming more prevalent and may have clinical merit. A further prospective study is warranted.

Diagnostic and therapeutic impact of MR enterography in Crohn's disease

AIM

To assess the impact of magnetic resonance enterography (MRE) on clinician diagnostic confidence and therapeutic strategy in patients under investigation for small bowel Crohn's disease.

MATERIAL AND METHODS

Gastroenterologists completed a proforma before and following MRE in 51 patients (mean age 35 years, 26 female) under investigation for small bowel Crohn's disease, indicating percentage confidence for presence/absence of small bowel involvement. In suspected disease, diagnostic confidence (using a scoring system from 1=no to 6=yes) was scored for subcategories: extent >30 cm (DE), terminal ileum (lTI), jejunal (JD), colonic disease (CoD), strictures (ST), activity (AD), extraluminal complications (EL), and surgical need (NS). Therapeutic strategy was recorded. Patients were divided into three groups: 1=suspected disease, MRE normal (n=15); 2=suspected disease, MRE abnormal (n=30); 3=no suspected disease, MRE normal (n=6). Binomial exact and paired t-tests were use to compare confidence pre and post-MRE.

RESULTS

Mean percentage confidence for the presence/absence of small bowel disease increased from 62 to 84% (p=0.003), 87 to 98% (p=0.0001), and 83 to 98% (p=0.005) after MRE for groups 1, 2, and 3, respectively. In suspected disease, confidence changed significantly for all of the subcategories (p<0.001) except EL in group 1. The percentage of patients with a confidence change ranged from 40% (CoD) to 87% (lTI; group 1) and from 7% (EL) to 93% (DE; group 2). Therapeutic strategy changed in 31/51 (61%, 95% CI 47-74%), 14 with a reduction in planned therapy and 17 with an increase.

CONCLUSION

MRE had a positive diagnostic impact in patients under investigation for small bowel Crohn's disease and this influenced therapeutic strategy in 61% of the patients.

Real time spatial compound ultrasound in the evaluation of meniscal injuries: a comparison study with conventional ultrasound and MRI

The aim of this study was to compare real time spatial compound ultrasound (RTCS) and conventional ultrasound with MRI in the evaluation of meniscal injuries. Thirty five patients with clinical suspicion of meniscal injury underwent ultrasound of knee alternating between conventional and compound sonography followed by MRI of the knee on a 1.5 T MR system. The images were compared for their quality and ability to detect meniscal tear. Compound ultrasound significantly improved definition of soft tissue planes, reduced speckle and other noise, improved contrast resolution (p value<0.05) with improved confidence in detection of tears in doubtful cases. Interobserver variability was seen only for conventional ultrasound and the sensitivity, specificity, accuracy were 83.3%, 87.5% and 85.7% for the first observer and 80%, 87.5% and 84.3% for second observer. For compound ultrasound it was same for both the observers with sensitivity, specificity and accuracy being 90% each. Although compound ultrasound improves image quality in the evaluation of meniscal injuries the benefit with respect to detection of tears is only marginal. It is a valuable tool for screening the patients before MRI and we recommend that instead of conventional ultrasound, compound ultrasound should be routinely used for sonographic evaluation of meniscal injuries.

MRI for Traumatic Knee Injury: A Review

Magnetic resonance imaging (MRI) is a well-established technique for detecting internal derangements of the knee joint with high diagnostic accuracy. It is an effective tool to select patients for targeted therapeutic arthroscopy. In this article, indications for knee MRI and most commonly used MRI techniques are outlined, followed by an overview of the most frequently encountered traumatic knee derangements in daily practice and their appearance and grading system on MRI. Lesions discussed include fractures, osteochondral lesions, bone bruise, cruciate and collateral ligament lesions, and meniscal tears. Finally, common pitfalls and recent developments in knee MRI are addressed.

The diagnostic value of MRI in foot and ankle surgery

BACKGROUND

MRI is being used with increasing frequency and seems to have become more popular as a screening tool rather than as an adjunct to narrow specific diagnoses or plan operative interventions. Our hypothesis was that the rising accessibility of this test may be resulting in its overuse.

METHODS

We retrospectively reviewed 221 consecutive patients referred over a 3-month period for treatment of a lower extremity problem to determine: (1) the number of patients who presented with an MRI already obtained from an outside source, (2) the number of patients who obtained an MRI from the foot and ankle specialist after referral, and (3) the number of times the foot and ankle specialist used these studies or found them helpful in the care of the patient. Fractures (20) were excluded.

RESULTS

Of the 201 patients without fractures included in the study, 19.9% (40 of 201) had MRI scans during the course of their treatment; 15.4% (31 of 201) presented to their initial visit with an MRI scan from an outside source, and 4.5% (9 of 201) received MRI scans as ordered by the foot and ankle specialist. Eighty-seven percent (27 of 31) of the pre-referral MRI scans were thought to be unnecessary, and 48.4% (15 of 31) had radiographic interpretations that were considered either immaterial to the patient's pertinent clinical diagnosis or inconsistent with the specialist's interpretations. All nine MRI scans ordered by the specialist were useful in the care of the patient. Therefore, of the 221 consecutive patients, the foot and ankle specialist would have ordered MRI scans in only 5.9% (13 of 221).

CONCLUSIONS

This study suggests that many of the pre-referral foot or ankle MRI scans obtained before evaluation by a foot and ankle specialist are not necessary. Further studies need to be performed to determine the role of MRI in the screening of foot and ankle disorders.

Characteristics of Displaceable and Nondisplaceable Meniscal Tears at Kinematic MR Imaging of the Knee

PURPOSE

To prospectively determine if kinematic magnetic resonance (MR) imaging of the knee may demonstrate displacement of menisci with tears and, if so, to characterize displaceable and nondisplaceable meniscal tears.

MATERIALS AND METHODS

The study was approved by the hospital's review board, and informed consent was obtained. Forty-two patients (30 men, 12 women; mean age, 36.9 years) with 43 arthroscopically documented meniscal tears visible at 1.5-T MR imaging underwent kinematic MR imaging with an open-configuration 0.5-T MR imager with their knees in supine neutral, supine with 90 degrees flexion and external or internal rotation, and upright weight-bearing positions. Analysis of meniscal movement was performed in different knee positions in the coronal MR imaging plane. Meniscal displacement--that is, meniscal movement of 3 mm or more (in the medial direction for the medial meniscus, in the lateral direction for the lateral meniscus)--was compared with the patient's pain level as assessed with a visual analog scale by using analysis of variance.

RESULTS

Between the different knee positions, meniscal displacement of 3 mm or more (displaceable meniscal tears) was noted in 18 (42%) of 43 menisci with tears. Simultaneous occurrence of grade II or III ipsilateral collateral ligament lesions was present in all 18 displaceable meniscal tears, whereas a normal-appearing collateral ligament or collateral ligament lesion (grade I) was present in 22 of 25 nondisplaceable tears (P < .05). Displaced menisci most commonly had complex, radial, or longitudinal tear configurations (16 of 18, 89%). Patients with displaceable meniscal tears had significantly more pain than did patients with nondisplaceable meniscal tears (P < .001), independent of the concomitant knee abnormalities.

CONCLUSION

Displaceable meniscal tears usually have longitudinal, radial, or complex configurations; such tears are associated with substantial ipsilateral collateral ligament lesions and pain.

Fallstricke in der Magnetresonanztomographie des Kniegelenks

Magnetic resonance (MR) imaging of the knee is a robust method for the evaluation of internal derangements. A knowledge of the well known technical and anatomical pitfalls avoids, in most cases, diagnostic errors. However, the differentiation between meniscocapsular separation and normal anatomy remains challenging. The high prevalence of abnormal MR findings, especially meniscal tears with up to 63% on the asymptomatic contralateral side, has to be considered in patient management.

Overutilization of shoulder magnetic resonance imaging as a diagnostic screening tool in patients with chronic shoulder pain

This was a retrospective study of 101 consecutive patients (104 shoulders) with chronic, atraumatic shoulder pain who were evaluated by a fellowship-trained shoulder specialist. The patients were assessed with a complete history, physical examination, plain radiographs, Simple Shoulder Test, and visual analog scores of pain, shoulder function, and quality of life. Forty-one percent of the shoulders presented with shoulder magnetic resonance imaging (MRI). Data analysis was performed to determine the effect of pre-evaluation MRI on patient treatment and outcome. There were no statistically significant differences in age, sex, affected shoulder, insurance status, mechanism of injury, comorbid conditions, range of motion, treatment, initial outcome parameter assessments, or improvement of outcomes between the patients who had pre-evaluation MRI and those who did not. The majority of the pre-evaluation MRI scans had no impact on the outcome. Routine pre-evaluation with MRI does not appear to have a significant effect on the treatment or outcome and should not be used as a screening tool for atraumatic shoulder pain before a comprehensive clinical evaluation of the shoulder.

Altered signal intensity in the posterior horn of the medial meniscus: an MR finding of questionable significance

INTRODUCTION

MR imaging has emerged as an important modality in the non-invasive evaluation of osseous and soft-tissue structures in the post-traumatic knee. However, it is sometimes impossible to determine with confidence if a focus of high signal intensity in the meniscus is confined to the substance of the meniscus or if it extends to involve the joint surface. This is a critical differentiation because the latter represents meniscal tears that can be found and treated arthroscopically, whereas the former represents degeneration, intrasubstance tears or perhaps normal variants that are not amenable to arthroscopic intervention. The aim of this study was to investigate the occurrence of such borderline findings in relation to the posterior horn of the medial meniscus and to correlate the arthroscopic results.

MATERIALS AND METHODS

Sixty-four patients with suspected post-traumatic internal derangements of the knee who underwent MR imaging prior to arthroscopy were evaluated retrospectively. There were 48 men and 16 women. Their mean age was 28.2 years.

RESULTS

Tears of the posterior horn of the medial meniscus were diagnosed unequivocally (grade 3 signal) in 18 patients and equivocally (grade 2/3 signal) in 10 patients. Arthroscopic correlation revealed 16 tears (89%) in the unequivocal group and only 1 tear (10%) in the equivocal group.

CONCLUSION

A meniscal tear is unlikely when MR shows a focus of high signal intensity in the posterior horn of the medial meniscus that does not unequivocally extend to involve the inferior or superior joint surface. An appropriate trial of conservative treatment is recommended in such questionable cases. MR is a useful diagnostic tool-however, it should be used selectively, and in conjunction with history and clinical examination in evaluating internal derangements of the knee.

Clinical diagnostic accuracy and magnetic resonance imaging of patients referred by physical therapists, orthopaedic surgeons, and nonorthopaedic providers

STUDY DESIGN

Nonexperimental, retrospective design.

OBJECTIVES

This study was designed to compare clinical diagnostic accuracy (CDA) between physical therapists (PTs), orthopaedic surgeons (OSs), and nonorthopaedic providers (NOPs) at Keller Army Community Hospital on patients with musculoskeletal injuries (MSI) referred for magnetic resonance imaging (MRI).

BACKGROUND

US Army PTs are frequently the first credentialed providers privileged to examine and diagnose patients with musculoskeletal injuries. Physical therapists assigned at Keller Army Community Hospital have also been credentialed with privileges to order MRI studies for several years.

METHODS AND MEASURES

To reduce provider bias, a retrospective analysis was performed on 560 patients referred for MRI over an 18-month period. An electronic review of each patient's radiological profile was performed to assess agreement between clinical diagnosis and MRI findings. Data analyses were performed through descriptive statistics and contingency tables.

RESULTS

Analysis on agreement between clinical diagnosis and MRI findings produced a CDA of 74.5% (108/145) for PTs, 80.8% (139/172) for OSs, and 35.4% (86/243) for NOPs. There was a significant difference in CDA between PTs and NOPs (P<.001), and between OSs and NOPs (P<.001). There was no difference in CDA between PTs and OSs (P>.05).

CONCLUSIONS

Clinical diagnostic accuracy by PTs and OSs on patients with musculoskeletal injuries was significantly greater than for NOPs, with no difference noted between PTs and OSs.

Peripheral arterial disease: therapeutic confidence of CT versus digital subtraction angiography and effects on additional imaging recommendations

PURPOSE

To compare multi-detector row computed tomographic (CT) angiography and digital subtraction angiography (DSA) prior to revascularization in patients with symptomatic peripheral arterial disease for the purpose of assessing recommendations for additional imaging and physician confidence ratings for chosen therapy.

MATERIALS AND METHODS

In a randomized controlled trial, 73 patients were assigned to CT angiography, and 72 were assigned to DSA. Physician confidence in the treatment decision was measured as a continuous outcome on a scale of 0-10 (uncertain to certain) and as a dichotomous outcome (further imaging recommended, yes or no). Mean confidence scores and additional imaging recommendations were compared between CT and DSA groups in an intention-to-diagnose-and-treat analysis. To detect trends in confidence, confidence scores were plotted over time, and multiple linear regression analysis was performed. To detect trends in additional imaging recommendations, logistic regression analysis was used. Data from eligible nonrandomized patients were analyzed separately.

RESULTS

No statistically significant difference in baseline characteristics between randomized groups was found. CT had a lower confidence score than did DSA (7.2 vs 8.2, P < .001). Further imaging was recommended more often after CT (25 of 71 patients, 35%) than after DSA (nine of 66 patients, 14%; P = .003). Analysis of trends demonstrated increasing (but not statistically significant) confidence in CT and stable confidence in DSA. No significant difference was found in baseline characteristics between randomized and nonrandomized patients. Among nonrandomized patients, no significant difference in mean confidence score (8.2 vs 8.3, P = .26) was found between CT (n = 24) and DSA (n = 26).

CONCLUSION

With CT angiography, physician confidence decreases with an associated increase in additional imaging prior to revascularization in patients with symptomatic peripheral arterial disease. Given that CT is less invasive than DSA, results suggest that CT may replace DSA in selected cases.

Patients with suspected meniscal tears: prevalence of abnormalities seen on MRI of 100 symptomatic and 100 contralateral asymptomatic knees

OBJECTIVE

The purpose of this study was to evaluate the prevalence of MR abnormalities of the knee on the symptomatic and contralateral asymptomatic sides in patients with suspected meniscal tears. SUBJECTS AND METHODS. One hundred patients (mean age, 42.7 years; range, 18-73 years) referred for suspected meniscal tears were prospectively examined with MRI of both knees when the contralateral knee was asymptomatic. The prevalence of various types of meniscal tears and other MR abnormalities was determined.

RESULTS

Meniscal tears were found in 57 symptomatic knees and in 36 contralateral asymptomatic knees. In those 57 patients with a meniscal tear on the symptomatic side, the prevalence of asymptomatic tears in the contralateral side was 63% (36/57). Horizontal or oblique meniscal tears were found medially in 32 and laterally in 11 symptomatic knees, and medially in 29 and laterally in eight asymptomatic knees. Radial, vertical, complex, or displaced tears were found medially in 18 and laterally in five symptomatic knees, and medially in five and laterally in none of the asymptomatic knees. Collateral ligament abnormalities were found in 53 symptomatic knees and in six asymptomatic knees. Pericapsular soft-tissue abnormalities were found in 64 symptomatic and in 12 asymptomatic knees. Edema-like bone marrow abnormalities were found in 36 symptomatic and in three asymptomatic knees.

CONCLUSION

Horizontal or oblique meniscal tears are frequently encountered in both asymptomatic and symptomatic knees and may not always be related to symptoms. However, radial, vertical, complex, or displaced meniscal tears and abnormalities of the collateral ligaments, pericapsular soft tissues, and bone marrow are found almost exclusively on the symptomatic side and appear to be clinically more meaningful.

Trends in knee magnetic resonance imaging

OBJECTIVE

To assess trends in knee magnetic resonance imaging (MRI) use and accompanying management changes to determine whether indications for this test have changed over time.

DATA SOURCES

Large administrative database containing health care information for 587,010 people living in 1 state who were enrolled in the Medicare or Medicaid programs. They all had used health services during 3 consecutive years between 1991 to 1995.

METHODS

We performed a retrospective cohort study examining the rates of lower extremity MRI in successive years and calculated the proportion of patients who were seen by a knee specialist or underwent knee surgery subsequent to the MRI.

RESULTS

The annual rate of knee MRI was 1.4 per 1000 person-years in 1991 and increased by 140% to 3.4 per 1000 person-years by 1995 (P = 0.001). Approximately half of patients who underwent a knee MRI in 1991 had a diagnosis of internal derangement of the knee in the prior year; this figure dropped to 35% in 1995 (P < 0.001). The percentage of patients undergoing a knee MRI who had no record of any knee diagnosis in the prior year grew from 13% in 1991 to 33% in 1995 (P < 0.001). Over the 5 years of the study, the percentage of patients whose knee MRI was followed by specialist care or knee surgery decreased from 68% to 58%, a relative change of 15% (P < 0.005).

CONCLUSION

Knee MRI use increased sharply during the study period, but the proportion of such patients who had a prior diagnosis of internal derangement or subsequently saw a knee specialist or underwent knee surgery decreased. This finding indicates that the criteria for knee MRI appear to have broadened substantially during this period.

Acute traumatic hemarthrosis of the knee. Is routine arthroscopic examination necessary? A study of 320 consecutive patients

BACKGROUND AND AIMS

Distortions and contusions of the knee are common. Fairly often they will result in hemarthrosis. The purpose of this study was to evaluate the findings in patients with acute traumatic hemarthrosis of the knee and based on these findings estimate the necessity of acute arthroscopic examination.

MATERIAL AND METHODS

A total of 320 patients were examined arthroscopically between the years 1994 to 96 in the Turku University Hospital. Patients with other than chondral or osteochondral fractures were excluded.

RESULTS

The most common arthroscopic findings were rupture of the ACL (45%), dislocation of the patella (23%) and meniscal tear (21%). In only 113 (35%) cases an immediate therapeutic procedure was performed in addition to the arthroscopic examination.

CONCLUSIONS

Based on our findings we believe that routine arthroscopic examination is not necessary in patients with acute traumatic hemarthrosis of the knee. In our opinion the patient should be examined and followed by an orthopedic surgeon and if a lesion requiring operative treatment is diagnosed or suspected, an arthroscopic examination should be scheduled. The timing of the procedure should be such that all possible lesions encountered can be treated in the same operation.

The effect of pelvic MR imaging on the diagnosis and treatment of women with presumed symptomatic uterine fibroids

PURPOSE

To determine if magnetic resonance (MR) imaging significantly alters the diagnostic thinking and treatment plans of interventional radiologists during the evaluation of women for uterine fibroid embolization (UFE) for presumed uterine fibroids.

MATERIALS AND METHODS

At a single institution, interventional radiologists prospectively completed questionnaires (n = 60) before and after MR imaging was performed in their evaluation of women presenting for potential UFE. The questionnaires asked these physicians the probability (0%-100%) of their most likely diagnosis before MR imaging and after receiving the MR imaging information. They were also asked their anticipated and final treatment plans. Diagnostic confidence gains and the proportion of patients with changed initial diagnoses or anticipated management were calculated. The Wilcoxon signed-rank test was used to assess gains in diagnostic confidence.

RESULTS

MR imaging caused a mean gain in diagnostic confidence of 22% (P <.0001). MR imaging changed initial diagnoses in 11 patients (18%). Immediate clinical management changed in 13 patients (22%). UFE was not performed in 11 of 57 women (19%) who were anticipated before MR imaging to receive UFE.

CONCLUSIONS

MR imaging significantly alters the diagnoses and treatment plans of interventional radiologists evaluating women with presumed symptomatic fibroids. MR imaging should be considered in all patients before UFE.

Clinical decision making in the acutely injured knee based on repeat clinical examination and MRI

To determine the correlation between Magnetic Resonance Imaging (MRI) and clinical examination of the knee after an acute injury, and to see to what extent MRI affected the planned treatment, we examined 90 consecutive patients in a prospective study, clinically and with an extremity Magnetic Resonance (MR) scanner. The number of meniscal lesions, bone bruises and osteochondral lesions found on MRI was significantly higher than the clinical examinations indicated. Despite this, the treatment was only changed in 6 cases. In no case did MRI prevent a planned arthroscopy. MRI may reveal many clinically silent changes in the knee, also after minor injuries. The significance of these MRI findings must await long-term follow-up.

The use of MRI scan of knee injuries in an emergency department

We present a retrospective study of the number of arthroscopically verified total meniscus and cruciate ligament tears seen in our Emergency department one year before, and one year after introducing magnetic resonance imaging (MRI) as a diagnostic tool. The number of total ruptures of the anterior cruciate ligament increased from 34 (1.7% of total 2003 patients) to 67 (2.9% of total 2277). The number of ruptures of the medial meniscus increased from 42 (2.1%) to 87 (3.8%). The number of ruptures of the lateral meniscus remained unchanged. In the first 12 months after introducing MRI we ordered 513 (23%) scans of the total number of 2277 patients with an acute knee condition. Thirty-nine (8%) of these were described with no pathology, 227 (44%) showed total meniscus or cruciate ligament tears. The remaining 247 (48%) were mainly degenerative or partial injuries. The cost per additional new diagnosis was approximately USD 800. The introduction of MRI has enabled us to identify a larger number of patients with meniscus and cruciate ligament injuries.

Magnetic resonance imaging of the knee

Magnetic resonance imaging (MRI) has revolutionised diagnostic imaging of the knee. It has evolved significantly since Kean described healthy and pathologic knee anatomy in 1983. This innovative technology allows superior soft-tissue detail with multiplanar imaging capability that provides accurate evaluation of intra- and extra-articular structures of the knee not demonstrated with other imaging modalities. The development and advancements in MRI and the introduction of high-resolution coils have provided a noninvasive, nonoperator dependent, cost effective means to diagnose knee pathology. MRI is well tolerated by patients, widely accepted by evaluating physicians, and assists in distinguishing pathologic knee conditions that may have similar clinical signs and symptoms (i.e. meniscal tears, osteochondral lesions). This paper presents an overview of MRI of the knee and focuses on the MRI findings in a number of common pathologic conditions.

Imaging of sports-related knee injuries

This article reviewed the major sports medicine conditions affecting the knee and their MR imaging appearance. MR imaging of the knee is considered efficacious especially in the setting of indeterminate clinical findings and can stratify patients, guiding further surgical management. MR imaging affects the diagnosis and management of acute knee injury by improving clinician diagnostic certainty, assisting in management decisions, and decreasing the number of arthroscopic procedures. From a societal perspective, knee MR imaging can be considered a cost-effective modality when compared with diagnostic and borderline therapeutic arthroscopies (e.g., debridement alone). For these and other reasons, knee MR imaging has shown a substantially increased use for the evaluation of sports medicine conditions.

Comparison of knee magnetic resonance imaging findings in patients referred by orthopaedic surgeons versus nonorthopaedic practitioners

PURPOSE

To compare the percentages of normal magnetic resonance imaging (MRI) examination results and clinically significant knee abnormalities in patients referred for MRI of the knee by orthopaedic surgery residents and staff with those of patients referred by nonorthopaedic practitioners.

TYPE OF STUDY

Retrospective review of MRI findings.

METHODS

MRI reports of 754 patients (454 men and 300 women) were retrospectively reviewed; 373 patients were referred from the Department of Orthopaedic Surgery and 381 patients were referred from nonorthopaedic practitioners. The number of normal examination results, meniscal and ligament tears, chondral abnormalities, and Baker's cysts was tabulated and analyzed using a X-square injury analysis.

RESULTS

The rate of normal results for nonorthopaedic practitioners was 33.9% (129 of 381) compared with 15.3% (57 of 373) for orthopaedic surgeons (P <.001). Nonorthopaedic surgeons referred 69.4% (129 of 186) of the patients who had normal examination results. The positive finding for a lateral meniscus tear was 29.2% (109 of 373) for orthopaedic surgeons compared with 19.1% (73 of 381) for nonorthopaedic practitioners, which was statistically significant (P =.002) in regard to the distribution of injuries. No difference was found in other abnormalities assessed.

CONCLUSIONS

Patients referred by nonorthopaedic practitioners had significantly more normal knee MRI examination results than did those referred by orthopaedic surgeons.

Effect of MR angiography on the diagnosis and treatment of patients with suspected renovascular disease

PURPOSE

Although the diagnostic accuracy of renal magnetic resonance (MR) angiography is established, its effect on referring physicians is unknown. The authors prospectively measured the effect of MR angiography results on referring physicians' diagnosis and treatment (plans) of patients with suspected renovascular disease.

MATERIALS AND METHODS

Referring physicians prospectively completed questionnaires before and after MR angiography was performed during evaluation of their patients with suspected renovascular disease. The questionnaires asked them to estimate the probability (0%-100%) of their most likely diagnosis before and after receiving the imaging information. They were also asked for their anticipated and final treatment plans. The authors calculated the mean gain in diagnostic percentage confidence and the proportion of patients with changed initial diagnoses or anticipated management. A paired t-test was used to assess significance of the gains in diagnostic percentage confidence.

RESULTS

Physicians prospectively completed pre- and post-MR-angiography questionnaires for 30 patients. MR angiography improved mean diagnostic certainty by 35% (P < .0001). MR angiography changed physicians' initial diagnoses in 12 patients (40%). Anticipated treatment plans were changed in 20 patients (67%). Invasive procedures were avoided in eight patients (27%).

CONCLUSION

MR angiography has a substantial effect on the diagnostic and therapeutic decision-making of physicians managing patients with suspected renovascular disease.

Impact of MR angiography on the diagnosis and management of renal transplant dysfunction

PURPOSE

To evaluate the impact of magnetic resonance angiography (MRA) on referring physicians' diagnoses and treatment of patients with renal transplant dysfunction.

MATERIALS AND METHODS

Physicians of the renal transplant service at the authors' university hospital prospectively completed questionnaires before and after MRA was performed in the evaluation of renal transplants. The questionnaires asked physicians to estimate the probability (0%-100%) of their most likely diagnosis before and after receiving the imaging information. They were also asked to provide their anticipated and final treatment plans. The authors calculated the mean gain in diagnostic percentage confidence and the proportion of patients with changed initial diagnoses or anticipated management. A paired t test was used to assess statistical significance of the gains in diagnostic percentage confidence.

RESULTS

Pre-MRA and post-MRA questionnaires were prospectively completed on 31 separate patients. The mean gain in diagnostic certainty percentage from MRA was 33% (95% CI, 19%-51%; P < .001). MRA changed physicians' initial diagnoses in 20 patients (65%; 95% CI, 47%-79%). Immediate clinical management changed in 16 patients (52%; 95% CI, 35%-68%). Invasive procedures were avoided in 12 patients (39%).

CONCLUSION

MRA has considerable impact on referring physicians' diagnoses and treatment of patients with suspected renal allograft dysfunction.

Morton neuroma: effect of MR imaging findings on diagnostic thinking and therapeutic decisions

PURPOSE

To determine the effect of magnetic resonance (MR) imaging results on diagnostic thinking and therapeutic decisions by orthopedic surgeons in cases of a possible Morton neuroma.

MATERIAL AND METHODS

Orthopedic surgeons completed a questionnaire before and after MR imaging for 54 feet in 49 patients thought to have Morton neuroma. Clinical diagnosis (Morton neuroma, differential diagnosis), location, diagnostic confidence, and therapeutic decisions were noted before and after MR imaging. The influence of the size of the neuroma on therapeutic decisions was analyzed. MR imaging diagnoses were compared with surgical results for 23 revised intermetatarsal spaces.

RESULTS

After MR imaging, the clinical diagnosis of Morton neuroma was withdrawn in 15 of 54 (28%) feet. In 14 of 39 maintained diagnoses, the location or number of neuromas was changed after MR imaging. Confidence levels for Morton neuroma increased substantially after MR imaging. In 31 (57%) feet, a change in treatment plan resulted after MR imaging. Diameters of neuromas on MR images were significantly larger (P = .003) in surgically treated feet than in conservatively treated feet. MR imaging diagnoses were correct in all 23 revised intermetatarsal spaces.

CONCLUSION

MR imaging has a major effect on diagnostic thinking and therapeutic decisions by orthopedic surgeons when Morton neuroma is suspected, especially because MR imaging helps in localization and size assessment of Morton neuromas.

A critical synopsis of the diagnostic and screening radiology outcomes literature

In summary, the radiology outcomes research literature is both extensive and broad. The methodologic quality, however, is quite variable. Overall, this quality could be improved by intervention in two areas: methodologic dissemination and development. The number of researchers investigating radiology-related outcomes is high, and presently there are over 20 journals devoted exclusively to radiology research. Even with a relatively narrow definition of "outcomes," we identified over 200 radiology outcomes studies, most from the past few years. However, the methodologic quality of most of these articles was relatively low, with important design flaws and biases. Nonetheless, a substantial number of radiology publications do employ state-of-the-art research methods and innovative approaches to methodologic challenges. The quality of radiology outcomes research overall would benefit tremendously from dissemination of such research methods. Instruction in outcomes research methods is accessible to radiologists. For example, there have been several recent articles and series of articles on outcomes research methods in JAMA, including guidelines for the performance and reporting of cost-effectiveness analyses (38-40) and for developing clinical prediction rules (57). Within radiology, several recent articles have appeared on, among other things, cost-effectiveness analysis (34,59,60), assessing quality of life (43), screening for disease (53), and defining the study population (61). The research compendium compiled for the GERRAF (General Electric-Association of University Radiologists Radiology Research Academic Fellowships) program remains a comprehensive methodologic source for many of the issues in radiology outcomes research, and outcomes research methods courses are offered every year at the Society for Health Services Research in Radiology and Society for Medical Decision Making meetings, as well as at the meeting of the Radiological Society of North America. Even so, awareness of the need for such research techniques remains limited. Dissemination of sound research methods is limited at least in part by the current incentives in radiology research. At many institutions, the number of research publications produced, rather than their quality, determines promotion or academic success. Unfortunately, more rigorous study designs often require more time and resources. Further, because peer reviewers are often as uninformed about research methods as the bulk of those who are submitting manuscripts, it may actually be more difficult to publish articles with more advanced methodologic designs. The standard in radiology is the uncontrolled case series, and deviation from the standard may make acceptance for publication more difficult. On a more optimistic note, recent publication of a number of methodology articles suggests that at least some journals are promoting improved research in methodology (43,53,59-61). We hope that time will be available for manuscript reviewers to learn to understand the strengths and weaknesses of various research approaches. If more rigorous study designs were required for publication, radiology outcomes research would probably improve drastically. Nevertheless, the current peer-review system does not effectively promote sound research design. The other great incentive in research is funding. Clearly, if advanced research design is required for funding, then there is incentive for improvement in research quality. Traditionally, National Cancer Institute and other National Institutes of Health and public sector funding has been predicated on a high level of research sophistication. Undoubtedly, availability of grants for diagnostic and screening imaging clinical trials and other research will go far to improve radiology research methods. The other traditional source of research funding is industry.