Wallerian degeneration of the middle cerebellar peduncle after pontine infarction: MR imaging

PURPOSE: To report magnetic resonance (MR) imaging findings of wallerian degeneration of the pontocerebellar tract secondary to a pontine infarction. MATERIALS AND METHODS: We retrospectively reviewed cranial MR images obtained during the past seven years in our institution and selected those from patients with a chronic stage of pontine infarction and a hyperintense lesion at the central portion of the middle cerebellar peduncle on T2-weighted images. RESULTS: In three patients with a ventromedial pontine infarction, we found a symmetrical hyperintense lesion at the central portion of the middle cerebellar peduncle bilaterally on T2-weighted MR images in the chronic stage. In another patient with a ventrolateral pontine infarction, we found such a lesion at the ipsilateral middle cerebellar peduncle. CONCLUSION: Because the middle cerebellar peduncle carries afferent fibers from the contralateral basis pontis to the cerebellar cortex, these middle cerebellar peduncular lesions are regarded as wallerian degeneration. This secondary degeneration should not be misinterpreted as a newly developed infarction or other disease.     

MR imaging of middle cerebellar peduncle width: differentiation of multiple system atrophy from Parkinson disease

PURPOSE: To prospectively assess if middle cerebellar peduncle (MCP) atrophy, evaluated at magnetic resonance (MR) imaging, can help differentiate multiple system atrophy (MSA) from Parkinson disease (PD). MATERIALS AND METHODS: All participants provided informed consent for participation in the study, which was approved by the institutional review board. Sixteen consecutive patients with MSA, 26 consecutive patients with PD, and 14 healthy control subjects were examined with MR imaging. Images were interpreted independently by two experienced neuroradiologists blinded to clinical information, who visually inspected the images for the presence or absence of putaminal atrophy, putaminal hypointensity, slitlike hyperintensity in the posterolateral margin of the putamen, brainstem atrophy, hyperintensity of the MCP, and cruciform hyperintensity of the pons. Measurements of MCP width on T1-weighted volumetric spoiled gradient-echo images were performed in all subjects. Differences in MCP width among the groups were evaluated by using the Kruskall-Wallis test, followed by the Mann-Whitney U test for multiple comparisons and Bonferroni correction. RESULTS: All patients (mean age, 63.88 years; range, 55-72 years) with MSA had at least one of the features commonly observed in this disease on MR images, whereas control subjects (mean age, 66.93 years; range, 61-77 years) and all but one patient with PD (mean age, 65.31 years; range, 51-79 years) had normal MR images. The average MCP width was significantly smaller in patients with MSA (6.10 mm+/-1.18 [standard deviation]) than in those with PD (9.32 mm+/-0.77, P<.001) or control subjects (9.80 mm+/-0.66, P<.001). CONCLUSION: Measurement of MCP width on MR images may be useful for distinguishing patients with MSA from those with PD.     

MR扩散加权成像鉴别颅内囊性病变的价值

目的探讨MR扩散加权成像（DWI）在颅内囊性病变中的鉴别诊断价值。方法对76例经临床及手术病理证实的颅内囊性病变患者，行常规MR、DWI及增强MR检查，其中脑脓肿19例，原发性脑胶质瘤20例，小脑血管母细胞瘤4例，脑转移瘤10例，蛛网膜囊肿7例，表皮样囊肿16例。回顾性分析颅内囊性病变的DWI信号特征，定量测定囊性变区表观扩散系数（ADC）值。结果DWI上19例脑脓肿呈高信号；34例脑肿瘤患者中，除3例脑胶质瘤呈高信号、1例呈等信号，1例脑转移瘤呈高信号外，其余29例均呈低信号。各种病变ADC值分别为：脑脓肿（0．62±0．15）×10^-3 mm^2／s、脑胶质瘤（2．39±0．78）×10^-3 mm^2／s、脑血管母细胞瘤（2．68±0．40）×10^-3 mm^2／s、脑转移瘤（2．79±0．79）×10^-3 mm^2／s。脑脓肿与脑胶质瘤、脑血管母细胞瘤、脑转移瘤的囊变坏死区ADC值比较，差异均有统计学意义（P〈0．01）；脑胶质瘤与脑血管母细胞瘤、脑转移瘤的囊变坏死区ADC值比较，差异均无统计学意义（P〉0．05）。7例颅内蛛网膜囊肿的DWI呈低信号；16例表皮样囊肿DWI呈明显高信号。颅内蛛网膜囊肿和表皮样囊肿的ADC值分别为（2．96±0．36）×10^-3 mm^2／s和（0．94±0．13）×10^-3 mm^2／s，二者之间差异有统计学意义（P〈0．01）。结论DWI及ADC值对鉴别脑脓肿和囊性或坏死性脑肿瘤具有重要的价值，DWI表现为低信号的颅内囊性病变可除外脑脓肿。     

Adenomyosis and leiomyoma: differential diagnosis with MR imaging

To assess the capability of magnetic resonance (MR) imaging to enable differentiation of adenomyosis from leiomyoma, a prospective study was performed in 21 premenopausal patients with a strong clinical suggestion of adenomyosis. Histologic findings from hysterectomy (19 patients) and biopsy specimens (two patients) showed that eight patients had adenomyosis (three focal, five diffuse) and 12 had leiomyomas (five of the 12 also had microscopic foci of adenomyosis); one patient had a normal uterus. All eight cases of adenomyosis were correctly diagnosed from MR images. On T2-weighted MR images, diffuse adenomyosis appeared as a thickening of the junctional zone, whereas focal adenomyosis appeared as a low-signal-intensity mass poorly marginated from the adjacent myometrium. Ten of the 12 leiomyomas were correctly diagnosed from MR images. In the other two cases of leiomyoma, differentiation between focal adenomyosis and leiomyoma was not possible. Microscopic foci of adenomyosis were not demonstrated with MR imaging.     

Decreased signal intensity of the middle cerebellar peduncle on diffusion-weighted MRI in patients with large supratentorial lesions

PURPOSE: The purpose of this work was to evaluate signal intensity change of the middle cerebellar peduncles on diffusion-weighted imaging in patients with large supratentorial lesions. METHODS: Signal intensity of the middle cerebellar peduncles was measured using a region of interest in 40 normal control subjects and in 28 patients with moyamoya disease on axial diffusion-weighted imaging with the motion-probing gradient perpendicular to the image. An additional six patients without moyamoya but with large supratentorial sequelae of hemorrhage or infarction were also included. RESULTS: There was no difference in signal intensity between both middle cerebellar peduncles in normal subjects, but lower signal intensity was consistently observed in the contralateral middle cerebellar peduncle in 12 moyamoya patients with large supratentorial lesions in the middle cerebral artery distribution. This finding was observed in the six non-moyamoya patients, too. CONCLUSION: Decreased signal intensity of the contralateral middle cerebellar peduncle might be a remote effect caused by a large supratentorial lesion in a crossed cerebellar fashion.     

Congenital chest lesions: diagnosis and characterization with prenatal MR imaging.

PURPOSE: To evaluate prenatal magnetic resonance (MR) imaging for diagnosis of fetal chest masses and to determine if MR imaging provides information in addition to that of ultrasonography (US). MATERIALS AND METHODS: Eighteen pregnant women were referred for MR imaging of possible fetal chest tumors seen at US (16 congenital cystic adenomatoid malformation [CCAM], two bronchopulmonary sequestration [BPS]). The presence, position, size, and characteristics of masses were determined and correlated with postnatal results. RESULTS: The MR imaging diagnoses were three cases of congenital diaphragmatic hernia, nine of CCAM, two of BPS, and one each of foregut cyst, lung atresia, tracheal atresia, and bronchial stenosis. MR imaging results were in agreement with US results in nine fetuses and in disagreement in nine. MR imaging diagnoses were confirmed at surgery or autopsy in 17 fetuses. MR imaging results led to an error in diagnosis in one fetus with BPS. CONCLUSION: Fetal chest masses had characteristic MR imaging appearances. MR imaging was accurate for distinguishing congenital diaphragmatic hernia from CCAM and was useful for less common diagnoses and determination of the origin of very large chest tumors. Prenatal diagnosis was changed in some patients owing to MR results and affected treatment and counseling of parents. MR imaging is a valuable adjunct to US for prenatal diagnosis of fetal chest masses.     

小脑髓母细胞瘤的MRI影像特征及鉴别诊断

目的:探讨小脑髓母细胞瘤的MRI表现及鉴别诊断。方法:回顾性分析21例经手术病理证实的小脑髓母细胞瘤的MRI资料,所有病例均行MRI平扫及增强扫描,5例行FLAIR序列及弥散加权成像(DWI)。结果:21例髓母细胞瘤中,19例位于小脑蚓部(占90%),2例位于小脑半球(占10%)。发病年龄5～41岁,15岁以下11例(占52%)。肿瘤平均大小约33mm,18例病灶边界较清楚,3例病灶周边模糊。圆形或类圆形11例,不规则形3例,边缘分叶5例。16例病灶内可见囊变、坏死。MRI扫描,T1WI呈稍低、等信号,T2WI呈等、稍高信号,FLAIR序列呈等、稍高信号,DWI序列病灶实性成分呈高信号,表面扩散系数(ADC)图呈略低信号。增强扫描大部分病灶不同程度强化。12例病灶周边见不规则水肿。结论:小脑髓母细胞瘤具有典型好发部位及特征性MRI影像表现,早期诊断有助于临床治疗及提高患者生存质量。     

Cystic focal liver lesions in the adult: differential CT and MR imaging features.

Cystic lesions of the liver in the adult can be classified as developmental, neoplastic, inflammatory, or miscellaneous. Although in some cases it is difficult to distinguish these entities with imaging criteria alone, certain cystic focal liver lesions have classic computed tomographic (CT) and magnetic resonance (MR) imaging features, which are important for the radiologist to understand and recognize. Lesions with such features include simple (bile duct) cyst, autosomal dominant polycystic liver disease, biliary hamartoma, Caroli disease, undifferentiated (embryonal) sarcoma, biliary cystadenoma and cystadenocarcinoma, cystic subtypes of primary liver neoplasms, cystic metastases, pyogenic and amebic abscesses, intrahepatic hydatid cyst, extrapancreatic pseudocyst, and intrahepatic hematoma and biloma. Specific CT and MR imaging findings that are important to recognize are the size of the lesion; the presence and thickness of a wall; the presence of septa, calcifications, or internal nodules; the enhancement pattern; the MR cholangiographic appearance; and the signal intensity spectrum. In addition, access to critical clinical information remains extremely important. The most important clinical parameters defined include age and gender, clinical history, and symptoms. An understanding of the classic CT and MR imaging appearances of cystic focal liver lesions will allow more definitive diagnosis and shorten the diagnostic work-up.     

Forefoot pain involving the metatarsal region: differential diagnosis with MR imaging.

Many disorders produce discomfort in the metatarsal region of the forefoot. These disorders include traumatic lesions of the soft tissues and bones (eg, turf toe, plantar plate disruption, sesamoiditis, stress fracture, stress response), Freiberg infraction, infection, arthritis, tendon disorders (eg, tendinosis, tenosynovitis, tendon rupture), nonneoplastic soft-tissue masses (eg, ganglia, bursitis, granuloma, Morton neuroma), and, less frequently, soft-tissue and bone neoplasms. Prior to the advent of magnetic resonance (MR) imaging, many of these disorders were not diagnosed noninvasively, and radiologic involvement in the evaluation of affected patients was limited. However, MR imaging has proved useful in detecting the numerous soft-tissue and early bone and joint processes that occur in this portion of the foot but are not depicted or as well characterized with other imaging modalities. Frequently, MR imaging allows a specific diagnosis based on the location, signal intensity characteristics, and morphologic features of the abnormality. Consequently, MR imaging is increasingly being used to evaluate patients with forefoot complaints. Radiologists should be familiar with the differential diagnosis and MR imaging features of disorders that can produce discomfort in this region.     

Adhesive capsulitis: role of MR imaging in differential diagnosis

The purpose of this study was to describe and characterize the MR imaging findings in a group of patients who underwent surgery for adhesive capsulitis. Twenty-four MR imaging studies in 24 consecutive patients with clinical evidence of adhesive capsulitis were performed prior to arthroscopic capsulotomy. There were 17 women and 7 men with a mean age of 53.5 years. Images were scrutinised for changes in the synovium particularly in the rotator interval, around the biceps anchor and axillary pouch. Intravenous gadolinium was given routinely. We also examined a control group of 22 patients who underwent the same MR imaging protocol after referral for rotator cuff pathology. Soft tissue density showing variable enhancement after gadolinium administration was visible in the rotator interval in 22 of 24 studies on MR imaging. Seventeen patients showed soft tissue density partially encasing the biceps anchor. Ten patients showed thickening and gadolinium enhancement of the axillary pouch. Three patients from the study cohort had partial tears of the supraspinatus tendon. All the patients subsequently had surgery which confirmed fibrovascular scar tissue in the rotator interval, around the biceps anchor and a variable degree of synovial inflammation of the glenohumeral capsule. Two patients from a control group with suspected rotator cuff pathology showed abnormal intensity in the rotator interval on MR imaging. Magnetic resonance imaging can identify changes in the shoulder joint that correspond to abnormalities seen at surgery. This may be useful for discriminating adhesive capsulitis from other causes of shoulder pain.     

胰头癌的MRI诊断及鉴别诊断

目的：探讨磁共振成像对胰头癌的诊断价值。方法：回顾性分析28例经手术病理及其它方法证实的胰头痛变的MRI表现。扫描序列包括SE序列T1WI、FSE序列T2WI、T1WI FS、T2WI FS、25例行MRCP,12例行增强扫描。结果：26例MRI诊断为胰头癌,23例诊断正确。2例为胰头炎性病变误诊为胰头癌。23例胰头癌T1WI、T2WI肿瘤信号呈多样性,T1WI FS肿瘤组织低于正常胰腺组织,MRCP呈“双管征”,胆总管下端呈截断征象。结论：应用MRI多序列成像结合MRCP、能够对胰头癌进行准确定位,并有较高的定性价值。     

女性盆腔良性占位性病变的MRI诊断与鉴别诊断

目的 评价MRI对女性盆腔良性占位病变的诊断价值.方法 回顾性分析33例经手术病理证实的盆腔良性占位病变患者的MRI征象.结果 33例手术病理检出64个病灶,MRI检出59个(59/64,92.2%),3个子宫肌瘤及2个成熟畸胎瘤MRI未检出而漏诊(5/64,7.8%).MRI检出的59个病灶中57个病灶部位与手术病理一致,准确性为96.6%(57/59),56个病灶MRI诊断结果与手术病理相符,符合率94.9%(56/59).子宫病变主要表现为实质性肿块或子宫内膜增厚;卵巢病变主要表现为囊性、囊实性肿块影.结论 MRI对盆腔良性肿块的定位具有很高的准确性,对良性肿块的鉴别诊断亦具有较高的准确性.     

Decreased fractional anisotropy of middle cerebellar peduncle in crossed cerebellar diaschisis: diffusion-tensor imaging-positron-emission tomography correlation study

BACKGROUND AND PURPOSE: The purpose of this study was to evaluate the clinical usefulness of diffusion tensor MR imaging (DTI) for the assessment of chronic stroke with crossed cerebellar diaschisis (CCD). METHODS: Twenty-two patients (15 men and 7 women; mean age, 60 years) with chronic stroke (13 ischemic and 9 hemorrhagic) were evaluated by diffusion-tensor MR imaging (DTI) and (18)F-fluorodeoxyglucose (FDG)-positron-emission tomography (PET). Fractional anisotropy (FA) and color-coded vector maps were generated. To evaluate afferent fiber systems to the cerebellum, the FA of the bilateral middle cerebellar peduncle (MCP) was measured. Changes of FA values in the MCP were compared against PET results. RESULTS: In patients with a chronic infarct involving more than one-third of the unilateral hemisphere, MCP of the contralesional side showed an FA value of 0.5226 +/- 0.0174, which was significantly lower than that of the ipsilesional side MCP (0.5366 +/- 0.0159) (one-tail paired t test, P = .0009). On FDG-PET scan, decreased glucose metabolism was observed in the affected cerebellum in 19 patients (86.4%). CONCLUSION: DTI can visualize an altered corticocerebellar circuit in the case of chronic stroke with CCD, which is hardly demonstrated by conventional MR images.     

Benign and malignant breast lesions: diagnosis with multiparametric MR imaging

PURPOSE: To both develop and use a tissue signature method for the identification and classification of breast lesions and healthy breast tissue with magnetic resonance (MR) imaging. MATERIALS AND METHODS: Thirty-six patients underwent breast MR imaging (T1- and T2-weighted imaging and three-dimensional T1-weighted imaging with and without contrast material enhancement), followed by biopsy or mastectomy and histopathologic analysis. Tissue cluster analysis was performed by using the iterative self-organizing data technique to identify glandular, adipose, and lesion tissue signature vectors. Glandular and lesion tissue vectors were characterized by angular separation from the reference adipose tissue vector. Differences in angular separation of histologically proved benign and malignant lesion groups were evaluated with an independent t test. The usefulness of the angular separation model for distinguishing benign from malignant lesions was evaluated with nonparametric receiver operating characteristic curve analysis. RESULTS: The model enabled successful identification and characterization of breast lesion tissue clusters in all patients; 18 lesions were benign, and 18 were malignant. Angular separation +/- SD was 17.8 degrees +/- 6.1 degrees between adipose tissue and malignant lesions and 29.0 degrees +/- 11.2 degrees between adipose tissue and benign lesions. Angular separations of benign lesions and malignant lesions were significantly different (P =.002), with a specificity of 78% and sensitivity of 89% at a cutoff value of 21 degrees. Significant differences in angular separation from adipose tissue also were found between glandular tissue and lesion tissue (P <.001) and, in glandular tissue, between patients with benign lesions and those with malignant lesions (P =.04). The area under the receiver operating characteristic curve was 0.84. CONCLUSION: Multispectral analysis of conventional breast MR images based on the iterative self-organizing data model and on measurement of angular separation between tissue signature vectors may enable automated lesion identification and classification.     

MR imaging in the differential diagnosis of scrotal and testicular disease

It is frequently impossible to discriminate between various causes of scrotal pain and swelling by means of clinical examination and ultrasound (US) alone. Surgical exploration is necessary in cases of indefinite differential diagnosis. For evaluation of the diagnostic potential of magnetic resonance (MR) imaging in scrotal disease, 200 patients with testicular abnormalities were studied. For 74 of these patients, the diagnosis was cancer, based on clinical and US findings. MR imaging demonstrated malignant disease in 54 patients and benign disease in 20. All of the MR imaging findings were confirmed at surgical biopsy. Despite high costs of the procedure, the authors believe that MR imaging is a useful aid for diagnosis in cases of indefinite findings in scrotal and testicular disease.     

MR imaging in the differential diagnosis of neurogenic foot drop

BACKGROUND AND PURPOSE: Prolonged T2 relaxation time of denervated muscle has been described in several clinical and experimental studies. The purpose of this study was to evaluate the utility of MR imaging in the diagnosis of neurogenic muscle disorders compared with that of clinical and electrophysiologic examination. METHODS: In a prospective study, 40 consecutive patients clinically presenting with a foot drop were included. MR imaging of the lower leg included axial T1-weighted and axial turbo inversion recovery magnitude (TIRM) sequences. Two readers blinded to clinical data evaluated T1-weighted images for anatomic localization of affected muscles and TIRM images for patterns of signal intensity increase. After MR imaging, a detailed neurophysiologic examination was performed. Cause of foot drop was independently determined on the basis of MR and electrophysiologic data. RESULTS: Clinical examination and electromyography (EMG) disclosed 20 peroneal nerve lesions, nine cases of L5 radiculopathy, and 11 nerve lesions extending beyond neural structures. MR imaging revealed three distinct patterns of signal intensity increase on TIRM images: peroneal nerve pattern, L5 pattern, and unspecific pattern. MR imaging and EMG findings were in agreement in 37 (92%) of 40 patients. In three patients, MR imaging revealed a more widespread involvement than did EMG. In one of these patients, denervation in the corresponding muscle was validated by follow-up EMG. No false-negative diagnoses were made by use of MR imaging as compared with use of EMG. CONCLUSION: MR imaging improves accuracy in the differential diagnosis of peripheral nerve lesions compared with that of EMG and can supplement EMG in the diagnosis of denervated muscles.