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Biomedical subjects

Mark E Schweitzer

Publications and source records attributed to Mark E Schweitzer.

At least 19 recordsLinked to original sources
PubMed2004

Accuracy of plain films, and the effect of experience, in the assessment of ankle effusions.

OBJECTIVE: To investigate the accuracy of plain radiographs, and the effect of observer experience, in the assessment of ankle effusions compared with an MRI gold standard. DESIGN AND PATIENTS: Anteroposterior (AP) and lateral radiographs of the ankle of 39 patients were evaluated by four observers, ranging from first-year radiology resident to an attending musculoskeletal radiologist. Observers independently graded the lateral films from 0 to 5 at one sitting, and the AP films at a second sitting. All patients had an MRI scan performed within 48 h of the ankle radiographs, on which distention of the anterior recess was used as the gold standard for an effusion. RESULTS: Lateral radiographs had variable sensitivity (range 17-63%), but specificity (81-94%) was usually high. AP radiographs similarly had variable sensitivity (15-55%), but their specificity (63-75%) was surprisingly good. Overall, sensitivity and specificity were inversely proportional and more related to individual variability than experience (observer 1, 53% and 81%; observer 2, 17% and 94%; observer 3, 63% and 88%; observer 4, 21% and 94%); however, individual sensitivity and specificity were consistent between AP and lateral radiographs (observer 1, 53% and 81%, 50% and 65%; observer 2, 17% and 94%, 15% and 75%), observer 3, 63% and 88%, 55% and 63%; observer 4, 21% and 94%, 25% and 70%). Positive predictive value was reasonably good for lateral radiographs (range 75-86%); however, it was fairly low for AP radiographs (38-61%). Negative predictive value was low for both lateral (50-67%) and AP (47-58%) radiographs. Accuracy was low for both AP (45-59%) and lateral (53-74%) radiographs. As expected, individual accuracy was consistently higher for lateral radiographs than for AP radiographs (observer 1, 65% and 58%; observer 2, 53% and 45%; observer 3, 74% and 59%; observer 4, 54% and 48%). CONCLUSIONS: For the diagnosis of ankle effusions the overall accuracy of radiographs was surprisingly low. Quite surprisingly, the diagnosis of effusions on AP radiographs was not much poorer than on lateral films. Results, however, varied little with experience and training.

Adult↗
PubMed2004

MRI criteria for patella alta and baja.

OBJECTIVE: To determine the range of the patellar tendon length to patellar length ratio on magnetic resonance imaging (MRI) of the knee in order to aid in the establishment of MRI criteria for patella alta and baja. PATIENTS: Two hundred and forty-five patients ages 6-85 (mean 44) years who went through 262 consecutive 1.5 MRI studies of the knee performed during November 2000 through February 2001 were evaluated, regardless of their clinical symptoms. DESIGN: Patellar length (PL) and patellar tendon length (TL) were measured by a single musculoskeletal radiologist on sagittal images by a line connecting the superior and inferior patellar poles and the shortest length of the inner margin of the tendon respectively. TL/PL ratio was subsequently calculated. The distribution of ratios was evaluated; the extreme 2.5% at each end of the distribution was defined as patella alta and baja. RESULTS: The TL/PL ratio ranged between 0.56 and 1.71 (mean 1.05). After plotting the ratios, we noted an asymmetric curve skewed to the left. Based upon calculation of the extreme 2.5% of the ratio at each end of the plot, we determined that the MRI definition of patella alta and baja is a ratio of TL/PL of more than 1.50 and less than 0.74 respectively. We found that females had significantly higher TL/PL ratio than males (1.0878 and 1.0032 respectively). Ratios defined for patella alta and baja were 1.52 and 0.79 respectively in females and 1.32 and 0.74 respectively in males ( p<0.0001). CONCLUSION: Patella alta and baja are determined as TL/PL of more than 1.50 and less than 0.74 respectively, somewhat different than traditionally quoted radiographic and previously described MRI criteria.

Adolescent↗
PubMed2004

Thoracic spine disc-related abnormalities: longitudinal MR imaging assessment.

OBJECTIVE: To describe and characterize the temporal changes in disc-related disorders of the thoracic spine using MR imaging. DESIGN AND PATIENTS: A retrospective longitudinal cohort study was carried out of 40 patients with two sequential thoracic spine MR images at variable intervals. The images were assessed for baseline presence of, new incidence of and changes in disc herniation, degenerative disc disease, endplate marrow signal alteration and Schmorl nodes. RESULTS: The range of follow-up was 4-149 weeks. Baseline presence was: disc herniation, 10% (49/480); degenerative disc disease, 14% (66/480); endplate marrow signal alteration, 2.3% (11/480); Schmorl nodes 9.6% (46/480). Most pre-existing lesions tended to remain unchanged. Herniations showed the most change, tending to improve in 27%. New incidence was: disc herniation, 1.5% (7/480), degenerative disc disease, 2% (10/480); endplate marrow signal alteration, 1.6% (8/480); Schmorl nodes, 2.1% (10/480). Disc degeneration was first visible at an 11-week interval and once established almost never changed over many weeks to months. Endplate signal alterations (Modic changes) were uncommon. Schmorl nodes show no change from baseline for up to 2 1/2 years. All findings predominated in the lower intervertebral levels from T6 to T10. CONCLUSION: The most prevalent thoracic spine disc-related findings are degeneration and herniation. Disc herniations predominate in the lower segments and are a dynamic phenomenon. Disc degeneration can be rapidly evolving but tends to remain unchanged after occurrence. Endplate marrow signal changes were an uncommon manifestation of thoracic disc disease. Schmorl nodes showed the least change over time.

Female↗
PubMed2004

Trends in utilization: has extremity MR imaging replaced diagnostic arthroscopy?

OBJECTIVE: To examine the relative change in utilization of magnetic resonance (MR) imaging of the extremities versus diagnostic and therapeutic arthroscopy. DESIGN AND PATIENTS: Using the 1993, 1996, and 1999 nationwide Medicare Part B databases, utilization rates (per 100000) were determined for upper and lower extremity MR imaging, diagnostic arthroscopy and therapeutic arthroscopy using CPT-4 codes. Utilization of extremity MR imaging was compared with that of diagnostic and therapeutic arthroscopy in 10 geographic regions of the United States and tracked over time. RESULTS: Combined lower and upper extremity MR imaging utilization per 100000 increased from 393 to 1056 in 1999 (+168.7%). Utilization of diagnostic arthroscopy of the extremities decreased from 18 in 1993 to 8 in 1999 (-55.6%); therapeutic arthroscopy rates increased from 461 in 1993 to 636 in 1999 (+40.0%). Specifically, from 1993 to 1999, utilization of lower extremity MR imaging increased from 270 to 661 (+144.8%). Utilization of diagnostic arthroscopy of the knee over the same time period decreased from 11 to 5 (-54.5%); therapeutic arthroscopy increased from 394 to 501 (+27.2%). Similarly, utilization rates for upper extremity MR imaging increased from 123 to 395 (+221.1%). Utilization of diagnostic arthroscopy of the shoulder over the same time period decreased from 7 to 2 (-71.4%); therapeutic arthroscopy increased from 44 to 104 (+136.4%). No specific geographic trends were ascertained. CONCLUSION: The utilization of MR imaging of the extremities has markedly increased from 1993 to 1999. During the same time period the utilization of diagnostic arthroscopy has decreased and that of therapeutic arthroscopy has increased. These findings support the hypothesis that there is increased reliance of clinical practitioners on the diagnostic information provided by MR imaging in preoperative clinical decision-making.

Aged↗
PubMed2004

MR imaging of the diabetic foot.

Diabetes is a common disease with potentially devastating complications affecting the foot and ankle. Ischemia and infarction, neuropathic osteoarthropathy, callus, ulceration, and infection result from the underlying neurologic and vascular disease. The MR imaging appearance of these complications is discussed. Recognition of these MR imaging patterns is important for formulation of an appropriate treatment plan.

Amputation, Surgical↗
PubMed2004

MRI findings of septic arthritis and associated osteomyelitis in adults.

OBJECTIVE: The purpose of this study was to describe the soft-tissue, synovial, and osseous MRI findings of septic arthritis. MATERIALS AND METHODS: At 1.5 T (T1-weighted, T2-weighted or STIR, and contrast-enhanced images), 50 consecutive cases of septic arthritis were evaluated by two observers for synovial enhancement, perisynovial edema, joint effusion, fluid outpouching, fluid enhancement, and synovial thickening. The marrow was assessed for abnormal signal on T1- and T2-weighted images or after contrast enhancement. We noted whether the marrow signal was diffuse or abnormal in bare areas. MRI findings were compared with microbiologic, clinical, and surgical data and diagnoses. RESULTS: The frequency of MRI findings in septic joints was as follows: synovial enhancement (98%), perisynovial edema (84%), joint effusions (70%), fluid outpouching (53%), fluid enhancement (30%), and synovial thickening (22%). The marrow showed bare area changes (86%), abnormal T2 signal (84%), abnormal gadolinium enhancement (81%), and abnormal T1 signal (66%). Associated osteomyelitis more often showed T1 signal abnormalities and was diffuse. CONCLUSION: Synovial enhancement, perisynovial edema, and joint effusion had the highest correlation with the clinical diagnosis of a septic joint. However, almost a third of patients with septic arthritis lacked an effusion. Abnormal marrow signal-particularly if it was diffuse and seen on T1-weighted images-had the highest association with concomitant osteomyelitis.

Adult↗
PubMed2004

MRI findings associated with distal tibiofibular syndesmosis injury.

OBJECTIVE: Our objective was to describe the MRI findings associated with acute and chronic distal tibiofibular syndesmosis injury. MATERIALS AND METHODS: Ninety-four 1.5-T MRIs of ankles of 90 individuals with histories of severe sprain were assessed by two musculoskeletal radiologists for syndesmosis injury (acute, edema of the syndesmosis; chronic, disruption or thickening of the syndesmosis without edema). We examined associated MRI findings, including anterior talofibular ligament injury (scar, chronic injury; edema, acute injury), bone bruise, osteochondral lesion, tibiofibular joint congruity, tibiofibular recess height, and osteoarthritis. The Fisher's exact test and analysis of variance test were used to evaluate the significance of the associations. RESULTS: In 94 ankles, syndesmosis injury was seen in 63% (n = 59; 23 acute; 36 chronic). Anterior talofibular ligament injury (acute or chronic) was seen on MRIs in 74% (n = 70; 49 with syndesmosis injury; 21 without; p = 0.03). Bone bruises were present in 24% (n = 23; 18/23 acute; 4/36 chronic; 4/35 no injury; p < 0.0001). Of these, talar dome osteochondral lesions were present in 28% (n = 26; 11/23 acute; 14/36 chronic; 1/35 no injury; p = 0.0001; 13 medial; 13 lateral). The tibiofibular joint was incongruent in 33% (n = 31; 6/23 acute; 21/36 chronic; 4/35 no injury; p < 0.0001). The tibiofibular recess (mean +/- SD) was 1.2 +/- 0.92 cm in acute cases, 1.4 +/- 0.57 cm in chronic cases, and 0.54 +/- 0.68 cm in cases with no syndesmosis injury (p < 0.0001). Osteoarthritis was present in 10% (n = 9; 1/23 acute; 7/36 chronic; 1/35 no injury; p = 0.06). CONCLUSION: Injury to the distal tibiofibular syndesmosis has a significant association with a number of secondary findings on MRI, including anterior talofibular ligament injury, bone bruises, osteochondral lesions, tibiofibular joint congruity, and height of the tibiofibular recess.

Acute Disease↗
PubMed2004

MRI in the diagnosis of cartilage injury in the wrist.

OBJECTIVE: Our purpose was to evaluate the accuracy of MRI in identifying articular cartilage abnormalities in the distal radius, scaphoid, lunate, and triquetrum of patients with wrist pain. MATERIALS AND METHODS: Eighty-six MRI examinations of the wrist in 85 patients (41 indirect MR arthrograms and 45 unenhanced [nonarthrographic] MR images) were evaluated. The study population consisted of 47 male (54.7%) and 38 female (45.3%) patients with an average age of 37.5 years (range, 7-62 years). Three experienced musculoskeletal radiologists who were unaware of surgical findings retrospectively evaluated the MRI examinations for cartilage abnormalities in the distal radius, scaphoid, lunate, and triquetrum. All patients underwent arthroscopy of the radiocarpal joint with inspection of the articular surfaces of the distal radius, scaphoid, lunate, and triquetrum. The articular cartilage was evaluated on the basis of the 5-point scale of the Outerbridge classification system. RESULTS: When at least two of the three radiologists had concordant interpretations, sensitivity for abnormalities in the distal radius was 27%; the scaphoid, 31%; the lunate, 41%; and the triquetrum, 18%. Specificity for the distal radius was 91%; the scaphoid, 90%; the lunate, 75%; and the triquetrum, 93%. Weighted kappa values among the three observers showed only fair agreement (0.279-0.360). High-grade more extensive cartilage lesions were no more accurately identified than low-grade lesions. Indirect MR arthrograms were not statistically more sensitive, specific, or accurate than unenhanced studies. No bone was more frequently or less frequently graded correctly or incorrectly with statistical significance. The variables of sex, age, and the presence of multiple bones with lesions did not affect accuracy. CONCLUSION: Our findings suggest that MRI of the wrist with the techniques described is not adequately sensitive or accurate for diagnosing cartilage defects in the distal radius, scaphoid, lunate, or triquetrum.

Adolescent↗
PubMed2003

MR imaging of anterior cruciate ligament tears: is there a gender gap?

OBJECTIVE: Clinically, females receive anterior cruciate ligament (ACL) tears more commonly than males. We explored whether gender differences exist in MR imaging patterns of ACL tears. DESIGN AND PATIENTS: At 1.5 T, two observers evaluated MR examinations of 84 consecutive age-matched patients (42 males, 42 females, aged 16-39) with ACL tears, for mechanism of injury, extent and type of tear, the presence of secondary signs and associated osseous, meniscal and ligamentous injuries. RESULTS: The most common mechanism of injury for both females and males was the pivot shift mechanism (67 and 60%, respectively). Females were more commonly imaged in the acute stage of tear than males (98 and 67%, respectively, p=0.001) and more commonly possessed the typical posterolateral tibial bone contusion pattern (88 and 62%, respectively, p=0.0131). Males exhibited a deeper femoral notch sign (2.7 and 2.0 mm, p=0.007) and medial meniscal, lateral collateral ligament and posterior cruciate ligament injuries more commonly than females (48 and 24%, p=0.009, 30 and 7%, p=0.035, 17 and 0%, p=0.035). There was no significant difference between genders for the presence of other secondary signs and contusion patterns, associated lateral meniscal tears, presence of O'Donoghue's triad or associated medial collateral ligament injuries. CONCLUSION: Gender differences in MR imaging patterns of ACL tears exist: females are more commonly imaged in the acute stage and more commonly possess posterolateral tibial bone contusions; males have a more severe presentation than females, associated with more severe lateral femoral condyle and soft tissue injuries.

Acute Disease↗
PubMed2003

MR imaging findings in spinal infections: rules or myths?

PURPOSE: To systematically evaluate magnetic resonance (MR) imaging findings described as being indicative of spinal infection in patients with proven spinal infection. MATERIALS AND METHODS: Contrast material-enhanced spinal MR images obtained in 46 consecutive patients (22 women, 24 men; mean age, 58.2 years) with culture or histologic examination results positive for spinal infection were systematically evaluated by two observers. Tuberculous and postoperative infections were excluded. Disk signal intensity and disk height, presence of the nuclear cleft, vertebral signal intensity alterations, endplate erosions on T1-weighted MR images, and presence of paraspinal or epidural inflammation were evaluated. Patient charts and surgical reports were reviewed. RESULTS: In the 44 patients with disk infection, MR imaging criteria with good to excellent sensitivity included presence of paraspinal or epidural inflammation (n = 43, 97.7% sensitivity), disk enhancement (n = 42, 95.4% sensitivity), hyperintensity or fluid-equivalent disk signal intensity on T2-weighted MR images (n = 41, 93.2% sensitivity), and erosion or destruction of at least one vertebral endplate (n = 37, 84.1% sensitivity). Effacement of the nuclear cleft was only applicable in 18 patients (n = 15, 83.3% sensitivity). Criteria with low sensitivity included decreased height of the intervertebral space (n = 23, 52.3% sensitivity) and disk hypointensity on T1-weighted MR images (n = 13, 29.5% sensitivity). Involvement of several spinal levels occurred in seven (16%) patients. Other spinal infections included isolated vertebral osteomyelitis (n = 1) and primary epidural abscess (n = 1). CONCLUSION: Most MR imaging criteria commonly used to diagnose disk infections offer good to excellent sensitivity. In atypical manifestations of proven spinal infections, however, some of the classically described MR imaging criteria may not be observed.

Adult↗
PubMed2003

Imaging sports injuries of the foot and ankle.

The complexity of foot and ankle anatomy and function is unique in the musculoskeletal system. Understanding the complex anatomy alone is a daunting task, not to mention transferring that understanding to the two-dimensional planes encountered on imaging studies. When evaluating sports injuries in the foot and ankle, the interpreting radiologist must take into account the type of activity, vector of stress, and inherent characteristics of the involved structures. A strong working relationship with the health care providers managing patient care, ideally orthopedists, is essential. But in this age of decreasing specialization and increasing availability of imaging resources, the interpreting radiologist must use all available tools for clinical investigation. When interpreting an ankle or foot MR imaging, one finding should trigger a search for the next finding along a logical pathway of injury evolution. Bone marrow edema patterns are guides to tendon and ligament failure. And a clinical syndrome without correlative imaging diagnosis should call attention to potential alternative diagnoses. As the number of MR imaging studies performed continues to increase and MR technology continues to improve, we expect further advancements in MR evaluation of foot and ankle injury. We hope to continue to work closely with our referring orthopedists in this arena to improve our diagnostic skills and our understanding of foot and ankle injury.

Ankle Injuries↗
PubMed2003

Indirect magnetic resonance arthrography: applications in sports imaging.

Indirect magnetic resonance (MR) arthrography is an imaging tool with several advantages over both direct MR arthrography and unenhanced musculoskeletal magnetic resonance imaging. It is based upon the idea that paramagnetic contrast agents injected intravenously into the plasma compartment ultimately will perfuse the articular space. Advantages of indirect MR arthrography include enhancement of both intra-articular and extra-articular pathology without the need for an invasive, fluoroscopically guided arthrogram, as well as high sensitivity for reinjury in postoperative patients. Some potential disadvantages of this technique are enhancement of normal vascular tissues and difficulty in making a diagnosis dependent upon joint space distension in the absence of an effusion. Important technical issues when performing indirect arthrography include choosing an appropriate delay between contrast injection and imaging, as well as the potential use of patient exercise to improve image quality. In sports medicine, indirect MR arthrography is most useful in and about small joints such as the wrist and ankle; in articulations with potential internal derangements, as well as bony or osteochondral injuries; and in injured joints that have been altered surgically.

Arthrography↗
PubMed2003

Internal derangement of the wrist: indirect MR arthrography versus unenhanced MR imaging.

PURPOSE: To compare indirect magnetic resonance (MR) arthrography with unenhanced MR imaging of the wrist for evaluation of the central disk of the triangular fibrocartilage complex (TFCC) and the scapholunate and lunotriquetral interosseous ligaments. MATERIALS AND METHODS: Eighty-six wrists were evaluated at MR imaging (41 indirect MR arthrography and 45 unenhanced MR imaging examinations). Three musculoskeletal radiologists independently evaluated the central disk of the TFCC and scapholunate and lunotriquetral ligaments and compared the results with those of wrist arthroscopy. Sensitivity and specificity were calculated for each of the readers, and the means were obtained. Sensitivities and specificities were compared with the Student t test. RESULTS: Thirty-three tears of the central disk of the TFCC and 13 scapholunate and 18 lunotriquetral ligament tears were identified at arthroscopy. Sensitivities and specificities were 54%-73% and 83%-91%, respectively, in the evaluation of the central disk of the TFCC, with no significant difference between indirect MR arthrography (P =.666) and unenhanced MR imaging (P =.559). Sensitivities and specificities in the evaluation of the scapholunate ligament were 38%-69% and 75%-99%, respectively, with a significant improvement in sensitivity at indirect MR arthrography (P =.017) and no significant difference in specificity (P =.876). Sensitivities in the evaluation of the lunotriquetral ligament were poor, 0%-22%, though the specificities were 88%-99%, with no significant difference between indirect MR arthrography and unenhanced MR imaging (P =.592 and P =.354, respectively, for sensitivity and specificity. CONCLUSION: Indirect MR arthrography significantly improves sensitivity in the evaluation of the scapholunate ligament when compared with unenhanced MR imaging of the wrist but does not significantly improve the ability to evaluate the central disk of the TFCC or the lunotriquetral ligament.

Adult↗
PubMed2003

MR imaging of the lumbar spine: relation of posterior soft-tissue edema-like signal and body weight.

OBJECTIVE: Our purpose was to determine the association between posterior lumbar spine subcutaneous edema, fluid collections, and body weight on lumbar spine MR imaging. MATERIALS AND METHODS: MR images of the lumbar spine obtained at 1.5 T of 307 consecutive outpatients (191 female, 116 male) were reviewed on the basis of MR imaging signal characteristics for the presence, degree, size, and location of presumed subcutaneous posterior soft-tissue edema and fluid collections. The patients were divided into three weight groups (<70, 70-85, or > 85 kg) and two age groups (<50 or >/=50 years old). Edema was graded on a scale of 0-5 according to its length relative to the vertebral bodies. When present, the fluid collection volumes were calculated. The vertical epicenter of the signal abnormality was noted by vertebral body level. RESULTS: Lumbar soft-tissue edema was seen in 121 patients (39%), and discrete fluid collections were seen in 53 patients (17%). Both degree of edema and volume of fluid collection were associated with increasing weight (p < 0.001 and p = 0.002, respectively) and increasing age (p < 0.001 and p = 0.01, respectively). The degree of edema in females was significantly greater than in males (p = 0.003). However, the sex of the patient did not correlate with frequency of fluid collections (p = 0.12) or volume of collections (p = 0.08). The mean epicenters of edema in females and males were at similar levels (L3.4 and L3.9, respectively, p = 0.54). CONCLUSION: The severity of posterior lumbar subcutaneous edema and the volume of fluid collections on MR imaging are associated with increased weight.

Adolescent↗
PubMed2003

MRI features of chronic injuries of the superior peroneal retinaculum.

OBJECTIVE: The aims of this study were to assess, grade, and surgically correlate previously unreported MRI features of superior peroneal retinacular injuries in nine surgically proven cases and to record all soft-tissue and bony abnormalities associated with these injuries. CONCLUSION: MRI was found to be a useful tool for detecting and grading superior peroneal retinacular injuries and providing information, important for presurgical planning, regarding common concomitant soft-tissue and osseous abnormalities of the lateral collateral ligaments, peroneal tendons, and fibular groove. Superior peroneal retinacular injuries are frequently associated with MRI evidence of peroneal tendon dislocations and tears. Conversely, routine MRI studies may not depict dislocated peroneal tendon injuries, despite clinical history to that effect.

Adult↗
PubMed2002

Effects of iodinated contrast and field strength on gadolinium enhancement: implications for direct MR arthrography.

PURPOSE: To optimize direct magnetic resonance (MR) arthrography by determining the effect of dilution of gadolinium in iodinated contrast, saline, or albumin on T1-weighted, T2-weighted, and gradient-recalled echo (GRE) images, and the effect of scanner field strength. MATERIALS AND METHODS: Gadopentetate dimeglumine was diluted into normal saline, albumin, or iodinated contrast (0.625 mmol/liter to 40 mmol/liter). Samples were scanned at 1.5T and 0.2T. Signal intensity was measured using T1-weighted spin-echo (SE), T2-weighted SE, and two- and three-dimensional GRE (20 degrees-75 degrees flip angle) sequences. Graphical analysis of signal intensity vs. gadolinium concentration was performed. RESULTS: Albumin had no effect on gadolinium contrast. Dilution of gadolinium in iodinated contrast decreased signal intensity on all sequences compared to samples of identical concentration diluted in saline at both 1.5T and 0.2T: with a 2 mmol/liter gadolinium solution at 1.5T, signal was decreased by 26.1% on T1-weighted images, 31.7% on GRE20 images, and 28.9% on GRE45 images, and the T2 value decreased by 71.1%; at 0.2T, signal was decreased by 23.5% on T1-weighted images. On all sequences, the peak signal shifted to the left (lower gadolinium concentration) when diluted in iodinated contrast. Peak signal was also seen at different gadolinium concentrations on different sequences and field strength: at 1.5T, peak in saline/iodine was 2.5/0.625 mmol/liter on T1-weighted images, and 2.5/1.25 mmol/liter on GRE20 and GRE45 sequences. At 0.2T, peak in saline/iodine was 0.625-2.5/1.25 mmol/liter on T1-weighted images, 0.625-2.5/1.25 on GRE45 images, 2.5-10.0/1.25-5.0 mmol/liter on GRE65 images, and 1.25-5.0/0.625-1.25 mmol/liter on GRE75 images. CONCLUSION: Dilution of gadolinium in iodinated contrast results in decreased signal on T1-weighted, T2-weighted, and GRE images compared to dilution in saline or albuminfor both 1.5-T and 0.2-T scanners; if gadolinium is diluted in iodinated contrast for MR arthrography, a lower concentration should be used because the peak is shifted to the left. The use of iodinated contrast should be minimized, as it may diminish enhancement and lower the sensitivity and specificity of MR arthrography. Optimal gadolinium concentration for MR arthrography is dependent on scanner field strength and a broader range of gadolinium concentration can be used to provide maximal signal at low field strength.

Arthrography↗
PubMed2002

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.

Athletic Injuries↗