Structural analysis and magnetic resonance imaging predict plaque vulnerability: a study comparing symptomatic and asymptomatic individuals

BACKGROUND: More than half of all cerebral ischemic events are the result of rupture of extracranial plaques. The clinical determination of carotid plaque vulnerability is currently based solely on luminal stenosis; however, it has been increasingly suggested that plaque morphology and biomechanical stress should also be considered. We used finite element analysis based on in vivo magnetic resonance imaging (MRI) to simulate the stress distributions within plaques of asymptomatic and symptomatic individuals. METHODS: Thirty non-consecutive subjects (15 symptomatic and 15 asymptomatic) underwent high-resolution multisequence in vivo MRI of the carotid bifurcation. Stress analysis was performed based on the geometry derived from in vivo MRI of the carotid artery at the point of maximal stenosis. The finite element analysis model considered plaque components to be hyperelastic. The peak stresses within the plaques of symptomatic and asymptomatic individuals were compared. RESULTS: High stress concentrations were found at the shoulder regions of symptomatic plaques, and the maximal stresses predicted in this group were significantly higher than those in the asymptomatic group (508.2 +/- 193.1 vs 269.6 +/- 107.9 kPa; P = .004). CONCLUSIONS: Maximal predicted plaque stresses in symptomatic patients were higher than those predicted in asymptomatic patients by finite element analysis, suggesting the possibility that plaques with higher stresses may be more prone to be symptomatic and rupture. If further validated by large-scale longitudinal studies, biomechanical stress analysis based on high resolution in vivo MRI could potentially act as a useful tool for risk assessment of carotid atheroma. It may help in the identification of patients with asymptomatic carotid atheroma at greatest risk of developing symptoms or mild-to-moderate symptomatic stenoses, which currently fall outside current clinical guidelines for intervention.     

Lumbar discography in normal subjects. A controlled, prospective study

Major advances in the techniques of discography since 1968, in conjunction with major strides in the evaluation of pain in recent years, prompted a study in which Holt's work on the specificity of discography was replicated and extended. For the present study, seven patients who had low-back pain and ten volunteers who had been carefully screened, with a questionnaire and a physical examination, to ensure that they had no history of problems with the back, had an injection at three levels, and all sessions were videotaped. After each injection, the participant was interviewed about the pattern and intensity of the pain, and then the discs were imaged with computed tomography. Five raters, who were blind to the condition of the participant, graded each disc as normal or abnormal on the basis of findings on magnetic resonance images that had been made before the injection and computed tomography (discography) were done. There was only one disagreement between the ratings that were made on the basis of the magnetic resonance images and those that were made on the basis of the discograms. Each participant's pain-related response was evaluated independently by two raters who viewed the videotapes of the discography. Inter-rater reliability was 0.99, 0.93, and 0.88 for the evaluation of intensity of the pain, pain-related behavior, and similarity of the pain to pain that the subject had had before the injection. In the asymptomatic individuals, the discogram was interpreted as abnormal for 17 per cent (five) of the thirty discs and for five of the ten subjects.(ABSTRACT TRUNCATED AT 250 WORDS)     

Age-related magnetic resonance imaging morphology of the menisci in asymptomatic individuals

In 82 asymptomatic subjects aged 8–62 years we evaluated the menisci by magnetic resonance imaging (MRI). Using a 1.0-tesla imager spin-echo sequences (SE 700/20), partial-saturation sequences (500/10), and short-time inversion-recovery sequences (1600/130/30) were performed. For grading the degeneration of the meniscus, a standard classification (grades 0–4) was used. Positive MRI findings correlated with the patients' age. In SE sequences, a grade 0 meniscus was found in 45.5% of all cases, grade 1 in 33.2%, grade 2 in 16.1%, grade 3 in 4.5%, and grade 4 in 0.7%. In PS sequences, we found grade 0 in 23.9%, grade 1 in 27.5%, grade 2 in 31.5%, grade 3 in 15.9%, and grade 4 in 1.1 %. In STIR sequences, we found grade 0 in 56%, grade I in 25.4%, grade 2 in 11.1%, grade 3 in 6%, and grade 4 in 1.6%. Correlation of meniscus degeneration with subjects' age showed an increase of grade 3 and 4 lesions with advancing age. Subjects older than 50 years presented with grade 3 and 4 lesions in the SE sequence in 28.5% of the cases, in PS sequences in 40.7%, and in STIR sequences in 25%. In asymptomatic subjects, MRI shows an increasing prevalence of meniscal alterations which correlates with age. Especially in subjects older than 50 years, a significant number of meniscal tears must be expected. This shows the potential danger of the use of MRI alone as a basis for the determination of surgical intervention.     

Tissue characterization of symptomatic and asymptomatic disc herniations by quantitative magnetic resonance imaging

The purpose of this investigation was to determine differences in tissue composition of symptomatic and asymptomatic disc herniations as reflected in T₁ and T₂ relaxation times (quantitative magnetic resonance investigation of the lumber spine. The longitudinal and transverse magnetic rlaxation times (T₁ and T₂, respectively) were calculated from a set of 20 images obtained with five single-slice/multi-echo sequences at different repetition time values on a commercial whole-body system (1.5 T). Twenty-two symptomatic and asymptomatic disc herniations could be matched according to age, gender, disc level, and the extent of herniation (protrusion or extrusion) and were compared with regard to T₁ and T₂ relaxation times. Symptomatic disc herniations exhibited significantly (p_T1 < 0.04 and p_T2 < 0.003) shorter T₁(ΔT₁:–182.1 milliseconds, ?15%) and T₂(ΔT₂: ?11.0 milliseconds, ?21%) relaxation times than matched asymptomatic herniations. Symptomatic disc herniations also exhibited more advanced disc degeneration as graded by Pearce's criteria (p < 0.01). These results suggest that symptomatic and morphologically matched asymptomatic disc herniations differ with regard to disc matrix composition.     

A comparison of magnetic resonance imaging findings of the acromioclavicular joint in symptomatic versus asymptomatic patients

The purpose of this study was to compare acromioclavicular (AC) joint magnetic resonance imaging (MRI) findings in asymptomatic patients with those in symptomatic patients. The MRI scans of 25 patients with symptomatic AC joints were compared with 50 asymptomatic control subjects by use of the same grading scale. In the symptomatic group, AC joint arthritis grading was normal in 0%, mild in 20%, moderate in 52%, and severe in 28%. In the asymptomatic group, grading was normal in 18%, mild in 66%, moderate in 12%, and severe in 4%; there was a statistically higher grade of AC arthritis in the symptomatic group (P < .05). Of the symptomatic individuals, 80% demonstrated reactive bone edema in either the distal clavicle (6), the acromion (3), or both sides of the AC joint (11), whereas no individual in the asymptomatic group had this finding (P < .05). Reactive bone edema on MRI is a more reliable predictor of symptomatic AC pathology than degenerative changes seen on MRI and, when correlated with clinical examination, is reproducible.     

A prospective and blinded investigation of magnetic resonance imaging of the knee. Abnormal findings in asymptomatic subjects.

To evaluate magnetic resonance imaging (MRI) of meniscal, ligamentous, and bony abnormalities in patients without clinical symptoms, scans were performed on 74 asymptomatic volunteers without histories or symptoms of knee injury. Before review by three radiologists in an independent and blinded fashion, the scans were mixed with 26 MRI scans from symptomatic patients. Sixteen percent of the asymptomatic volunteers had meniscal abnormalities consistent with a tear. The prevalence of MRI findings of a meniscal tear increased from 13% in individuals younger than 45 years of age to 36% in those older than 45. An additional 30% of the volunteers showed meniscal abnormalities consisting of a linear area of increased MR signal not communicating with a meniscal edge, which was not interpreted to represent a tear. The high incidence of abnormal MRI findings in asymptomatic subjects underscores the danger of relying on a diagnostic test without careful correlation with clinical signs and symptoms. These findings also emphasize the importance of access to relevant clinical data when interpreting MRI scans of the knee.     

Provocative discography in patients after limited lumbar discectomy: A controlled, randomized study of pain response in symptomatic and asymptomatic subjects

STUDY DESIGN: This was a prospective observational study of patients with low back pain and those without after laminotomy and discectomy. OBJECTIVES: To determine, using a strict experimental design, the relative pain intensity response to provocative discography in symptomatic and asymptomatic subjects after lumbar discectomy for intervertebral disc herniation. BACKGROUND: Provocative discography frequently is used to evaluate persistent or recurrent low back pain syndromes in patients who have undergone posterior discectomy. The validity of interpreting painful injections during this procedure has not been critically assessed. The prevalence of significantly painful disc injections in a group with good outcomes after surgery is not known. Knowing the rates of significantly painful injections in asymptomatic patients after lumbar discectomy may clarify the meaning of painful injections in symptomatic patients. METHODS: From a cohort of 240 patients who had undergone single-level limited discectomy for sciatica, 20 asymptomatic volunteers were recruited for experimental three-level lumbar discography. Inclusion criteria required nearly perfect scores on standardized back pain rating instruments, no other spinal pathology, and normal psychometric screening. A control group of 27 symptomatic patients, after single-level discectomy with intractable low back pain syndrome, and without other spinal pathology, underwent discography. Seven patients in the control group had normal psychometric tests. Experienced raters who were blinded to control versus experimental status of the subjects scored the magnetic resonance imaging, discogram, psychometric tests, and discography videotapes of the subjects' pain behavior. RESULTS: There were 8 of 20 (40%) positive injections of discs that had previous surgery in the asymptomatic group and 17 of 27 (63%) positive injections in the symptomatic group. Specifically with regard to the symptomatic group, there were 3 of 7 (43%) positive injections (all concordant) in patients with normal psychometric scores, as compared with 14 of 20 (70%) positive injections (12 concordant) in patients with abnormal psychometric scores. Injections of discs that had previous surgery resulted in a mean pain score of 2.1 of 5 in the asymptomatic group, 2.1 in the symptomatic group with normal psychometric scores, and 3.4 in the symptomatic group with abnormal psychometric scores. Of the discs not treated with surgery, 2 were positive in the asymptomatic group (10%), 3 in 2 symptomatic subjects with normal psychological testing (29), and 18 in 13 symptomatic subjects with abnormal psychometric testing (76%). CONCLUSIONS: A high percentage of asymptomatic patients with normal psychometric testing who previously have undergone lumbar discectomy will have significant pain on injection of their discs that had previous surgery (40%). This is not significantly different from the experience of symptomatic patients with normal psychometric testing undergoing discography on discs that had previous surgery. Patients with abnormal psychological profiles have significantly higher rates of positive disc injections than either asymptomatic volunteers or symptomatic subjects with normal psychological screening.     

A cadaveric study comparing discography, magnetic resonance imaging, histology, and mechanical behavior of the human lumbar disc.

The aims of this study were 1) to compare discography and magnetic resonance imaging scanning on cadaver specimens and to correlate these imaging procedures by examining all the discs histologically; and 2) to study the extent to which the amplitude of rotational movement in the neutral and flexed position at a certain level correlates with the morphologic appearance of that disc. Twenty-four human lumbar spines were harvested from cadavers between the ages of 19 and 75 years. Each specimen underwent standard radiography, magnetic resonance imaging scanning, discography, histologic examination, and measurement of axial rotation in a torsion apparatus. For practical reasons, all specimens did not undergo all of the examinations. Not all peripheral anular lesions were detected by discography. Histology showed rim lesions of the anterior anulus in 18% of discs with normal discography. The overall incidence of anterior and posterior anular tears was greater in discs where larger amplitudes of rotation were observed. To which extent the one is a consequence of the other or vice versa is not clear. Magnetic resonance imaging was found to be less specific than discography. However, it must be emphasized that no axial magnetic resonance imaging scans were taken in this study. Discs with significantly decreased amounts of nuclear material (observed at histology) can still produce normal magnetic resonance imaging images. Infolding of the inner layers of the anulus fibrosus (33% anterior, 4% posterior) was a frequently observed feature.     

Axially loaded magnetic resonance image of the lumbar spine in asymptomatic individuals.

STUDY DESIGN: For this study, 43 asymptomatic individuals underwent magnetic resonance imaging of the lumbar spine in both supine psoas-relaxed position and supine axial compression in extension. The change in dural cross-sectional area between positions at each disc level was calculated. OBJECTIVES: To evaluate the effect of axial loading on asymptomatic individuals, as compared with the effect on patients who have clinical signs of lumbar spinal canal stenosis, and to assess the effect that different magnitude and duration of the applied load have on the dural cross-sectional area. SUMMARY OF BACKGROUND DATA: Degenerative changes in the spine are found in both symptomatic and asymptomatic individuals. A study of patients with suspected clinical lumbar spine encroachment examined in both psoas-relaxed position and axial compression in extension with computed tomographic myelography or magnetic resonance imaging of the lumbar spine is reported. A significant decrease in dural cross-sectional area was found, respectively, in 80% and 76% of the patients. METHODS: The study subjects underwent magnetic resonance imaging examinations in both psoas-relaxed position and axial compression in extension. The examination of the subject under axial compression in extension was performed with the lumbar spine in a supine position using a compression device. Degenerative changes in and adjacent to the spinal canal were registered. The dural cross-sectional areas were determined for psoas-relaxed position and axial compression in extension, then compared. In seven reexamined individuals, the dural cross-sectional area was calculated after an axial load corresponding to 25% and 50% of their body weight and a loading time of 5 to 60 minutes. RESULTS: A significant decrease in dural cross-sectional area from psoas-relaxed position to axial compression in extension was found in 24 individuals (56%), most frequently at L4-L5, and increasingly with age. In four individuals (5 disc levels), a decrease in dural cross-sectional area to less than 100 mm2 from psoas-relaxed position to axial compression in extension was found. In seven reexamined individuals, a significant decrease in dural cross-sectional area was found: in five after 5 minutes load of 25% of their body weight, and in two with 50% of their body weight. CONCLUSIONS: Using magnetic resonance imaging, a significant decrease in dural cross-sectional area after axial loading was found less frequently in asymptomatic than in symptomatic subjects. The decrease was more frequent at L4-L5, and increasingly with age. The load should be 50% of the subject's body weight applied for at least 5 minutes.     

Comparison of magnetic resonance imaging and lumbar discography in the diagnosis of disc degeneration

A prospective comparison of 97 discs in 50 patients studied by both magnetic resonance imaging and discography showed a high correlation in the identification of the degenerative disc between these two modalities.     

Magnetic resonance imaging and discography in the diagnosis of disc degeneration. A comparative study of 50 discs

The lumbar spines of 22 patients were examined for disc degeneration by magnetic resonance imaging (MRI) and by discography. The results from 50 intervertebral discs visualised by both techniques were independently assessed and graded on a five-point scale from normality to gross degeneration and then compared. In 44 discs the results agreed. Of the six discs which gave differing results, four discrepancies were due to observer error and two to incorrect placement of the discographic needle. MRI was shown to be more accurate than discography in the diagnosis of disc degeneration. It has several major advantages, which should make it the investigation of choice.     

Detection of acromioclavicular joint pathology in asymptomatic shoulders with magnetic resonance imaging.

The purpose of this study was to determine the prevalence of acromioclavicular joint (ACJ) arthritis with magnetic resonance imaging (MRI) evaluation in asymptomatic patients. Fifty shoulders in 42 patients were evaluated with the use of standard MRI techniques. There were 18 men and 24 women with an average age of 35 years (range, 19 to 72). ACJ arthritic changes were graded on a scale from 1 to 4 (none, mild, moderate, and severe), based on the amount of subacromial fat effacement, joint space narrowing, irregularity, capsular distension, and osteophyte formation. Forty-one (82%) of 50 shoulders had abnormalities consistent with arthritis on MRI. Patients were divided into two groups according to age: those older than 30 years and those 30 years old or younger. In the 30-and-under age group, 68% of the shoulders had arthritic changes, whereas in the over-30 age group, 93% had arthritic changes. Furthermore, in a comparison of the two groups, more advanced arthritic changes were found in the over-30 age group (P <.05). Clinical decisions to resect the ACJ should correlate the physical examination with the MRI findings because many patients may be clinically asymptomatic.     

Popliteal vessels in knee surgery. A magnetic resonance imaging study.

Popliteal artery injury during surgery of the knee is rare but can have devastating consequences. The position of knee flexion has been thought to be protective for the popliteal artery, allowing it to fall back from the knee joint. No prior study has provided in vivo cross sectional evidence of the behavior of the popliteal vessels during knee flexion with the effect of gravity. Magnetic resonance imaging was used in nine volunteers to measure the distance of the popliteal artery and veins from the posterior proximal tibia at two levels corresponding to the levels of osteotomy in total knee arthroplasty and in high tibial osteotomy. Scans were taken with the knee in full extension and at 90 degrees flexion with the patient in the supine position, allowing for the effect of gravity. Considerable variation in behavior of the vein and the artery was observed at the high tibial osteotomy cross sectional level and the total knee arthroplasty cross sectional level. In two knees at the high tibial osteotomy cross sectional level and in two knees at the total knee arthroplasty cross sectional, level the artery moved closer to the posterior tibia with knee flexion. Even with the effect of gravity included, knee flexion does not guarantee removal of the popliteal vessels from potential harm during surgery of the knee.     

Diagnosis of symptomatic disc by magnetic resonance imaging: T2-weighted and gadolinium-DTPA-enhanced T1-weighted magnetic resonance imaging

Although radial tear of the annulus fibrosus can be detected on T2-weighted and Gd-DTPA-enhanced magnetic resonance (MR) images, the association between the annular tear on MR images and the symptomatic discs is unclear. The purpose of this study was to investigate the relationship between T2-weighted, gadolinium-DTPA-enhanced MR images and pain response through discography in patients with chronic low back pain. A total of 56 lumbar discs from 23 patients with chronic low back pain (13 to 47 years old) underwent MR imaging (T2-weighted, gadolinium-DTPA-enhanced MR images) followed by provocative discography. The sensitivity, specificity, positive predictive value, and negative predictive value of T2-weighted and gadolinium-DTPA-enhanced MR images in detecting the symptomatic discs were calculated. The sensitivity, specificity, positive predictive value, and negative predictive value of T2-weighted images in detecting the symptomatic disc were 94%, 71%, 59%, and 97%, respectively. The sensitivity, specificity, positive predictive value, and negative predictive value of gadolinium-DTPA-enhanced images were 71%, 75%, 56%, and 86%, respectively. The high sensitivity and the high negative predictive value of T2-weighted MR imaging in detecting the symptomatic disc indicated that MR imaging can be a useful screening tool in avoiding unnecessary discography in patients with chronic low back pain.     

Glioma-grade diagnosis using in-phase and out-of-phase T1-weighted magnetic resonance imaging: A prospective study

PurposeThe purpose of this prospective study was to determine whether chemical shift gradient-echo magnetic resonance imaging (MRI) could predict glioma grade.Materials and methodsA total of 69 patients with 69 gliomas were prospectively included. There were 41 men and 28 women with a mean age of 50 ± (SD) years (range: 16–82 years). All patients had MRI of the brain including chemical shift gradient-echo sequence, further referred to as in- and out-of phase sequence (IP/OP). Intravoxel fat content was estimated by signal loss ratio (SLR = [IP-OP]/2IP), between in- and out-of-phase images, using a region of interest placed on the viable portion of the gliomas. Association between SLR and glioma grade was searched for using Wilcoxon and Mann–Whitney U tests and diagnostic capabilities using area under the receiver operating characteristic (AUROC) curves.ResultsA significant association was found between SLR value and glioma grade (P < 0.0001). SLR > 9‰ allowed complete discrimination between grade III and grade II glioma with 100% specificity (95% CI: 85–100%), 100% sensitivity (95% CI: 78–100%) and 100% accuracy (95% CI: 90–100%) (AUROC = 1). A SLR > 20‰ allowed discriminating between grade IV and grade III glioma with 75% specificity (95% CI: 57–89%), 73% sensitivity (95% CI: 45–92%) and 72% accuracy (95% CI: 57–84%) (AUC = 0.825, 95% CI: 0.702–0.948). The AUROC for the diagnosis of high-grade glioma (grade III and IV vs. grade II) was 1.ConclusionChemical shift gradient echo MRI provides accurate grading of gliomas. This simple method should be used as a biomarker to predict glioma grade.     

A prospective study of preoperative and postoperative sequential magnetic resonance imaging and early clinical outcome in automated percutaneous lumbar discectomy.

The authors evaluated the size of the disc herniation with magnetic resonance imaging (MRI) before and after surgery in patients undergoing automated percutaneous lumbar discectomy (APLD) and compared the MRI findings with the early clinical outcome. This study includes 20 consecutive patients with a contained lumbar disc herniation. Sequential MRI were performed immediately before and after surgery, on the day of surgery, and 6 weeks after surgery. The development of pain, nerve root tension sign (SLR), and neurological findings were analyzed, as was the need for subsequent open surgery. There was no significant difference in the maximum protrusion of the disc herniation between the three measurements. The sciatic pain improved significantly on the first day after surgery but not at 1 week or 6 weeks after surgery. The SLR was reduced significantly after surgery and at 1 and 6 weeks after surgery. There was no correlation between the MRI findings and the early clinical outcome. Seven patients needed subsequent open surgery. The findings indicate that the effect of APLD is not mediated by reducing the size of the disc herniation. In this small series of patients, APLD was ineffective in the treatment of a contained lumbar disc herniation. There was no correlation between the MRI findings and the early clinical outcome.     

Abnormal findings on knee magnetic resonance imaging in asymptomatic NBA players

The purpose of this study was to evaluate the knees of asymptomatic National Basketball Association (NBA) players via magnetic resonance imaging (MRI) and confirm or dispute findings reported in the previous literature. It is thought that a variety of significant abnormalities affecting the knee exist in asymptomatic patients and that these findings can be accurately identified on MRI. Two months prior to the 2005 season, bilateral knee MRI examinations of 14 asymptomatic NBA players (28 knees) were evaluated for abnormalities of the articular cartilage, menisci, and patellar and quadriceps tendons. The presence of joint effusion, subchondral edema, and cystic lesions and the integrity of the collateral and cruciate ligaments were also assessed.