The diagnostic value of susceptibility-weighted imaging for identifying acute intraarticular hemorrhages.

PURPOSE: To evaluate the diagnostic performance of susceptibility-weighted imaging (SWI) in identifying acute intraarticular hemorrhages and differentiating blood from other types of joint effusions. METHODS: Thirty-two patients (21 men, 11 women; mean age 38.7 ± 16.5 SD) clinically suspected of having joint effusion were prospectively included. All the patients underwent both conventional MRI and SWI. Two radiologists independently reviewed the conventional MRI images and scored the likelihood of intraarticular hemorrhage using a 5-level scoring system. Immediately thereafter, SWI images of each patient were also provided for the radiologists, and the scoring was repeated evaluating the conventional MRI and SWI images together. The patients underwent joint aspiration or surgical operation as the reference standard. The area under the curve (AUC) of conventional MRI and conventional MRI + SWI methods were calculated and compared. The weighted kappa analysis was used to evaluate the interobserver agreement. RESULTS: Traumatic knee injury comprised the majority of study sample. Eighteen out of 32 of the patients were proven to have intraarticular hemorrhage. Using the conventional MRI, reader 1 and 2 achieved AUCs of 0.67 (p = 0.09) and 0.53 (p = 0.76), respectively. Following the addition of SWI, reader 1 and 2 achieved AUCs of 0.96 (p = 0.0001) and 0.95 (p = 0.0001), respectively, and interobserver agreement improved from Κ = 0.61 to Κ = 0.93. Accordingly, difference between the AUCs was 0.28 (p = 0.003) and 0.42 (p = 0.0001) for reader 1 and 2, respectively. CONCLUSIONS: If confirmed by future studies, SWI enables the reliable and accurate diagnosis of acute intraarticular hemorrhages.

Osteoid osteoma of the second metatarsal bone diagnosed on MRI: A case report and literature review.

Osteoid osteoma is a relatively common benign bone tumor that is most frequently seen on the appendicular skeleton in adolescents and young adults. Here we present the case of a 14-year-old boy presenting with a 10 month history of pain in his left foot which had been misdiagnosed as stress fracture due to its unusual clinical presentation. Magnetic resonance imaging of the left foot revealed a bone lesion with typical features of the osteoid osteoma on the distal part of the second metatarsal bone. The lesion was surgically removed and the diagnosis of osteoid osteoma was confirmed by post-surgical histopathologic examination of the resected section. The patient reported a substantial relief in his pain 4 weeks following the surgical operation.

Accuracy of diffusion-weighted imaging in discriminating atypical vertebral haemangiomas from malignant masses in patients with vertebral lesions: a cross-sectional study.

PURPOSE: Vertebral haemangiomas are incidental findings in imaging modalities. Atypical haemangiomas are haeman-giomas rich in vascular tissue, and they are found to be hypointense in T1 sequences and hyperintense in T2 sequences, mimicking the findings of metastatic lesions. In the present study we aim to evaluate the ability of diffusion- weighted imaging to differentiate these two groups of vertebral lesions. MATERIAL AND METHODS: In the present cross-sectional study, a total of 23 lesions were included, including 10 haemangiomas and 13 malignant lesions. Diffusion-weighted imaging was used to compare atypical haemangiomas and metastatic lesions. The apparent diffusion co-efficient was determined for each lesion, and then the mean of each group was calculated. The means were then compared. Receiver operating characteristic analysis was used to determine a cut-off ADC value to differentiate these lesions. RESULTS: The difference between the mean age of the two groups was not significant. The mean ADC value for atypical haemangiomas was 1884 ± 74 × 10-6 mm2/s and 1008 ± 81 × 10-6 mm2/s for the malignant lesions. The difference between the two groups was statistically significant (p < 10-3). ROC curve analysis determined an ADC value of 958 × 10-6 mm2/s to be able to differentiate between atypical haemangiomas and malignant lesions. CONCLUSIONS: Diffusion-weighted MRI could be used to differentiate between atypical haemangiomas and malignant metastatic lesions.

Clinical and histopathological outcome of cervical and chest MRI involving non-MRI-conditional cardiac pacemakers: a study using sheep models.

AIM: To examine the clinical and histopathological consequences of MRI in sheep implanted with non-MRI-conditional cardiac pacemakers. MATERIALS AND METHODS: Under general anesthesia, active fixation leads of two dual-chamber, non-MRI-conditional cardiac pacemakers (St. Jude Medical and Medtronic) were implanted either at the right ventricular apex or at the right atrium of two male sheep and connected to the V and A channels of the pacemakers, respectively. The generators were placed in cervical subcutaneous pockets. On day 5, both sheep underwent 1.5 T cervical and chest MRI with continuous electrocardiogram monitoring. Obtained sequences were T1-weighted (T1W), T2-weighted (T2W), T2-gradient echo and diffusion weighted (DW). The employed modes were OVO, VOO and VVI for one sheep and OAO, AOO and AAI for the other (unipolar and bipolar configuration of pacing and sensing for both). Battery impedance, pacing lead impedance, intrinsic amplitude and capture thresholds were checked at baseline and after each sequence, as well as 48 h after imaging. Histopathological examination of the cardiac tissue around the lead tip was performed 4 weeks post-imaging. RESULTS: No significant changes in device position or configuration were observed during or after MRI. Clinical outcome was uneventful in both sheep. Minor inflammatory and necrotic changes were reported after histopathological examination of the cardiac tissue around the lead tip. CONCLUSION: 1.5 T MRI of two implanted non-MRI-conditional pacemakers was found safe in terms of device configuration and stability, clinical outcome and cardiac tissue histopathological findings.

The Effect of Females' Reproductive Factors on Pituitary Gland Size in Women at Reproductive Age.

Background and Objectives: The brain imaging of the pituitary gland in females has shown a change in pituitary size and volume in the female's population. It has been proven that the pituitary gland is affected by pregnancy, giving birth, and hormone-related factors. Therefore, this study aimed to evaluate the factors which may have an impact on the pituitary size in females at reproductive age and compare the pituitary size in females with a history of pregnancy, those at the postpartum period, and nullipara females. Materials and Methods: This population-based study was conducted on 208 healthy women aged 12-55 years old. Participants underwent cranial Magnetic resonance imaging (MRI), and pituitary diameters (craniocaudal, anteroposterior, and transverse) and volume were measured for each subject. The correlation of age, gravity, parity, lactation, and intake of oral contraceptives with pituitary size were analyzed. Results: One-hundred and eighty females met the criteria for participation. The pituitary volume correlated negatively with hormone-related factors. The gravity (r = -0.35) and parity (r = -0.35) had significant negative effects on the pituitary volume (p < 0.001). The use of oral contraceptives and lactation were also in negative correlation with the pituitary volume (r = -0.20, p = 0.006, r = -0.56, p < 0.001, respectively). The craniocaudal diameter was also affected by gravity (r = -0.62), parity (r = -0.57), intake of contraceptives (r = -0.32), and lactation (r = -0.70), p < 0.001. The anteroposterior diameter of the pituitary gland associated significantly with gravity (r = -0.19, p = 0.009), parity (r = -0.20, p = 0.007), and lactation (r = -0.25, p = 0.001). The transverse diameter of the pituitary gland also related negatively with reproductive factors such as gravity (r = -0.15, p = 0.04), parity (r = -0.17, p = 0.02), and lactation (r = -0.17, p = 0.02). The pituitary gland of nullipara females was the greatest in size. Recent pregnancy led to increased craniocaudal and anteroposterior diameters. Conclusions: In this study, we found a negative effect of pregnancy and giving birth on pituitary size. Nullipara females were found to have the greatest pituitaries, even greater than the females in the postpartum period.

Serum thyroid-stimulating hormone level and relation with size of hippocampus in patients with mild cognitive disorders.

BACKGROUND: Cognitive disorders and dementia are common problems, and Alzheimer's disease is one of the major leading causes of death worldwide. Thyroid hormone disorders as a common problem effect on hippocampus size which as a prognostic factor in dementia. The aim of the present study was to investigate the relationship between serum thyroid-stimulating hormone (TSH) level and the size of hippocampus in patients with mild cognitive disorders. MATERIALS AND METHODS: In a descriptive-analytical study, 41 patients with symptoms of mild cognitive disorders whom referred to take the brain magnetic resonance image (MRI) in a radiology center under the direction of Tabriz University of Medical Sciences (Tabriz, Iran) were evaluated. The right and left hippocampal and brain volume was calculated by MRI at coronal T1-weighted. Serum TSH level was also measured in these patients. Correlation between serum TSH level and hippocampal volume size was evaluated. RESULTS: Male to female ratio was 1.05:1 with mean age of 54.09 ± 3.11 years. Mean serum TSH level of patients was 1.55 ± 1.45 uU/ml. The right and left hippocampal volumes were 1.61 ± 0.42 and 1.62 ± 0.39 ml, respectively. There were slight negative correlations between the right and left hippocampal volumes with TSH level (r = -0.133 and r = -0.092, respectively). Correlations between the right and left hippocampal volumes with TSH level were not statistically significant (P = 0.406, P = 0.566, respectively). CONCLUSION: Based on findings of the present study, there was a weak negative correlation between serum level of TSH with the right and left hippocampal and brain volume ratio, but the correlation was not statistically significant. It seems that controlling of clinical or subclinical hypothyroidism may have a role in slowing of dementia progression and also have a preventive role.

Diffusion-weighted magnetic resonance imaging in differentiating acute infectious spondylitis from degenerative Modic type 1 change; the role of b-value, apparent diffusion coefficient, claw sign and amorphous increased signal.

OBJECTIVE: To examine the effect of using different b-values on the utility of diffusion-weighted (DW) MRI in differentiating acute infectious spondylitis from Modic type 1 and the discriminative accuracy of related apparent diffusion coefficient (ADC), claw-sign and amorphous increased signal. METHODS: 43 patients with equivocal diagnosis of acute infectious spondylitis/Modic type 1 by using MR images were prospectively studied. The discriminative accuracy of DW MRI using three b-values of 50, 400, 800 s mm(-2), ADC, claw sign and amorphous increased signal was examined. RESULTS: DW MRI differentiated infectious spondylitis from Modic type 1 change most accurately when a b-value of 800 s mm(-2) was chosen [sensitivity, 91.7%; specificity, 96.8%; positive-predictive value (PPV), 91.7%; negative-predictive value (NPV), 96.8%; and accuracy, 95.3%]. The optimal cut-off ADC value was 1.52 × 10(-3) mm(2) s(-1) (sensitivity, 91.7%; specificity, 100%; PPV, 100%; NPV, 96.9%; and accuracy, 97.7%). Best visualized at a b-value of 50 s mm(-2), claw sign (for degeneration) and amorphous increased signal (for infection) were 100% accurate. CONCLUSION: Should DW MRI be used in differentiating acute infectious spondylitis from degeneration, large b-values are required. With low b-values, however, claw sign and amorphous increased signal are very accurate in this regard. ADVANCES IN KNOWLEDGE: DW MRI using large b-values could be used in differentiating acute infectious spondylitis from Modic type I.

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

BACKGROUND: magnetic resonance imaging (MRI) as a noninvasive diagnostic tool may help clinicians in the evaluation of injuries to menisci and ligaments. PURPOSE: this study assessed the associations between type of trauma to knee joint, bone bruise, fracture and pathological joint effusion with injuries to menisci and ligaments of knee joint. METHODS: we reviewed knee joint MRI of 175 patients aged less than 45 years old who were referred to MRI center of our University. RESULTS: statistical analysis showed that tearing of medial meniscus (MM) is significantly more common in sport related trauma (p= 0.045) but tearing of medial collateral ligament (MCL) is significantly more common in non-sport related trauma (p= 0.005). Existence of bone bruise in knee MRI is negatively associated with tearing of medial meniscus (MM) (p=0.004) and positively associated with tearing of anterior cruciate ligament (ACL) (p=0.00047) and medial collateral ligament (MCL) (p = 0.0001). Existence of fracture is associated with decreased risk of the tearing of ACL and MM (p=0.04, p=0.001 respectively). Pathologic joint effusion is significantly more common in ACL and MCL tearing (p=0.0001, p=0.004 respectively). CONCLUSIONS: as diagnostic clues, bone bruise, fracture and joint effusion may help radiologists for better assessment of injury to menisci and ligaments in MRI of patients with knee trauma.

Orientation of the facet joints in degenerative rotatory lumbar scoliosis: an MR study on 52 patients.

BACKGROUND: Because of a degenerative component, degenerative rotatory scoliosis seems different from congenital and idiopathic subtypes of the disease. This study aims to examine the orientation of facet joints, as a known cause of degeneration, in patients with degenerative rotatory scoliosis. METHODS: Lumbar magnetic resonance (MR) images and plain radiographs of 52 symptomatic patients (mean age, 50.17 years) with degenerative rotatory lumbar scoliosis (mean curve, 19.22 degrees) and 50 healthy individuals were reviewed. Facet joint angles in rotated segments and the minimum neural foramen width at all lumbar levels were measured by three observers and the average was recorded. RESULTS: The maximum vertebral rotation was most frequent at L4-L5 (75 %), and the majority was of type I (84.6 %) according to the Nash-Moe classification. At all lumbar spinal levels the mean facet joint angles were significantly higher on the side of rotation (L2-L3, 57.92 degrees; L3-L4, 45.00 degrees; L4-L5, 43.88 degrees) compared to those on the contralateral side (L2-L3, 20.42 degrees; L3-L4, 15.48 degrees; L4-L5, 13.12 degrees) and in controls (L2-L3, 30.21 degrees; L3-L4, 40.81 degrees; L4-L5, 45.20 degrees) (p < 0.001 for all comparisons). The mean facet joint angle increased significantly from L4-L5 to L2-L3 in cases and reversely in controls. The mean minimum neural foramen width was 1.29 ± 0.85 mm on the side of rotation, 5.50 ± 1.09 mm on the contralateral side, and 6.78 ± 1.75 mm in controls (p < 0.001). CONCLUSIONS: Substantial asymmetries and abnormal orientations in facet joints were documented in patients with degenerative rotatory lumbar scoliosis. Such asymmetries may adversely affect neural foramen width.

Fetal Nasal Bone Status In Iranian Women Undergoing First-Trimester Screening For Trisomy 21: A Review and an Observational Study.

BACKGROUND: Failed visualization of the fetal nasal bone (NB) by ultrasound at 11 - 14 weeks of gestation is strongly associated with chromosomal abnormalities. Meanwhile, the incidence of the absent fetal NB in normal fetuses in the first trimester in mothers of different ethnic origins differs significantly. It is, therefore, important to assess ethnic variations in the first-trimester visualization of the fetal NB before introducing this marker into routine screening programs for aneuploidy. OBJECTIVES: The objectives of this study were to determine the NB length and the prevalence of the NB absence as well as calculating the likelihood ratio (LR) for the absence of the NB in normal fetuses of Iranian women undergoing first-trimester screening for trisomy 21. PATIENTS AND METHODS: In 767 normal fetuses, the fetal profile was examined by ultrasound for the absence/presence of the NB. The NB length was also measured, and the LR for the NB absence was also determined. RESULTS: The NB was absent in 2/767 (0.26%) of the fetuses. The mean length of the NB was 3.6 ± 0.69 mm for the fetuses of 11 - 14 weeks gestational age. The LR value of the absent NB was equal to 250 in the normal fetuses of the Iranian population living in the North-West provinces. CONCLUSION: The low prevalence of the NB absence in normal fetuses in the present study is compatible with the larger size of the NB in Iranian people compared to other communities. Meanwhile, the reference range of the NB length in normal Iranian fetuses was established so that basic data could be recorded for further studies regarding the absence or presence of the NB in screening for chromosomal abnormalities (Down syndrome) within the Iranian population.

Redundant nerve roots of the cauda equina in lumbar spinal canal stenosis, an MR study on 500 cases.

PURPOSE: The purpose of this study was to evaluate magnetic resonance (MR)-detected redundant nerve roots (RNRs) of the cauda equina in patients with lumbar spinal canal stenosis. METHODS: A total of 500 lumbar MR studies in patients with lumbar spinal canal stenosis were reviewed for the presence and characteristics of RNRs of the cauda equina. The length of the RNRs relative to the height of the upper vertebral body of the level of the stenosis was used as a prognostic indicator. RESULTS: RNRs were detected in 15% of the patients, the majority above the level of the stenosis (85%) and loop shaped (72%). Advanced age (i.e., ≥56 years old, odds ratio=1), a lumbar spinal canal stenosis at L2-4 (odds ratio=2.5), and the presence of an intracanal protuberance with sharp margin in the site of the stenosis (odds ratio=7.2) were independent risk factors for the development of RNRs. A direct, significant correlation was found between the relative length of the RNRs and patients' age (Pearson r=0.36, p=0.001). The mean relative length of the RNRs was significantly higher in patients with RNRs located above the level of the stenosis than those with RNRs located below the site of the block. The degree of stenosis was associated with neither the presence nor the relative length of the RNRs. CONCLUSIONS: With an occurrence rate of 15%, RNRs of the cauda equina are not uncommon in cases with lumbar spinal canal stenosis. Advanced age, a canal stenosis at L2-4, and the presence of a sharp intracanal protuberance in the site of the stenosis are the related risk factors. Patients' age and the location of RNRs may be of prognostic value.

Magnetic resonance imaging of Whipple's disease confined to the CNS presenting with multiple intracerebral mass lesions.

We report a patient diagnosed with Whipple's disease (WD) who presented only with neurological symptoms. Neuroimaging (MRI) showed lesions with marked mass effect similar to infiltrative tumors, which were hypersignal on long TR and hyposignal on short TR images, located in several areas of the brain. In serial controls, lesions resolved with gliosis and atrophic changes as well as migration of active infiltrative-like lesions to new areas. MR findings of the brain WD are discussed, which confirmed by stereotactic brain biopsy. Familiarity with the range of possible MR imaging appearances of WD enables the radiologist to place WD more effectively on the differential diagnosis which motivates the clinician to consider both the diagnosis and early initiation of treatment; so, this may significantly impact outcome. Moreover, repeated MR investigations may serve as a valuable method to evaluate efficacy of treatment and long term follow-up of WD involving the CNS.

Supine spinal magnetic resonance imaging with straightened lower extremities in spondylolisthesis: a comparison with the conventional technique.

OBJECTIVES: To compare the degree of slip in spondylolisthesis on supine magnetic resonance (MR) images obtained with flexed and straightened lower extremities. METHODS: Supine spinal MR studies were performed in 100 cases of symptomatic spondylolisthesis with flexed and then straightened lower extremities. The angle of lumbar lordosis (by Cobb's method) and the degree of slip (by Taillard's method) were compared between the two sets of images. RESULTS: The mean angle of lumbar lordosis increased from 51.65±8.57° on MR images with flexed lower limbs to 57.39±9.05° on MR images with straightened lower limbs (p<0.001; mean percent increase: 11.51%). Similar change was also observed for the mean degree of slip (from 25.80±7.74% to 28.68±7.93%, p<0.001; mean percent increase: 12.60%). After MR imaging with straightened lower extremities 22 out of 54 initially grade I cases had grade II disease (p<0.001). CONCLUSIONS: Supine magnetic resonance imaging with straightened lower extremities detects higher degree of slippage in symptomatic patients with spondylolisthesis compared to conventional MRI with flexed lower extremities.

End plate disproportion and degenerative disc disease: a case-control study.

STUDY DESIGN: Case-control. PURPOSE: To determine whether a disproportion between two neighboring vertebral end plates is associated with degenerative disc disease. OVERVIEW OF LITERATURE: Recently, it has been suggested that disproportion of the end plates of two adjacent vertebrae may increase the risk of disc herniation. METHODS: Magnetic resonance (MR) images (n=160) with evidence of grades I-II lumbar degenerative disc disease (modified Pfirrmann's classification) and normal MR images of the lumbar region (n=160) were reviewed. On midsagittal sections, the difference of anteroposterior diameter of upper and lower end plates neighboring a degenerated (in the case group) or normal (in the control group) intervertebral disc was calculated (difference of end plates [DEP]). RESULTS: Mean DEP was significantly higher in the case group at the L5-S1 level (2.73±0.23 mm vs. 2.21±0.12 mm, p=0.03). Differences were not statistically significant at L1-L2 (1.31±0.13 mm in the cases vs. 1.28±0.08 mm in the controls, p=0.78), L2-L3 (1.45±0.12 mm in the cases vs. 1.37±0.08 mm in the controls, p=0.58), L3-L4 (1.52±0.13 mm in the cases vs. 1.49±0.10 mm in the controls, p=0.88), and L4-L5 (2.15±0.21 mm in the cases vs. 2.04±0.20 mm in the controls, p=0.31) levels. The difference at the L5-S1 level did not remain significant after adjusting for body mass index (BMI), which was significantly higher in the patients. CONCLUSIONS: End plate disproportion may be a significant, BMI-dependent risk factor for lumbar degenerative disc disease.

Association between obstetric conjugate diameter measured by transabdominal ultrasonography during pregnancy and the type of delivery.

BACKGROUND: Normal morphological features of the maternal pelvis are an important prerequisite to vaginal delivery. OBJECTIVES: We aimed to evaluate the association between obstetric conjugate diameter (OCD) measured by ultrasonography and the type of delivery, vaginally (V) or by cesarean (C) section. PATIENTS AND METHODS: Pelvimetry was performed in 200 primigravid women for fetal cephalic presentation. The OCD was measured twice by transabdominal ultrasonography during 25-30 weeks and 30-35 weeks of pregnancy. RESULTS: The mean OCD of both sonographies in groups V and C was 125.51± 8.35 mm (105-144.5) and 112.99 ± 8.53 mm (96-134.5), respectively, which was significantly lower in group C (P<0.001). The values of OCD between the first and second measurements were not different significantly (P=0.065). C-section was indicated in 65 (32.5%) mothers. The optimal cut-off point for the OCD in the prediction of vaginal delivery was ≥ 119.75 mm, with a sensitivity and specificity of 80% and 78.5%, respectively. CONCLUSION: The US measurement of OCD might be an accurate method that almost always remains constant during late pregnancy; it is easy to measure and might be confidentially employed for predicting C-section, but needs more precise studies to be used widely.

Bilateral primary breast lymphoma in a teenage girl with multi-organ involvement.

We present 16 years old girl with primary breast lymphoma involving the both breasts simultaneously and co-incidence of central nervous system (CNS) involvement which originated from the breast, in addition to evidence of lymphoma in multi-organ such as skin, mediastinum and some abdominal viscera. Bilaterality has been observed in some series, but reports are few and series are often very small. Radiologic features may be indistinguishable from those of the other breast malignancies, but it can be concluded that primary involvement of the breast with lymphoma should be considered when breast mass or inflammatory changes occur in a patient without any previously diagnosed lymphoma. The clinical behavior, imaging and therapeutic procedures are discussed. The findings of this report may have clinical impact on oncologists or that may alter the disease concept of bilateral breast lymphoma.

Thrombolytic therapy for cerebral vein thrombosis in antiphospholipid syndrome secondary to systemic lupus erythematosus.

A 20-year-old woman was admitted to a Gynecology Hospital in her 6(th) month of pregnancy for high blood pressure and tonic-clonic seizure. Primary diagnosis was eclampsia, and for that reason she underwent cesarean section. She also had headache on frontal and parietal areas without nausea or vomiting. There was not a focal neurological sign. Rheumatology consultation was requested. Systemic lupus erythematosus and secondary antiphospholipid (APS) was confirmed. The patient had headache that continued several days after cesarean section, therefore, brain magnetic resonance imaging (MRI) and magnetic resonance venography (MRV) were performed, and cerebral vein thrombosis was documented. Distal segment of right lateral sinus and sigmoid sinus were not appeared in brain MRV. Abnormal hypersignal intensity of right lateral sinus/coronal T2 was detected. Thrombolytic therapy with 20 mg tissue plasminogen activator on right sigmoid and transverse sinus was performed by an interventional neurologist. After this procedure, the patient(')s headache healed and she was discharged in a good condition.

Diagnostic value of ultrasonography and magnetic resonance imaging in ulnar neuropathy at the elbow.

Aim. To evaluate the diagnostic value of ultrasonography and magnetic resonance imaging (MRI) in patients with ulnar neuropathy at the elbow (UNE). Methods. We prospectively performed electrodiagnostic, ultrasonographic, and MRI studies in UNE patients and healthy controls. Three cross-sectional area (CSA) measurements of the ulnar nerve at multiple levels along the arm and maximum CSA(-max) were recorded. Results. The ulnar nerve CSA measurements were different between the UNE severity grades (P < 0.05). CSA-max had the greatest sensitivity (93%) and specificity (68%). Moreover, CSA-max ≥10 mm(2) defined the severe UNE cases (sensitivity/specificity: 82%/72%). In MRI, ulnar nerve hyperintensity had the greatest sensitivity (90%) and specificity (80%). Conclusion. Ultrasonography using CSA-max is sensitive and specific in UNE diagnosis and discriminating the severe UNE cases. Furthermore, MRI particularly targeting at increased signal of the ulnar nerve can be a useful diagnostic test of UNE.

Comparison of maximum signal intensity of contrast agent on t1-weighted images using spin echo, fast spin echo and inversion recovery sequences.

BACKGROUND: MRI is not able to directly measure the concentration of contrast agent. It is measured indirectly from the signal intensity (SI). It is very important to know how much contrast agent should be injected to receive a maximum SI in the region of interest (ROI). OBJECTIVES: The aim of this study was to investigate the maximum relationship between contrast concentration and signal intensity (SI) on T1-weighted images using spin echo (SE), fast spin echo (FSE) and inversion recovery (IR) sequences. MATERIALS AND METHODS: To assess the relationship between SI and concentration, a water-filled phantom containing vials of different concentrations of gadolinium DTPA (Gd-DTPA) (0 to 19.77 mmol/L) or a constant concentration (1.2 mmol/L) of contrast agent was used. The vials of constant concentration were used to measure coil nonuniformity. The mean SI was obtained in the ROI using T1-weighted images. All studies were carried out using a 0.3 T clinical MR scanner with a standard head coil. RESULTS: This study shows that maximum SI will appear at different ranges in different sequences. The maximum SI can be seen at concentrations of 5.95, 4.96 and 3.98mmol/L for SE, FSE and IR, respectively. CONCLUSION: Using standard imaging parameters, each MRI sequence reaches its maximum SI in a specific contrast concentration, which is highest in SE and least in IR in a comparison between SE, FSE and IR sequences.

Extramedullary plasmacytoma presenting as a solitary mass in the intracranial posterior fossa.

A patient with a 3-month history of headache refractory to pain medication was admitted. The CT scan and MRI showed evidence of a posterior fossa mass. This was pathologically confirmed as an extra medullary plasmacytoma (EMP). He had a pathologic fracture of the left humerus 7 years ago while the radiologist was unaware at the time of diagnosis. A solitary bone plasmacytoma (SBP) was the cause of the pathologic fracture. This report includes the first description of MRI findings in a patient with a rare-incidence intracranial solitary extra medullary plasmacytoma (SEP) in Iran. There is a striking similarity between the features of intracranial SEP and meningiomas. Intracranial SEP, although rare, should be included in the differential diagnosis of brain tumors in areas where meningiomas commonly arise. The MRI findings and differential diagnosis of plasmacytoma are reviewed. Before this case report, only few cases have been reported in the literature. Nonetheless, this is the first report of posterior fossa EMP from Iran.