Biomedical subjects

Mark E Schweitzer

Publications and source records attributed to Mark E Schweitzer.

At least 19 recordsLinked to original sources

PubMed2006

Calculation of rotational deformity in pediatric supracondylar humerus fractures.

OBJECTIVE: Supracondylar humerus fractures (SCHF) are common in the pediatric population. Cubitus varus deformity (CVD) is the most common long-term complication of SCHFs and may lead to elbow instability and deficits in throwing or extension. Distal fragment malrotation in the axial plane disposes to fragment tilt and CVD; however, no simple method of assessing fracture malrotation exists. This study tested a mathematical method of measuring axial plane malrotation in SCHFs based on plain radiographs. DESIGN: A pediatric SCHF model was made, and x-rays were taken at known intervals of rotation. Five independent, blinded observers measured these films. Calculated rotation for each data set was compared to the known rotation. The identical protocol was performed for an aluminum phantom. RESULTS: The reliability and agreement of the rotation values were good for both models. CONCLUSIONS: This method is a reliable, accurate, and cost-effective means of calculating SCHF distal fragment malrotation and warrants clinical application.

Child↗

PubMed2006

High-signal T2 changes of the bone marrow of the foot and ankle in children: red marrow or traumatic changes?

BACKGROUND: High-signal T2-weighted bone marrow changes can be found in both bone marrow edema and hematopoietic marrow and are often seen on pediatric MR images of the feet and ankle. OBJECTIVE: To evaluate whether high-signal T2 changes of the bone marrow seen on pediatric MRI of feet and ankles represent residual hematopoietic marrow. MATERIALS AND METHODS: A total of 402 bones in 41 pediatric MRI studies of feet and ankles (34 children, 1-18 years) were reviewed by two observers who were blinded to the patients' ages. The studies were reviewed for the presence of high-signal changes of the bone marrow on sagittal fluid-sensitive images. The frequency and location of these foci were correlated with the patients' ages. RESULTS: High-signal T2 changes of the bone marrow were seen in 45/402 bones (11%) and in 24/41 patients younger than 16 years (59%). The changes were most commonly located in the calcaneus (54%), followed by the talus (35%) and navicular bone (35%), invariably at the endosteal surface. In 16 ankles, such foci were seen in the feet but not in the distal tibia/fibula. Symmetric presence (two ankles) or absence (four ankles) of high-signal marrow were seen in six of seven patients with bilateral ankles. CONCLUSION: High-signal T2 changes of the bone marrow in pediatric feet and ankle MRIs have a symmetric, fairly consistent pattern and disappear after the age of 15 years. We believe that these high-signal areas are normal and represent residual hematopoietic marrow.

Adolescent↗

PubMed2006

Posterior longitudinal ligament status in cervical spine bilateral facet dislocations.

OBJECTIVE: It is generally accepted that cervical spine bilateral facet dislocation results in complete disruption of the posterior longitudinal ligament. The goal of this study was to evaluate the integrity of numerous spine-stabilizing structures by MRI, and to determine if any associations between injury patterns exist with respect to the posterior longitudinal ligament status. DESIGN: Retrospective case series. PATIENTS: A retrospective review was performed of 30 cervical spine injury subjects with bilateral facet dislocation. Assessment of 1.5T MRI images was carried out for: intervertebral disc disruption, facet fracture, and ligamentous disruption. Statistical analyses were performed to evaluate for associations between various injury patterns and posterior longitudinal ligament status. RESULTS: The frequency of MRI abnormalities was: anterior longitudinal ligament disruption (26.7%), disc herniation or disruption (90%), posterior longitudinal ligament disruption (40%), facet fracture (63.3%) and disruption of the posterior column ligament complex (97%). There were no significant associations between injury to the posterior longitudinal ligament and other structures. Compared to surgical reports, MRI was accurate for determining the status for 24 of 26 ligaments (three of three anterior longitudinal ligament, seven of nine posterior longitudinal ligament, and 14 of 14 posterior column ligament complex) but generated false negatives in two instances (in both MRI showed an intact posterior longitudinal ligament that was torn at surgery). CONCLUSIONS: In contradistinction to the existing concept, the posterior longitudinal ligament can remain intact in a substantial proportion of hyperflexion injuries that produce bilateral cervical facet dislocation. Posterior longitudinal ligament integrity is not associated with any other injury pattern related to the anterior longitudinal ligament, intervertebral disc or facet fracture.

Adult↗

PubMed2006

Shoulder impingement: objective 3D shape analysis of acromial morphologic features.

PURPOSE: To retrospectively and quantitatively analyze the acromial undersurface in three dimensions and to determine its association with impingement syndrome and rotator cuff tears. MATERIALS AND METHODS: Institutional review board approval was received with exemption of informed consent for this retrospective HIPAA-compliant study. Magnetic resonance images were evaluated in 84 patients (63 males, 21 females; mean age, 42.6 years; age range, 15-74 years). On the basis of surgical results, patients were separated into three groups: those without shoulder impingement or rotator cuff tears (31 patients), those with shoulder impingement (22 patients), and those with rotator cuff tears (31 patients). To quantitate the acromial undersurface, the structure was manually plotted, and a mathematic model was created by using splines. The undersurface was divided into a 20 x 20 grid. For each patient, a shape index (SI) data set and local undersurface angulation (LUA) data set were determined. Regression analyses were used to identify differences between groups, and prediction models were constructed on the basis of correspondent areas. RESULTS: Analysis of both data sets yielded no apparent progression between groups and demonstrated a lack of similarity between the impingement and rotator cuff tear groups. Discrimination between groups could be demonstrated by dividing the lateral portion of the acromial undersurface into contiguous blocks. The highest overall diagnostic accuracy of our prediction models was 58.3% (49 of 84) by using 10 blocks of the SI data set and 73.8% (62 of 84) by using five blocks of the LUA data set. CONCLUSION: Three-dimensional modeling yields objective data about the acromial undersurface. On the basis of this method, osseous impingement by the acromion is not a primary cause of shoulder impingement syndrome or rotator cuff tears.

Acromion↗

PubMed2006

Quadriceps fat pad edema: significance on magnetic resonance images of the knee.

OBJECTIVE: While clinically reading magnetic resonance (MR) images of the knees we have occasionally noted edema within the suprapatellar fat pad, with mass effect both on the suprapatellar joint recess posteriorly, and on the quadriceps tendon anteriorly. This MR appearance is analogous to Hoffa's disease described in the infrapatellar fat pad. We sought to evaluate the frequency and pattern of this finding and to provide clinical and histological correlation. PATIENTS: The suprapatellar (quadriceps) fat pad was evaluated in 770 consecutive MR examinations (on 1.5 T and 0.3 T) in 736 patients (353 females and 383 males, age range 5-86 years, mean 44.3 years). DESIGN: The MR images were retrospectively evaluated by two observers in consensus for the presence of quadriceps fat pad edema with mass effect. In 46 patients who had intravenous administration of gadolinium, the presence of enhancement was also evaluated. Clinical correlation was performed in abnormal cases; in one patient, 1-year follow-up MRI was evaluated and in one patient a percutaneous biopsy as well as 2-year clinical follow-up was performed. RESULTS: Thirty-two (4.2%) knees in 29 patients showed quadriceps fat pad edema and mass effect. In five of these patients imaging of the contralateral knee was also performed and four of these showed symmetric edema. Another five cases had gadolinium-enhanced images with prominent enhancement. Most patients had clinical symptoms of meniscal tears (n=16, 55%) or anterior knee pain (n=8, 27.6%). The remainder had nonspecific pain (n=4, 13.8%) or suspected avascular necrosis (n=1, 3.4%). In the case with 1-year follow-up MRI, improvement was seen. Biopsy in another patient revealed vasculitis with obliteration of the small vessels. Resection of the fat pad in this patient led to complete resolution of the symptoms. CONCLUSION: Suprapatellar fat pad edema may be analogous to Hoffa's disease, is rare, and may be a cause of anterior knee pain. However, this finding is not infrequent and its precise association with symptoms remains unclear.

Adipose Tissue↗

PubMed2006

Edematous Schmorl's nodes on thoracolumbar MR imaging: characteristic patterns and changes over time.

OBJECTIVE: To describe the patterns and note the evolution of edematous Schmorl's nodes. MATERIALS AND METHODS: In 47 patients (M:F=26:21, 24-86 years, average 60), 84 Schmorls nodes with T2 hyperintensity with serial MR exams were evaluated. Interval between MR exams was 2-72 months (average 17). Two observers noted size, location, margins, internal and surrounding T1/T2 signal, adjacent disc herniation or bulge, concentric ring, underlying fracture, malignancy, infection, or prior disc surgery, and serial MR changes in these characteristics over time. RESULTS: Node size averaged 7x9 mm. Most were located at L3 (29%, 24/84), L4 (19%, 16/84) and L2 (13%, 11/84), at the central (39%, 33/84) or outer (30%, 25/84) third of the endplate. 55% (39/71) had a bulging disc, 7% (5/71) had disc herniation. 10% (8/84) had evidence of associated fracture, 17% (14/84) tumor, 7% (6/84) infection. Most nodes had well-defined margins (82%, 69/84). The most common node internal signal was isointense to adjacent disc on T1/T2 (33%, 28/84); surrounding marrow was most commonly hypointense on T1 and hyperintense on T2 (54%, 38/71). A common finding was concentric rings (38%, 32/84) in the marrow surrounding the node, a finding which had 72% negative predictive value for absence of infection, tumor and fracture. On follow-up, there was no interval change in node size in 46%(39/84) of Schmorl's nodes. 26% (22/84) had increased size. Most (60%, 50/84) showed no temporal change in internal T2 signal. 21% (18/84) of nodes showed decreased internal T2 signal, 13% (11/84) showed increased T2 signal. Regarding the surrounding marrow, most (58%, 49/84) showed no temporal change in T2 signal; 21%(18/84) showed decreased T2 signal, 13% (11/84) showed increased T2 signal. In 13 Schmorl's nodes with intranodal enhancement, eight (62%) showed no interval change; among eight with enhancement in surrounding marrow, five (63%) showed no change on follow-up. CONCLUSION: Although most remain unchanged, a relatively large minority of edematous Schmorl's nodes evolve in size and signal over a relatively short time. Some evolve to form well-defined concentric rings in the surrounding marrow that appear to be analogous to degenerative changes of endplates. Concentric ring formation has a high negative predictive value for "idiopathic" Schmorl's nodes without underlying fracture, infection, or malignancy.

Adult↗

PubMed2006

3D-T1rho quantitation of patellar cartilage at 3.0T.

PURPOSE: To demonstrate the feasibility of three-dimensional (3D) T(1rho)-weighted imaging of human knee joint at 3.0T without exceeding the specific absorption rate (SAR) limits and the measurement of the baseline T(1rho) values of patellar cartilage and several muscles at the knee joint. MATERIALS AND METHODS: 3D gradient-echo sequence with a self-compensating spin-lock pulse cluster of 250 Hz power was used to acquire 3D-T(1rho)-weighted images of the knee joint of five healthy subjects. Global and regional analysis of patellar cartilage T(1rho) were performed. Furthermore, T(1rho) of several periarticular muscles were analyzed. RESULTS: The global average T(1rho) value of the patellar cartilage varied from 39 to 43 msec. The regional average T(1rho) values varied from 38 to 42 msec, and from 42 to 44 msec for medial and lateral facets, respectively. In vivo reproducibility of average T(1rho) of patellar cartilage was found to be 5% (coefficient of variation). Similarly, the global average T(1rho) values for biceps femoris, lateral gastrocnemius, medial gastrocnemius, and sartorius varied between 31-46, 29-49, 35-48, and 32-50 msec, respectively. CONCLUSION: We demonstrated the feasibility of 3D-T(1rho)-weighted imaging of the knee joint at 3.0T without exceeding SAR limits.

Adult↗

PubMed2006

The scapuloacromial angle: a 3D analysis of acromial slope and its relationship with shoulder impingement.

PURPOSE: To quantify acromial slope (the scapuloacromial [SA] angle). MATERIALS AND METHODS: We used shoulder MR studies in 64 subjects who were stratified surgically into impingement (with and without tear) and nonimpingement (shoulder instability) groups. We measure, in three dimensions, the angle between unit normal vectors to planes of best fit to the undersurface of the acromion and the medial surface of the blade of the scapula. We examine the projection of this SA angle onto the transverse, coronal, and sagittal planes to gauge some measure of rotation, lateral tilt, and anterior tilt with respect to the patient. Orientation of the acromion and scapular blade in relation to the MR scanner and therefore to the patient was also calculated. RESULTS: We found no significant differences between these two groups when examining age and side of pathology. A statistically significant difference was seen between males and females. CONCLUSION: Our study does not support the idea that a flatter acromial slope causes impingement and is an etiological basis for rotator cuff tears. We believe that acromial slope, regardless of imaging plane, is not useful in classifying patients who present with shoulder pain and should not be considered as a source of pathologic changes.

Acromion↗

PubMed2006

Rapid 3D-T1rho mapping of the knee joint at 3.0T with parallel imaging.

Three-dimensional spin-lattice relaxation time in the rotating frame (3D-T1rho) with parallel imaging at 3.0T was implemented on a whole-body clinical scanner. A 3D gradient-echo sequence with a self-compensating spin-lock pulse cluster was combined with generalized autocalibrating partially parallel acquisitions (GRAPPA) to acquire T1rho-weighted images. 3D-T1rho maps of an agarose phantom and three healthy subjects were constructed using an eight-channel phased-array coil without parallel imaging and with parallel imaging acceleration factors of 2 and 3, in order to assess the reproducibility of the method. The coefficient of variation (CV) of the median T1rho of the agarose phantom was 0.44%, which shows excellent reproducibility. The reproducibility of in vivo 3D-T1rho maps was also investigated in three healthy subjects. The CV of the median T1rho of the patellar cartilage varied between approximately 1.1% and 4.3%. Similarly, the CV varied between approximately 2.1-5.8%, approximately 1.4-8.7%, and approximately 1.5-4.1% for the biceps femoris and lateral and medial gastrocnemius muscles, respectively. The preliminary results demonstrate that 3D-T1rho maps can be constructed with good reproducibility using parallel imaging. 3D-T1rho with parallel imaging capability is an important clinical tool for reducing both the total acquisition time and RF energy deposition at 3T.

Adult↗

PubMed2006

Behavior of ordered sodium in enzymatically depleted cartilage tissue.

The onset of cartilage tissue disorders can be characterized by a loss of proteoglycans (PGs) and diagnosed by contrast-enhanced proton ((1)H) MRI techniques, as well as sodium MRI. The behavior of sodium located in anisotropic environments, is examined as a function of cartilage degeneration. PGs are proteolytically depleted from the cartilage samples, which gives rise to a decrease of the ordered sodium content. More surprisingly, however, the residual quadrupolar couplings are shown to increase with increasing depletion levels. Since the residual quadrupolar couplings are intimately related to local order and anisotropic motion, measuring their distribution in cartilage may provide insight into the structural changes that occur within the tissue upon degradation. In this study relatively mild orientational dependence of the couplings was found. Little or no free sodium was observed in the cartilage specimens under study.

Animals↗

PubMed2006

Ultra-high-field MRI of knee joint at 7.0T: preliminary experience.

RATIONALE AND OBJECTIVES: To measure signal-to-noise ratio (SNR), contrast, and relaxation times (T1 and T2) in human knee joint at 7.0T whole-body scanner. MATERIALS AND METHODS: MRI experiments were performed on a 7.0T Siemens whole-body scanner using an 18-cm diameter transmit/receive knee coil. Normalized SNR and relaxation times (T1 and T2) were computed on all volunteers (healthy, n=5) for femoral, tibial, and patellar cartilage. RESULTS: Average T1 values of femoral, tibial, and patellar cartilages were found as 1.55, 1.76, and 1.62 seconds, respectively. Average T2 values of femoral, tibial, and patellar cartilages were found as 51.3, 43.9, and 39.7 milliseconds, respectively. No statistically significant differences were observed between T1 and T2 values of different cartilage tissues (P>.08 for all comparisons). Compared with previously reported relaxation times of cartilage tissue at 3.0T, an approximately 35% increase was observed in T1 values, whereas no significant change was observed in T2. Regional analysis was also performed to investigate the change in relaxation parameters for weight-bearing vs. non-weight-bearing areas. A statistically significant difference was observed in T2 of tibial cartilage (P=.009). The rest of the comparisons yielded insignificant differences (P>.32). CONCLUSION: Our preliminary results demonstrate the feasibility of acquiring high resolution three-dimensional images of knee joint (with and without fat suppression) at 7.0T whole-body scanner.

Adult↗

PubMed2006

High-field MRI.

High-field MRI is moving rapidly from the research realm to clinical use. This modality has intrinsic advantages in signal to noise ratio, which allows images that have im-proved resolution, are obtained faster, or have less noise. Perhaps most importantly these scanners will allow functional imaging to become a reality in the musculoskeletal system. Care must be used in protocols because of the energy deposition and worsened artifacts at higher fields.

Artifacts↗

PubMed2006

Neuropathic arthropathy of the foot with and without superimposed osteomyelitis: MR imaging characteristics.

PURPOSE: To determine retrospectively the magnetic resonance (MR) findings associated with pedal neuropathic arthropathy with and without superimposed osteomyelitis and to identify any useful discriminating features. MATERIALS AND METHODS: Investigational review board approval was obtained and allowed review of records and images without informed consent. HIPAA compliance was observed. Contrast-enhanced MR images in patients with diabetic neuropathic arthropathy of the foot were examined by two reviewers in consensus. Affected joints were examined for marrow, articular, periarticular, and soft-tissue findings. Presence of superimposed osteomyelitis was documented. A subgroup that had undergone MR before infection was evaluated for comparison; chi(2) and t tests were used to evaluate the associations. RESULTS: Of 128 neuropathic joints in 63 patients (24 female, 39 male; aged 31-78 years), 43 had superimposed osteomyelitis. Effusion was common in all neuropathic joints, but thin rim enhancement was more common in noninfected joints (62% vs 21%, P < .001) and diffuse joint fluid enhancement was more common with infection (47% vs 26%, P = .052). Subluxation, bone proliferation, fragmentation, and erosion were seen in both groups, but intraarticular bodies were more common in noninfected joints (53% vs 12%, P < .001). In the periarticular soft tissues, edema, enhancement, and ulceration were common in both groups. Fluid collections in the soft tissues were more commonly associated with infected joints (95% vs 48%, P < .001) and, when present next to an infected joint, were larger than those next to noninfected neuropathic joints (2.6 cm(2) [range, 0.3-8.6 cm(2)] vs 1.6 cm(2) [range, 1.0-2.4 cm(2)]). Soft-tissue fat replacement (68% vs 36%, P = .002) and sinus tracts (84% vs 0%, P < .001) were also more common with infection. In the marrow, periarticular signal intensity abnormality was common in both groups, but the extent was greater with infection. Subchondral cysts were seen almost exclusively in noninfected joints (76% vs 2%, P < .001). Similar results were obtained in the subgroup of 21 joints (15 patients) with both pre- and postinfection MR images. CONCLUSION: Sinus tract, replacement of soft-tissue fat, fluid collection, and extensive marrow abnormality are MR imaging features indicating superimposed infection. Thin rim enhancement of effusion, presence of subchondral cysts, or intraarticular bodies indicate absence of infection.

Adult↗

PubMed2006

MR imaging features of radial tunnel syndrome: initial experience.

PURPOSE: To retrospectively assess magnetic resonance (MR) imaging features of radial tunnel syndrome. MATERIALS AND METHODS: Institutional review board approval was obtained, and informed consent was waived for the retrospective HIPAA-compliant study. MR images of 10 asymptomatic volunteers (six men, four women; mean age, 30 years) and 25 patients (11 men, 14 women; mean age, 49 years) clinically suspected of having radial tunnel syndrome were reviewed for morphologic and signal intensity alterations of the posterior interosseous nerve and adjacent soft-tissue structures. MR images of the asymptomatic volunteers were reviewed to establish the normal appearance of the radial tunnel. MR images of the symptomatic patients were evaluated for the following: signal intensity alteration and morphologic alteration of the posterior interosseous nerve; the presence of mass effect on the posterior interosseous nerve such as the presence of bursae, a thickened leading edge of the extensor carpi radialis brevis, or prominent radial recurrent vessels; signal intensity alteration within the depicted forearm musculature such as edema or atrophy; and signal intensity changes at the origin of the common extensor and common flexor tendons, which would suggest a diagnosis of epicondylitis. RESULTS: All images of volunteers demonstrated normal morphology and signal intensity within the posterior interosseous nerve and adjacent soft tissues. Two volunteers had borderline thickening of the leading edge of the extensor carpi radialis brevis. Thirteen patients (52%) had denervation edema or atrophy within muscles (supinator and extensors) innervated by the posterior interosseous nerve. One patient had isolated pronator teres edema. Seven (28%) patients had the following mass effects along the posterior interosseous nerve: thickened leading edge of the extensor carpi radialis brevis (n = 4), prominent radial recurrent vessels (n = 1), schwannoma (n = 1), or bicipitoradial bursa (n = 1). The rest of the patients had either normal MR imaging findings (n = 4) or lateral epicondylitis (n = 2). CONCLUSION: Muscle denervation edema or atrophy along the distribution of the posterior interosseous nerve is the most common MR finding in radial tunnel syndrome.

Adult↗

PubMed2005

Evaluation of posterior tibial pathology: comparison of sonography and MR imaging.

OBJECTIVE: To compare the results of sonographic (US) and magnetic resonance (MR) imaging in detecting pathology of the posterior tibial tendon (PTT) in patients with PTT dysfunction. DESIGN: Twenty-two ankles that were clinically suspected by the orthopedic surgeon to have PTT dysfunction were evaluated with US (10 MHz linear-array transducer) and 1.5 T MR examinations within the same day. The US and MR studies were conducted and interpreted by two sonologists and two musculoskeletal radiologists who were masked to the results of the other study. Four patients had bilateral studies. Classic clinical findings were utilized as a standard reference in staging PTT dysfunction. PATIENTS: Eighteen women (mean age 61 years, age range 39-86 years). RESULTS: Based on a commonly accepted staging system for PTT dysfunction, 6 ankles were classified as stage I, 11 ankles as stage II, and 5 ankles as stage III. All stage I ankles were interpreted as having an intact PTT by both MR imaging and US. In the stage II and III tendons, MR imaging demonstrated PTT tears in 12 of 22 examinations, including 11 partial tears and 1 complete tear. US demonstrated PTT tears in 8 of 22 examinations, including 8 partial tears and no complete tears. The findings of US and MR imaging were consistent in 17 of 22 cases (77%). The five inconsistencies were as follows: in 4 cases, US reported tendinosis when MR imaging interpreted partial tears (no change in management); in one case, US diagnosed a partial tear when MR reported a complete tear of the PTT (no change in management because the clinical findings were more consistent with a partial tear). CONCLUSIONS: In this study, US and MR imaging of the PTT were concordant in the majority of cases. US was slightly less sensitive than MR imaging for PTT pathology, but these discrepancies did not affect clinical management.

Adult↗

PubMed2005

Reactive endplate marrow changes: a systematic morphologic and epidemiologic evaluation.

PURPOSE: To evaluate the morphology and location of vertebral endplate changes, and to analyze their association with age, gender, and body mass index (BMI). DESIGN AND PATIENTS: At 1.5 T (T1-weighted, T2-weighted/STIR) 100 lumbar spines were evaluated separately by three observers. The readers classified the endplate bone marrow abnormalities on sagittal MR images according to the definitions of Modic et al. Findings were localized by disc segment; whether in the upper and/or lower endplate; and within each endplate divided into 15 segments. Disc space narrowing, as well as disc desiccation, was also noted at each vertebral level. In addition, endplate changes were correlated with age, gender, and BMI (weight(kg)/height(m)2). RESULTS: A total of 15,000 data points were studied and 422 total changes recorded. A total of 99 vertebral levels were affected in 58 patients. Of these, 171 were of type I, 242 were of type II, and 9 were of type III. L4-L5 and L5-S1 vertebral levels were most commonly involved, having (142, 4.73%) and (116, 3.87%) changes respectively (P<0.0001). The upper and lower aspects of the endplate were affected similarly. Changes most frequently occurred at the anterior aspect of the endplate (P<0.0001). Endplate marrow changes were associated with increasing age (P<0.0001) and, surprisingly, male gender (P<0.0001). Endplate changes were not associated with BMI. CONCLUSION: The fatty pattern was most common, with the sclerotic pattern being rare. Endplate marrow changes most often occurred at the anterior aspect of the endplate, particularly at L4--L5 and L5--S1 levels. Modic changes occur more frequently with aging, evidence of their degenerative etiology. They were, however, not related to body habitus, but to weight and male gender.

Adolescent↗

PubMed2005

Optimization of indirect arthrography of the knee by application of external heat: initial experience.

PURPOSE: To examine the potential utility of applying heat to increase the uptake of intravenous gadolinium (Gd) contrast into the knee joint in order to optimize MR arthrography. MATERIALS AND METHODS: At 1.5T, 16 knees in eight patients without prior surgery, injury, or pain were examined before and 30 minutes after intravenous administration of Gd contrast (0.1 mM/kg). Between scans a heating pad was applied to the anterior aspect of eight randomly selected knees (the contralateral knee served as the control). Initial and postcontrast imaging consisted of identical axial T1-weighted sequences (TR/TE = 500/14 msec) without fat suppression. On the initial and postcontrast images, regions of interest (ROIs) were placed at identical locations in the suprapatellar pouch and the intercondylar notch by a reader blinded to the treated side. The values at these two locations were averaged and the change in joint signal intensity was calculated. The differences between the heated and unheated knees were also calculated. RESULTS: Seven of the eight knees treated with heat had increased joint enhancement compared to the contralateral control, with percentage changes in joint signal intensity (heated knee vs. control) of +38%, +80%, +121%, +145%, +150%, +164%, and +177%. Overall there was a doubling of signal intensity (125%) on the heated side compared to the contralateral control (with significance at P = 0.039). One patient was excluded because of a prior knee injury. CONCLUSION: The application of external heat increases uptake of intravenously administered Gd contrast into the knee joint, and may help to optimize indirect MR arthrography at a relatively low cost.

Adult↗

PubMed2005

MR imaging of the diabetic foot: diagnostic challenges.

Pedal complications of diabetes have long presented a challenge for the clinician and radiologist predominately related to the difficulty in distinguishing infection from neuroarthropathy. The spectrum of diabetic foot infections is broad, ranging from callous and ulcer formation, to septic arthritis, abscess formation, and osteomyelitis. This article summarizes the MR imaging findings in the diabetic foot and the optimal pulse sequences. Focus is placed on aids in differentiating diabetic infection from other entities and increasing the specificity of diagnosing diabetic foot complications.

Abscess↗