Magnetic Resonance Criteria Research Articles

Reliability of Magnetic Resonance Imaging Criteria for the Preoperative Assessment of Rotator Cuff Tears: A Systematic Review

Background: Magnetic resonance (MR) imaging is the most common modality for assessment of the rotator cuff before and after surgery. Several classifications have been described aiming to define main tear characteristics. However, there is still confusion when it comes to the reliability of those classifications. Purpose: (1) To identify all MR classifications available in the literature for preoperative assessment of rotator cuff tears, (2) to summarize available data on the reliability of identified classifications, and (3) to assess the methodological quality of reliability studies. Study Design: Systematic review; Level of evidence, 4. Methods: This systematic review was conducted following the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. All studies reporting MR assessment in patients with a superior or posterosuperior rotator cuff tear were included. After identification of the available MR criteria, reliability studies were analyzed. Descriptive statistics were used to summarize findings. Methodological quality was assessed using the Quality Appraisal of Reliability Studies checklist. Results: A total of 75 studies were included in this review. Eight categories of outcomes could be identified. Of the total, 62 studies reported interobserver reliability whereas 32 reported intraobserver reliability of some of the identified criteria. Each category reflected a variety of reliability, ranging from poor to excellent agreement. MR proved to be a reliable imaging modality to detect the structural integrity of the posterosuperior cuff, especially in cases of full-thickness tear; it was also reliable in terms of tear width and length and muscle atrophy based on a tangent sign or Thomazeau classification. All other classifications did not prove acceptable reliability. Methodological quality was high for 23 articles and moderate for 14. Conclusion: Preoperative MR is a reliable imaging modality to identify full-thickness tears, measure tear size and morphology, and identify muscle atrophy with tangent sign or Thomazeau classification. All other outcomes and classifications did not show acceptable reliability; therefore, caution is needed when using them for preoperative evaluation of a rotator cuff tear.

Computerized predictive model for differential diagnosis of normal pressure hydrocephalus based on complex analysis of MRI image

Background. The main problem is to differentiate idiopathic normal pressure hydrocephalus (iNPH) with other neurodegenerative diseases accompanied by similar clinical presentation. For this purpose, a number of neuroimaging and invasive methods were proposed. The study objective is to assess most reliable magnetic resonance (MR) symptoms of iNPH and to create a prognostic model for differential diagnosis of iNPH by these criteria. Materials and methods. MR-data of 213 iNPH, 144 neurodegenerative (Alzheimer disease, Parkinson disease and early mild cognitive impairment) patients and 79 healthy age-matched controls were retrospectively analyzed. Following criteria were assessed: Evans Index, size of the third ventricle, size of temporal horns, disproportionately enlarged subarachnoid space hydrocephalus, focal convexital sulci enlargement, callosal angle, periventricular hyperintensities, focal subcortical gliosis and perivascular spaces enlargement. One-way ANOVA was used to explore differences between groups. Classification matrix was formed by discriminant analysis. Results. Differential model was established and Excel-tab-calculator was created for complex computed assessment of MR data and differential diagnosis of iNPH patients. Prognostic accuracy of model for iNPH reaches 99.5 %, for degenerative disorders – 89 %, common diagnostic accuracy is 92 %. Conclusion. Advantages of complex approach for assessment of MR-data in iNPH patients were underlined. Prognostic model for prediction of iNPH based on MR criteria was established.

Complex US adnexal masses during pregnancy: Is pelvic MR imaging accurate for characterization?

ObjectiveTo retrospectively evaluate the accuracy of pelvic magnetic resonance (MR) imaging for the characterization of complex sonographic adnexal masses discovered in women during pregnancy. Study designThe study population comprised 31 pregnant women (median age: 32 years (range: 19–42); mean gestation age of 16 weeks) referred to our institution for MR imaging for characterization of an adnexal mass discovered incidentally during routine ultrasound (US) for other indications. The population comprised of 31 women, with 36 adnexal lesions (mean size: 103mm [range: 20–290]), of which 27 were benign and 9 were malignant masses. Prospective US and MR reports were reviewed to determine the presence of a benign or malignant lesion. Two radiologists (R1 and R2) blinded to the final outcome, retrospectively evaluated the MR images using the criteria based on the ADNEXMR-SCORE and classified the lesion as benign or malignant. The reference standard was surgical pathology or at least a 1-year imaging follow-up. ResultsProspective US and MR imaging correctly identified the diagnosis in 27/36 (75%) (95% confidence interval (CI): 58.9%–86.2%) and in 32/36 (88.9%) (95% CI: 74.6%–95.6%) of lesions, respectively. MR imaging with ADNEXMR-SCORE allowed a correct diagnosis in 32/36 (88.9%) (95% CI: 74.6%–95.6%) of lesions for R1 and in 30/36 (83.3%) (95% CI: 68.1%–92.1%) of lesions for R2. The sensitivities and specificities of MR imaging using the MR ADNEXMR-SCORE were 100% (95% CI: 70.1%–1000%) for both readers and 85.1% (95% CI: 67.5%–94%) and 77.7% (95% CI: 59.2%–89.4%) for R1 and R2, respectively. No malignancy was classified as benign using MR criteria. The reproducibility between the two readers was almost perfect, with a kappa of 0.914. ConclusionMR imaging is highly accurate for the characterization of complex adnexal masses incidentally discovered during pregnancy. Clinical relevanceMR imaging can accurately characterize adnexal masses in pregnancy and could be useful in opting for expectant management until delivery.

Diagnosis of moyamoya disease using 3-T MRI and MRA: value of cisternal moyamoya vessels

The purpose of this study was to propose new magnetic resonance (MR) criteria of diagnosing moyamoya disease (MMD) from cisternal moyamoya vessels (MMVs) on 3-T magnetic resonance imaging (MRI)/magnetic resonance angiography (MRA) and compare the diagnostic accuracy of the existing MR criteria and the proposed MR criteria. Participants comprised 20 consecutive patients with MMD (4 males, 16 females) diagnosed clinically using conventional angiography and 20 controls (13 male and 7 female arteriosclerosis patients). In these participants, 3-T MRI/MRA was evaluated by the existing MR criteria, which use MMVs in the basal ganglia, and the proposed MR criteria, which use cisternal MMVs, and then these two criteria were statistically compared by McNemar's test. Diagnostic accuracy was 62.5% with the existing MR criteria and 97.5% with the proposed MR criteria. The proposed MR criteria was more sensitive (1.00) than the existing MR criteria (0.45), but less specific (0.95) than the existing MR criteria (1.00). The proposed MR criteria using cisternal MMVs showed significantly higher diagnostic accuracy than the existing MR criteria. We believe that our proposed MR criteria will be beneficial for diagnosing MMD.

High-b-Value Diffusion-weighted MR Imaging of Benign Hepatocellular Lesions: Quantitative and Qualitative Analysis

To analyze the signal intensity (SI) of benign hepatocellular lesions in high-b-value diffusion-weighted (DW) magnetic resonance (MR) images and to compare the apparent diffusion coefficient (ADC) values of focal nodular hyperplasias (FNHs) with those of hepatocellular adenomas (HCAs). This retrospective study was approved by institutional review board, with waiver of informed consent. Inclusion criteria were consecutive patients with diagnosed FNH or HCA who underwent MR imaging with a DW sequence of the liver at three b values, 0, 150, and 600 sec/mm2. The final study population included 67 patients (seven men, 60 women) with 90 hepatocellular lesions (54 FNHs, 36 HCAs). The mean ADC was compared between the lesions and the liver. Receiver operating characteristic analysis was performed to evaluate the diagnostic value of ADC for differentiating HCAs and FNHs. The mean ADC value of all FNHs and HCAs was significantly lower than that of the liver (P=.004). An ADC ratio below 15% was observed in 50 of 54 (93%) FNHs and in 29 of 36 (81%) HCAs. The mean ADC value of FNHs was significantly higher than that of HCAs (P<.001). The area under the receiver operating characteristic curve was 0.760. With a cutoff value of 1.37×10(-3) mm2/sec, the sensitivity and specificity for differentiating HCA from FNH were 70% and 76%, respectively. There was no significant difference in ADC values between HCA subtypes. The SI of most FNHs and HCAs (78 of 90, 87%) increased with increasing b values, whereas none showed a decrease in SI with increasing b values. When the DW MR criteria for benign and malignant liver tumors were applied, 44 of 90 (49%) lesions would have been considered malignant lesions, whereas the other lesions (46 of 90, 51%) would have been considered indeterminate. On DW MR images, benign hepatocellular lesions often show findings that suggest restricted diffusion.

Partial tear of the anterior cruciate ligament of the knee: injury patterns on MR imaging

To describe rupture patterns of partial anterior cruciate ligament (ACL) tears on magnetic resonance (MR) imaging. MR images of 51 patients with a surgically confirmed partial ACL tear were retrospectively and independently interpreted by 2 experienced, blinded radiologists. Using previously described MR criteria, ACLs were categorized as follows: complete tear, partial tear, isolated anteromedial or posterolateral bundle tear, mucoid degeneration or normal ACL. MR interpretations were compared with the arthroscopic results as the standard of reference. Inter- and intraobserver agreements were determined using kappa (к) coefficients. On MR imaging, ACL injuries were categorized as complete tears (16-23%), partial tears (20-47%), mucoid degeneration (12-27%) or normal ACLs (18-23%). Isolated ACL bundle tears were diagnosed on MR in 6% of our patients. Accuracy of MR for the diagnosis of partial ACL tears was 25-53%. Interobserver agreement was moderate (к = 0.48-0.56). Intraobserver agreement was good (к = 0.72-0.76). MR diagnosis of a partial ACL tear is difficult because various tear patterns may be seen. Many partial tears demonstrate MR features that are indistinguishable from complete ACL tear, mucoid ACL degeneration or normal ACL. An isolated ACL bundle tear is infrequently detected on MR images.

Characterization of Complex Adnexal Masses: Value of Adding Perfusion- and Diffusion-weighted MR Imaging to Conventional MR Imaging

To retrospectively determine the value of adding perfusion-weighted (PW) and diffusion-weighted (DW) sequences to a conventional magnetic resonance (MR) imaging protocol to differentiate benign from malignant tumors. The institutional ethics committee approved this retrospective study and waived the requirement to obtain informed consent. MR images in 87 women (age range, 25-87 years) who underwent imaging before surgery for complex adnexal masses-excluding endometriomas and cystic teratomas-were analyzed. Conventional morphologic, perfusion, and diffusion MR criteria of malignancy were recorded. Three independent observers reviewed images in four steps: conventional MR images alone, conventional MR images and PW images combined, conventional MR images and DW images combined, and conventional, PW, and DW MR images combined. Receiver operating characteristic curve analysis was performed to compare the results of the readings. A recursive partitioning model was built to establish a multivariate decision tree. There was almost perfect agreement for lesion characterization regardless of the reader experiment or step considered (κ = 0.811-0.929). Area under the receiver operating characteristic curve values were higher for conventional and DW images combined, conventional and PW images combined, and conventional, DW, and PW images combined compared with conventional MR images alone (P < .05). For all readers, the accuracy of conventional, PW, and DW imaging combined was higher than that of conventional MR imaging alone for benign masses (P < .01) but not for malignant masses (P = .24). The addition of both PW and DW images led to a correct change in the diagnosis in 19% (11 of 57 patients), 23% (13 of 57 patients), and 24% (14 of 57 patients) of cases for readers 1, 2, and 3, respectively, with no incorrect changes. Conventional, PW, and DW MR imaging criteria were combined to generate a decision tree giving an accuracy of 95%. The addition of PW and DW sequences to a conventional MR imaging protocol improved the diagnostic accuracy in the characterization of complex adnexal masses.

Locally Advanced Rectal Cancer: MR Imaging for Restaging after Neoadjuvant Radiation Therapy with Concomitant Chemotherapy Part II. What Are the Criteria to Predict Involved Lymph Nodes?

To prospectively determine diagnostic performance of predictive criteria for nodal restaging after radiation therapy with concomitant chemotherapy by using ultrasmall superparamagnetic iron oxide (USPIO)-enhanced magnetic resonance (MR) imaging in patients with rectal cancer. After institutional review board approval and informed consent were obtained, 39 patients (24 men, 15 women; mean age, 64 years) with rectal cancer underwent USPIO-enhanced two-dimensional (2D) T2-weighted fast spin-echo, three-dimensional (3D) T1-weighted gradient-echo, and 3D T2*-weighted MR for restaging. Two observers evaluated nodes for border irregularity, short- and long-axis diameters, and estimated percentage of white region (<30%, 30%-50%, or >50%) within the node (3D T2*-weighted images). Ratio of the measured surface area of the white region within the black node to the measured surface area of the total node (Ratio(A)) was calculated. Signal intensity (SI) in gluteus muscle (SI(GM)) and in total node (SI(TN)) were used to calculate SI(TN)/SI(GM) ratio. Histopathologic findings were reference standard. Receiver operating characteristic (ROC) curves were compared and interobserver agreement was determined. Lesion-by-lesion analysis was feasible in 201 lymph nodes. Area under the ROC curve (AUC) of border and short- and long-axis diameters for observer 1 were 0.85, 0.87, and 0.88 and for observer 2 were 0.70, 0.89, and 0.87, respectively. AUC for estimated percentage of white region within the node, Ratio(A), and SI(TN)/SI(GM) ratio for observer 1 were 0.98, 0.99, and 0.62 and for observer 2 were 0.97, 0.98, and 0.65, respectively. AUC for USPIO-enhanced MR criteria was significantly better than AUC for conventional MR criteria (P < .01). All criteria except border irregularity and SI(TN)/SI(GM) ratio showed high interobserver agreement (kappa > 0.79). The most reliable predictors for identifying benign nodes after radiation therapy with concomitant chemotherapy by using USPIO-enhanced MR imaging for restaging in patients with rectal cancer were estimated percentage of white region within the node and Ratio(A). Measurements on standard 2D T2-weighted fast spin-echo images versus primary staging results offer reasonably good accuracy to identify benign lymph nodes after therapy.

Renal Lesions: Characterization with Diffusion-weighted Imaging versus Contrast-enhanced MR Imaging

To compare the diagnostic performance of diffusion-weighted (DW) magnetic resonance (MR) imaging with that of contrast material-enhanced (CE) MR imaging and to assess the performance of these examinations combined for the characterization of renal lesions, with MR follow-up and histopathologic analysis as the reference standards. The institutional review board waived the requirement of informed patient consent for this retrospective HIPAA-compliant study. One hundred nine renal lesions in 64 patients (46 men, 18 women; mean age, 60.7 years) were evaluated with CE MR imaging and breath-hold DW imaging performed with various b values. Renal lesions were characterized with use of CE MR criteria, and apparent diffusion coefficients (ADCs) were measured. The ADCs of benign and malignant lesions were compared at Mann-Whitney testing. Receiver operating characteristic (ROC) analysis was performed to assess the accuracy of DW imaging and CE MR imaging in the diagnosis of renal cell carcinoma (RCC). The 109 renal lesions--81 benign lesions and 28 RCCs--had a mean diameter of 4.2 cm +/- 2.5 (standard deviation). The mean ADC for RCCs (1.41 x 10(-3) mm(2)/sec +/- 0.61) was significantly lower (P < .0001) than that for benign lesions (2.23 x 10(-3) mm(2)/sec +/- 0.87) at DW imaging performed with b values of 0, 400, and 800 sec/mm(2). At a cutoff ADC of less than or equal to 1.92 x 10(-3) mm(2)/sec, the area under the ROC curve (AUC), sensitivity, and specificity of DW imaging for the diagnosis of RCCs (excluding angiomyolipomas) were 0.856, 86%, and 80%, respectively. The corresponding AUC, sensitivity, and specificity of CE MR imaging were 0.944, 100%, and 89%, respectively. Combined DW and CE MR imaging had 96% specificity. The AUC for the DW imaging-based diagnosis of solid RCC versus oncocytoma was 0.854. Papillary RCCs had lower ADCs than nonpapillary RCCs. DW imaging can be used to characterize renal lesions; however, compared with CE MR imaging, it is less accurate. DW imaging can be used to differentiate solid RCCs from oncocytomas and characterize the histologic subtypes of RCC.

Mesorectal Fascia Invasion after Neoadjuvant Chemotherapy and Radiation Therapy for Locally Advanced Rectal Cancer: Accuracy of MR Imaging for Prediction

To retrospectively assess sensitivity and specificity of magnetic resonance (MR) imaging after chemotherapy and radiation therapy for predicting tumor invasion of the mesorectal fascia (MRF) in locally advanced primary rectal cancer, by using results of histologic examination and surgery as the reference standard, and to determine morphologic MR imaging criteria for MRF invasion. The Ethical Committee of University Hospital Maastricht approved this study and waived informed consent. Two observers independently scored postchemoradiation MR images in 64 patients with rectal cancer (38 male [mean age, 60 years] and 26 female [mean age, 64 years] patients) for MRF tumor invasion with a confidence level scoring system defined by subjective criteria. In a subsequent consensus reading session, morphologic MR criteria for invasion were defined by comparing morphologic changes with histologic findings. These criteria were evaluated and compared with the subjective criteria by comparing areas under the receiver operating characteristic curves (AUCs). AUCs of postchemoradiation MR imaging for predicting MRF tumor invasion were 0.81 and 0.82 for observers 1 and 2, respectively. The following four types of morphologic tissue patterns at MR imaging were associated with whether or not MRF invasion was present at histologic examination: (a) development of fat pad larger than 2 mm (seen in no quadrants with and in four quadrants without invasion), (b) development or persistence of spiculations (seen in no quadrants with and in 22 quadrants without invasion), (c) development of diffuse hypointense "fibrotic" tissue (seen in 21 quadrants with and in 32 quadrants without invasion), and (d) persistence of diffuse iso- or hyperintense tissue (seen in 19 quadrants with and in two quadrants without invasion). AUC of postchemoradiation MR imaging for predicting MRF invasion on the basis of morphologic criteria was 0.80. There was no significant difference between the performance of subjective and morphologic criteria (P = .73-.76). Postchemoradiation MR imaging findings have moderate accuracy for predicting tumor invasion of the MRF related to the limitation in differentiating between diffuse "fibrotic" tissue with and that without small tumor foci. Specific other types of morphologic patterns at MR imaging can highly predict a tumor-free or invaded MRF.

Evaluation of pituitary microadenomas with dynamic MR imaging

Purpose: To evaluate the use of keyhole dynamic magnetic resonance (MR) imaging in the evaluation of women with borderline hyperprolactinemia. Patients and methods: We investigated 30 patients (mean age 31.6±4.3 years) with moderate hyperprolactinemia and clinically suspected microadenomas on T1-weighted spin echo (SE) sequences (repetition time (TR)/echo time (TE) 625/15 ms) with keyhole dynamic imaging and contrast enhancement of the pituitary gland. The probability of lesion presence according to MR criteria was ranked on a five-grade scale and compared with standard examinations of the hypophysis before and after intravenous administration of contrast media. Results: The probability for lesion presence showed a trend toward lower scores on standard SE sequences and higher scores with dynamic imaging ( P=0.067). Conclusion: Dynamic keyhole imaging of the pituitary gland could help establish a diagnosis of microadenomas with a higher probability.

Femoral trochlear dysplasia: MR findings.

To establish quantitative and qualitative magnetic resonance (MR) criteria for the diagnosis of trochlear dysplasia. MR images were analyzed in 16 consecutive patients with and 23 without trochlear dysplasia. The standard of reference was a true lateral radiograph of the knee. Quantitative and qualitative MR criteria were assessed. In patients with trochlear dysplasia, the trochlear groove was significantly less deep than that in control subjects. The most accurate measurement was 3 cm above the femorotibial joint space (P: <.001), where a trochlear depth of 3 mm or less had a sensitivity of 100% and a specificity of 96%. The ventral trochlear prominence between the supratrochlear femoral cortex and the most ventral point of the trochlear floor (midsagittal section) was always larger than 6.9 mm in dysplastic trochleae. A facet ratio of less than 2:5 (medial to lateral) 3 cm above joint space level had a sensitivity of 100% and a specificity of 96%. A nipplelike anterior prominence at the superior end of the femoral trochlea on midsagittal images was a specific (91%) qualitative criterion. Dysplasia of the femoral trochlea can be diagnosed reliably by using quantitative or qualitative criteria on midsagittal or transverse MR images obtained 3 cm above the femorotibial joint space.

Symptomatic brachial plexopathy following treatment for breast cancer: utility of MR imaging with surface-coil techniques.

To investigate the clinical utility and diagnostic accuracy of magnetic resonance (MR) imaging in patients with symptomatic brachial plexopathy following treatment for breast cancer. Fifty patients with symptoms of brachial plexopathy (principally pain, weakness, and paresthesia) who had received treatment for breast cancer, which included surgery, radiation therapy, and cytotoxic chemotherapy, underwent MR imaging at 1.5 T. MR imaging was performed by using a body coil, which was supplemented with surface-coil imaging of the cervical spine and shoulder-coil imaging of the brachial plexus. At review, two observers attempted to discriminate between tumor recurrence and nonmalignant causes of symptoms. The diagnosis was verified with histologic analysis or a follow-up of at least 12 months. Of 27 patients demonstrated to have tumor recurrence, 26 were correctly identified by using MR imaging; the recurrence was directly related to the brachial plexus in 17. During the follow-up, 21 patients remained free of recurrence, 20 of whom were determined to have a nonmalignant cause of symptoms. Two of the 50 patients were excluded from the analysis. The MR criteria used for detection of tumor yielded a sensitivity of 96%, specificity of 95%, positive predictive value of 96%, and negative predictive value of 95%. MR imaging is reliable and accurate in the diagnosis of symptomatic brachial plexopathy following breast cancer therapy.

Oral contraceptive use and focal nodular hyperplasia of the liver

Background & Aims: Because most patients with focal nodular hyperplasia (FNH) are young women, an important decision is whether to discontinue oral contraceptive (OC) use. The aims of this study were to evaluate (1) the number and size of FNH lesions in women with various patterns of OC use and in women without OC use and (2) the modifications in the number and size of FNH lesions during follow-up, according to OC use. Methods: In a 9-year study in 216 women with FNH, the diameter and number of lesions documented by magnetic resonance (MR) imaging were evaluated (1) at diagnosis according to OC use as follows: group A, no OC use (n = 28); group B, high-dose OC use (n = 46); group C, low-dose OC use (n = 98); group D, successive use of high-dose and low-dose OCs (n = 33); and group E, use of progestogens only (n = 11); and (2) during follow-up in 136 women, 14 of whom were OC nonusers who stayed off OCs, 89 discontinued OC use, 26 took low-dose OCs, and 7 stayed on a progestogen only. Twelve women became pregnant. In 168 women, the diagnosis of FNH was made based on a combination of rigorously defined MR criteria. In the remaining 48 patients, diagnosis was by surgical biopsy (n = 36) or resection (n = 12). Mean diameter and number of lesion(s) per patient were assessed by MR imaging using the same protocol in all study patients. Results: No significant differences in the number or size of lesions were found in the 5 patient groups. During follow-up, a change in lesion diameter occurred in only 4 women; this event was not influenced by OC use. In the 12 patients who became pregnant, lesion size was unchanged after delivery, pregnancy was uneventful, and delivery occurred spontaneously. Conclusions: These data suggest that (1) neither the size nor the number of FNH lesions are influenced by OC use; (2) size changes during follow-up are rare and do not seem to depend on OC use; and (3) pregnancy is not associated with FNH changes or complications. GASTROENTEROLOGY 2000;118:560-564

Assessment of posterior fossa damage in MS using MRI.

In multiple sclerosis (MS), brain stem and cerebellum are frequent sites of damage in clinically isolated syndromes at presentation and it is likely that lesions located in such structures can have an important impact on the development of disability in the definite forms of the disease. In patients presented with isolated brain stem syndromes, the symptomatic lesion was often not detected by magnetic resonance (MR) imaging. But patients with asymptomatic infratentorial lesions progressed to clinically definite MS in 65% of cases. Infratentorial lesions are included in various MR criteria designed to assist in the differential diagnosis of MS lesions from incidental lesions, to differentiate MS from subcortical encephalopathic arteriopathy. The preferred MR sequence to visualize infratentorial lesions is the fast spin echo sequence. It is preferred to conventional spin echo and fast fluid attenuated inversion recovery sequences because of its relatively short acquisition time and good sensitivity. The correlation between disability and infratentorial lesion load on T2 weighted sequences is controversial. However, it was recently shown that the correlations between clinical measures and T1 lesion load, histogram magnetization transfer ratio and peak positions, and infratentorial volume measurements are strong. These findings suggest that one of the major factors in the development of disability in patients with MS is the pathological damage in clinically eloquent sites such as the brain stem and cerebellum.

Water diffusion in the human hippocampus in epilepsy.

The hippocampus plays a central role in the generation and propagation of seizures in patients with complex partial seizures. Hippocampal sclerosis (HS) is a common structural abnormality in patients with refractory epilepsy. The aim of this study was to quantify diffusion in the hippocampus in patients with epilepsy to evaluate the diffusion changes associated with HS. We scanned 20 subjects (14 patients and 6 controls) with a 1.5T magnetic resonance (MR) system using a cardiac-gated, navigated spin-echo diffusion-weighted sequence. Hippocampal ADC measurements were performed on maps of the ADC measured in three orthogonal directions labeled x, y, and z. The mean ADC (ADCav) and an anisotropy index (AI) were calculated. Hippocampi which fulfilled the MR criteria for HS had a higher ADCav (p < 0.001) and a lower AI (p=0.04) than normal appearing hippocampi in patients and hippocampi in controls. These results imply a loss of structural organization in sclerotic hippocampi and an expansion of the extracellular space. Quantitative measurements of diffusion can be used as an independent parameter for the identification and characterization of abnormal hippocampi in epilepsy.

Avascular necrosis of bone following allogeneic stem cell transplantation: MR screening and therapeutic options.

With improvement in long-term survival after allogeneic stem cell transplantation, late complications with significant morbidity are of increasing importance. We retrospectively analysed 272 recipients of an allogeneic stem cell transplant for the development of osteonecrosis. The incidence among allograft recipients was 6.3% (17/272) for the whole patient population, and 11.8% (17/144) for long-term survivors. All patients were treated with high-dose prednisolone, 16 for severe acute or extensive chronic graft-versus-host disease (GVHD) and one patient for graft rejection. The mean age at time of diagnosis was 33 years (range 16-45) and the mean time from transplant to diagnosis of osteonecrosis was 13 months. Osteonecrosis was diagnosed by magnetic resonance (MR) imaging, which allows early detection of osteonecrosis and assessment of stage. At the time of diagnosis, eight patients had stage I, three patients stage II, three patients stage III and three patients stage IV osteonecrosis according to MR criteria. All but one patient had involvement of the femoral head. The median total dosage of prednisolone at the time of diagnosis was 189 mg/kg (single manifestation 150 mg/kg; multiple manifestations 313 mg/kg) with a total range of 13-555 mg/kg. Six patients were treated by conservative means, 77 patients underwent surgery (three core decompression, eight joint replacement). MR screening of patients receiving high-dose steroids might help to detect osteonecrosis at an early stage and thus prevent progression by early intervention, for example, by core decompression.

Magnetic Resonance Imaging of Epilepsy in Multiple Sclerosis: A Case Control Study. Implications for Treatment Trials with 4-Aminopyridine

A case-control study of epilepsy in multiple sclerosis (MS) is presented using magnetic resonance (MR) imaging to semiquantitatively assess cortical-subcortical lesion load. In this sample of 13 pairs of cases with MS and epilepsy and controls with MS without epilepsy we found statistically higher cumulated cortical-subcortical lesion loads in the cases than in the controls (Wilcoxon, P = 0.036). Total lesion loads (cortical-subcortical plus deep white matter loads) did not differ significantly (P > 0.1) between cases and controls. The relative risk for seizures as determined by the odds ratio of a cortical-subcortical lesion load of > or = 20 was 8.8 (chi 2 = 5.23, P 0.025), the odds ratio of a large (> 1 cm) cortico-subcortical lesion was 4.7 (chi 2 = 4.9, P < 0.05), while the 2 MR criteria combined show an odds ratio of 19.2 (chi 2 = 8.0, P < 0.005). We conclude that: first, the presence of cortical-subcortical lesions in part accounts for the occurrence of seizures in MS patients; second, due to the substantial overlap of MR imaging scores between cases and controls the ultimate use of these MR imaging findings in the management of individual patients or in the organizations of trials should depend on the expected benefit of the treatment. If the benefit is only moderate or not known a cautious approach with exclusion of cases showing a substantial cortical-subcortical lesion load on MR imaging seems appropriate in trials with drugs, like 4-aminopyridine, that lower the epileptic threshold.

Single- and double- lumen silicone breast implant integrity: prospective evaluation of MR and US criteria.

To evaluate the accuracy of magnetic resonance (MR) and ultrasound (US) criteria for breast implant integrity. One hundred twenty-two single-lumen silicone breast implants and 22 bilumen implants were evaluated with surface coil MR imaging and US and surgically removed. MR criteria for implant failure were a collapsed implant shell ("linguine sign"), foci of silicone outside the shell ("noose sign"), and extracapsular gel, US criteria were collapsed shell, low-level echoes within the gel, and "snowstorm" echoes of extracapsular silicone. Among single-lumen implants, MR imaging depicted 39 of 40 ruptures, 14 of 28 with minimal leakage; 49 of 54 intact implants were correctly interpreted. US depicted 26 of 40 ruptured implants, four of 28 with minimal leakage, and 30 of 54 intact implants. Among bilumen implants, MR imaging depicted four of five implants with rupture of both lumina and nine of 10 as intact; US depicted one rupture and helped identify two of 10 as intact. Mammography accurately depicted the status of 29 of 30 bilumen implants with MR imaging correlation. MR imaging depicts implant integrity more accurately than US; neither method reliably depicts minimal leakage with shell collapse. Mammography is useful in screening bilumen implant integrity.

Can MRI predict the histopathological response in patients with osteosarcoma after the first cycle of chemotherapy?

The magnetic resonance (MR) changes after one cycle of chemotherapy were compared with the prechemotherapy studies in 39 patients with osteosarcoma, in order to identify MR changes which can be used to assess early response to chemotherapy. Measurements of total tumour volume, signal intensity, and tumour enhancement of the intra- and extraosseous tumour component were performed. Change in the amount of oedema was subjectively assessed. Changes observed were correlated with histopathological response. Changes in tumour volume and of the signal intensity of the extraosseous tumour component on T2-weighting were the only two parameters which correlated significantly (P < 0.05) with histopathological response. Increase of tumour volume is the most significant parameter and indicates poor response (sensitivity 89%, specificity 73%). Only one good responder showed increase of tumour volume. Decreased or stable tumour volume was observed in both good and poor responders. Increase of signal intensity was found exclusively in five poor responders (sensitivity 100%, specificity 23%). Decreased or stable signal intensity was observed in both good and poor responders. Changes in the amount of oedema and contrast enhancement could not predict response at an early stage. We conclude that increase of tumour volume and increase of T2 signal intensity of extraosseous tumour can be predictive for poor response. MR criteria are not helpful in the early identification of good responders.