Ustun Aydingoz

Normative measurements of orbital structures using MRI.

PURPOSE The purpose of this work was to establish criteria for the diameters of normal extraocular muscles and superior ophthalmic vein and width of the optic nerve-sheath complex, to determine normal globe position as seen on MRI, and to investigate the effects of age and sex on these structures. METHOD Diameters of the extraocular muscles and superior ophthalmic vein, width of the optic nerve-sheath complex, and distance from the interzygomatic line to the posterior margin of the globe were calculated for 200 normal orbits of 100 patients on T1-weighted MR scans. RESULTS Normal ranges for diameters of the extraocular muscles were as follows (mean +/- 2 SD): medial rectus, 3.2-4.9 mm; lateral rectus, 2.6-4.8 mm; inferior rectus, 3.7-6.0 mm; superior group, 3.1-5.6 mm; superior oblique, 2.4-4.1 mm. The normal position of the posterior pole of the globe was 8.9 mm behind the interzygomatic line (range 5.0-12.7 mm). The mean diameters of the extraocular muscles in male patients were significantly larger than those in female patients (p < 0.001). CONCLUSION These data may be of value in quantitatively evaluating MRI of the orbit.

Comparison of MR signal intensities of cerebral perivascular (Virchow-Robin) and subarachnoid spaces

Purpose The purpose of this work was to compare quantitatively the T2-weighted MR signal intensity values of the perivascular (Virchow–Robin) spaces and the cerebrospinal fluid (CSF). Method Coronal 3D T2-weighted turbo spin echo MR images of the brain were evaluated in 44 subjects without any significant cerebral pathology. MR signal intensity values of the perivascular spaces around the anterior commissure and the CSF in the ventricles and the subarachnoid space were measured. Results A statistically significant difference between the mean MR signal intensity values of the perivascular spaces and the CSF both in the ventricles and in the subarachnoid space was found. The intensity values in the ventricles and in the subarachnoid space were not statistically significantly different. Conclusion The perivascular spaces have a different MR signal intensity than the CSF-containing structures within and around the brain. This finding is in keeping with the statement that the perivascular spaces represent entrapments of interstitial fluid and are not the invagination of CSF-filled subarachnoid sheaths.

MR imaging of the acetabular labrum: a comparative study of both hips in 180 asymptomatic volunteers

Abstract The aim of this study was to determine the MR imaging characteristics of normal acetabular labra on both hips. Three hundred sixty acetabular labra on both hips of 180 asymptomatic volunteers were examined on a 0.5-T MR unit utilizing a superficial coil.

The effect of pedicle screw placement with or without application of compression across the neurocentral cartilage on the morphology of the spinal canal and pedicle in immature pigs.

Study Design. Experimental study. Objectives. To investigate the effects of pedicle screw insertion on spinal canal and pedicle morphology in immature pigs, and, if transpedicular fixation has an effect, to document whether this occurs because of the inhabitance of the screw inside the growth plate (neurocentral cartilage [NCC]) or because of compression applied across the NCC. Summary of Background Data. Transpedicular fixation has been less commonly applied to the pediatric population, especially because of the risk of damage to the NCC. Methods. Twelve newborn pigs (4−6 weeks of age) were operated on. Left sided pedicles from L1–L5 were studied, while right sides served as controls. Pigs were randomly assigned into 3 groups: (1) pedicles were probed only; (2) screws were inserted; and (3) after screw insertion, a washer and a nut were engaged at the pedicle entry point so that gradual compression across the NCC was achieved. After 4 months, spiral computerized tomography was used to measure the pedicle lengths and size of the halves of the spinal canal. Results. In group 1, the operated hemi-canal area was not statistically different from the nonoperated side (P = 0.159). Pedicle screw insertion either with (P = 0.007) or without (P = 0.005) compression resulted in smaller hemi-canal area and shorter pedicles at the operated side, respectively (P = 0.008, P = 0.021). Approximately 4% to 9% shortening of the pedicle lengths and 20% to 26% narrowing of the hemi-canal areas on the instrumented side occurred with transpedicular instrumentation (groups 2, 3). Conclusion. Even without compression, pedicle screws passing through the NCC in immature pigs disturb spinal canal growth significantly. Clinical relevance for young children should be studied further.

Spontaneous rupture of the tibialis anterior tendon in a patient with psoriasis.

A very rare case of spontaneous rupture of the tibialis anterior tendon diagnosed by MR imaging is presented. The tendon rupture occurred in a patient with recent onset psoriasis of both shins who used a corticosteroid cream (0.1% of methylprednisolone aceponate) for his skin lesions during the last 3 months before the incident causing tendon rupture. This is the first report of a spontaneous tendon rupture in a patient with psoriasis.

MR imaging of meniscal bucket-handle tears: a review of signs and their relation to arthroscopic classification

Abstract. Our objective was to review the MR imaging signs of meniscal bucket-handle tears and assess the relevance of these signs to the arthroscopic classification of displaced meniscal tears. Forty-five menisci in 42 patients who had a diagnosis of bucket-handle tear either on MR imaging or on subsequent arthroscopy (in which Dandys classification of meniscal tears was used) were retrospectively analyzed for MR imaging findings of double posterior cruciate ligament (PCL), fragment within the intercondylar notch, absent bow tie, flipped meniscus, double-anterior horn, and disproportional posterior horn signs. Arthroscopy, which was considered as the gold standard, revealed 41 bucket-handle tears (either diagnosed or not diagnosed by MR imaging) in 38 patients (33 males, 5 females). There was a stastistically significant male preponderance for the occurrence of meniscal bucket-handle tears. Overall, sensitivity and positive predictive value of MR imaging for the detection of meniscal bucket-handle tears were calculated as 90%. Common MR imaging signs of meniscal bucket-handle tears in arthroscopically proven cases of such tears were the fragment in the notch and absent bow tie signs (98% frequency for each). Double-PCL, flipped meniscus, double-anterior horn, and disproportional posterior horn signs, however, were less common (32, 29, 29, and 27%, respectively). An arthroscopically proven bucket-handle tear was found in all patients who displayed at least three of the six MR imaging signs of meniscal bucket-handle tears. The presence of three or more MR imaging signs of meniscal bucket-handle tears is highly suggestive of this condition.

MR imaging of the anterior intermeniscal ligament: classification according to insertion sites

Abstract. Our objective was to study the frequency of anterior intermeniscal ligament on MR imaging and to make a classification according to its insertion sites on MR images. Sagittal T1-weighted and thin-section transverse T2*-weighted MR images of the knee were prospectively evaluated in 229 subjects without significant synovial effusion or total rupture of the anterior cruciate ligament. By using thin-section transverse images, the ligament was classified into three types according to its insertion sites (type A: between anterior horns of medial and lateral menisci; type B: between anterior horn of medial meniscus and anterior margin of lateral meniscus; type C: between anterior margins of medial and lateral menisci). On sagittal images location of the ligament was determined with respect to a line drawn between anterior of the tibial epiphysis and posterior of the intercondylar notch to look for a relation between its type on transverse images and location on sagittal images. Separately, arthroscopy was made in 36 patients to verify the MR assessment of the presence of the ligament. Anterior intermeniscal ligament was found in 53% of the subjects. Type B was the most common group (58%). Magnetic resonance imaging has a sensitivity and a specificity of 67 and 100%, respectively, in the detection of the ligament. Types A and C had a statistically significant location posterior and anterior, respectively, to the master line on sagittal images. In arthroscopy, the ligament was either cord-like (67%) or flat (33%) in appearance. Routine sagittal MR images can help identify anterior intermeniscal ligament.

MR imaging in squamous cell carcinoma of the head and neck with no palpable lymph nodes

Purpose: To assess the efficacy of MR imaging in the detection of lymph node metastasis in patients with no palpable lymph nodes (“N0 neck”) who have squamous cell carcinoma of the head and neck region. Material and Methods: MR neck imagings in 18 patients who underwent neck dissection (bilaterally in 2) for squamous cell carcinoma of the head and neck region were examined preoperatively for the purpose of detecting lymph node metastases. The imaging features taken into consideration were: size (cutoff point 10 mm), grouping, presence of central necrosis, and appearance of extracapsular spread. The MR examinations comprised spin-echo T1- and T2-weighted sequences. The MR findings were compared with those of surgery and histopathological examination. Results:) MR suggested metastatic lymph node involvement in 5 necks. In 2 of these, central necrosis was seen in the enlarged lymph nodes. In a third, a grouping of the lymph nodes was noted. Extracapsular spread was not present. Histopathological examination revealed metastatic lymph nodes in 7 of the 20 necks, the rate of clinically occult disease being 35%, and 4 of them had been accurately graded by MR. There was one false-positive MR examination. The MR sensitivity was 57.1% and specificity 92.3%. Conclusion: MR may reveal metastatic lymph nodes in patients with no clinical evidence of metastasis. However, conventional MR techniques are not always sufficient for decision-making on surgery in cases of “N0 neck”).

Water-lily sign on MR imaging of primary intramuscular hydatidosis of sartorius muscle

Primary hydatidosis of muscle is very rare and can cause a variety of diagnostic problems, especially in the absence of typical radiologic findings. This is the report of a case of primary intramuscular hydatid cyst in a 35-year-old woman, who presented with a 1-year history of a painless lump in the distal left thigh. The authors document the pathognomonic water-lily sign that has not previously been reported in a case of intramuscular hydatid disease.

Spinal cord compression due to epidural extramedullary haematopoiesis in thalassaemia: MRI.

Abstract Spinal epidural extramedullary haematopoiesis is very rare in thalassaemia. A 27-year-old man with thalassaemia intermedia presented with symptoms and signs of spinal cord compression. MRI showed a thoracic spinal epidural mass, representing extramedullary haematopoietic tissue, compressing the spinal cord. Following radiotherapy, serial MRI revealed regression of the epidural mass and gradual resolution of spinal cord oedema.