Diffusion tensor MR imaging in pediatric head trauma

PURPOSE: We propose to investigate the fractional anisotropy (FA) values in pediatric patients with closed head trauma and correlate them with the initial Glasgow Coma Scale (GCS). MATERIALS AND METHODS: A retrospective evaluation of 24 pediatric patients (15 men, 9 women; mean age, 13 years; range, 2-18 years) who underwent both unenhanced head computed tomography and cerebral magnetic resonance imaging (MRI), including the tensor diffusion sequence, within 30 days of the incident. Twenty-two atraumatic control patients (9 men, 13 women; mean age, 9 years; range, 4-17 years) were randomly selected from the records of the radiology department within the same period. Fractional anisotropy measurements were taken from each of 6 major white matter volumes. Data extracted from the record of each subject included GCS, initial head computed tomographic results, and length of hospital stay. Kruskal-Wallis and t tests were used for statistical evaluation. RESULTS: The mean acute score on the GCS was 9.7 +/- 5. Mean duration of hospitalization days was 8.7 +/- 10. Statistically significant differences in mean FA values between trauma and control subjects were noted in corpus callosum. Trauma patients with positive findings on MRI and with GCS less than 10 also had lower FA values than patients with GCS greater than 10 and patients who had normal MRI findings. There was a negative correlation between time to discharge and FA values. CONCLUSIONS: In pediatric head trauma, MRI diffusion FA measurements can show abnormalities despite normal-appearing brain MRI findings. Larger investigations are required to verify the stability of correlations.     

MR imaging features of nongynaecologic cystic lesions of the pelvis

ObjectiveThe purpose of our article is to review the magnetic resonance imaging (MRI) features of nongynaecologic cystic lesions of the pelvis.ConclusionThe rising use of MRI for pelvic exploration will result in an increase in incidental detection of pelvic cystic cysts. Pelvic cysts of non gynecologic origin are less frequent than gynecologic cysts. However, they account for a wide range of abnormalities, and radiologists must be aware of their features and characteristics     

Extracranial lesions of the head and neck: preliminary experience with Gd-DTPA-enhanced MR imaging

The authors report initial experience with magnetic resonance imaging enhanced with gadolinium diethylenetriaminepentaacetic acid (DTPA) in 27 patients with various extracranial lesions of the head and neck. Unenhanced T1- and T2-weighted images were compared with T1-weighted images obtained 3-30 minutes after Gd-DTPA administration. Overall, compared with precontrast T1- and T2-weighted images, Gd-DTPA improved the visibility of lesions in 11 and five of 27 patients, respectively. Gd-DTPA particularly improved the conspicuity of tumors of the nasal cavity and paranasal sinuses and tumors having perineural or intracranial extension. Gd-DTPA-enhanced images were equivalent to precontrast T1- and T2-weighted images in five and 13 patients, respectively, and inferior to them in nine and eight patients, respectively. Mixed results were obtained in two patients and one patient when Gd-DTPA-enhanced images were compared with T1- and T2-weighted images, respectively. The authors conclude that Gd-DTPA has definite but limited uses in extracranial head and neck pathologic conditions and that more research is needed to evaluate particular applications.     

Breast lesions detected on MR imaging: features and positive predictive value

OBJECTIVE: The purpose of this study was to analyze features of breast lesions detected on MR imaging that had subsequent biopsy and to determine the positive predictive value (PPV) of these features. MATERIALS AND METHODS: Retrospective review was performed of 100 consecutive solitary MR imaging-detected breast lesions that had MR imaging-guided needle localization and surgical excision. We described lesions, using terms found in a proposed breast MR imaging lexicon. Histologic findings were reviewed. RESULTS: Carcinoma was identified in 25 lesions (25%), including ductal carcinoma in situ (DCIS) in 13 (52%) and infiltrating carcinoma in 12 (48%). Carcinoma was found in 15 (25%) of 60 masses versus 10 (25%) of 40 nonmass lesions; most malignant masses (73%) were infiltrating carcinoma, whereas most malignant nonmass lesions (90%) were DCIS. The features with the highest PPV were spiculated margin (80% carcinoma), rim enhancement (40% carcinoma), and irregular shape (32% carcinoma) for mass lesions and segmental (67% carcinoma) or clumped linear and ductal enhancement (31% carcinoma) for nonmass lesions. Visually assessed kinetic patterns were not significant predictors of carcinoma, but washout was present in 70% of infiltrating carcinomas versus 9% of DCIS lesions (p < 0.01). Carcinoma was present in 17 (19%) of 88 lesions classified as suspicious versus eight (67%) of 12 lesions classified as highly suggestive of malignancy (p = 0.001). CONCLUSION: Among MR imaging-detected breast lesions referred for biopsy, carcinoma was found in 25%, of which half were DCIS. Features with the highest PPV were spiculated margin, rim enhancement, and irregular shape for mass lesions and segmental or clumped linear and ductal enhancement for nonmass lesions. Final assessment categories were significant predictors of carcinoma.     

CT and MR imaging of primary cerebrovascular complications in pediatric head trauma

The incidence of severe traumatic head injury in children has constantly increased over the last years. Diagnostic imaging has become an unrenounceable tool for the documentation and follow-up of intracranial lesions. The use of magnetic resonance imaging (MRI) in the early posttraumatic phase has led to a more thorough understanding of intracranial injuries. We retrospectively analyzed the cranial computed tomography (CCT) and magnetic resonance (MR)-studies of patients with traumatic head injuries for primary cerebrovascular complications. In 64 children (45 male, 19 female) with traumatic head injuries, CCT and MR examinations were available for analysis. The children's age ranged from 3 months to 15 years with a median age of 7 years. All patients had initial CCT on admission to the hospital with follow-up examinations depending on clinical state and initial imaging findings. All patients had at least one MR examination between 0 to 120 days after the trauma with a median time interval of 17 days. In five of 64 (7.8%) patients, cerebrovascular complications were found on imaging studies. Initial imaging within the first 24 h after the trauma detected a complete middle cerebral artery infarction in one patient and extensive sinus thrombosis after a complex skull fracture in another. In two patients, thrombosis of the transverse sinus appeared on MRI 4 to 6 days after the trauma. In another patient with open-skull injury, a posttraumatic aneurysm of the pericallosal artery was diagnosed on MRI 30 days after the trauma. Our study shows that, although primary cerebrovascular lesions after traumatic head injuries in children are rare, the radiologist should be aware of the characteristic injury patterns and the time appearance of imaging findings on CT and MRI.     

Delayed encephalopathy after acute carbon monoxide intoxication: MR imaging features and distribution of cerebral white matter lesions.

Magnetic resonance (MR) images obtained in 15 patients with delayed encephalopathy after acute carbon monoxide (CO) intoxication were reviewed. Images had been obtained 4-9 weeks after exposure to CO, during the relapse of neuropsychiatric symptoms after initial recovery. Bilateral symmetric confluent high signal intensity in the periventricular white matter and centrum semiovale was seen on long-repetition-time images (n = 15). The high intensity extended into the corpus callosum (n = 11), subcortical U fibers (n = 12), and external (n = 9) and internal (n = 7) capsules. Bilateral diffuse low-intensity signal in the thalamus and putamen on T2-weighted images, suggesting iron deposition, was demonstrated in 10 patients. Bilateral ischemia or necrosis of the globus pallidus was seen in nine patients. In three of four patients with follow-up MR imaging studies, a decrease in extent and signal intensity of white matter lesions accompanied lessening of clinical symptoms. These results suggest that the main pathologic feature of delayed encephalopathy associated with CO intoxication is a reversible demyelinating process of the cerebral white matter.     

3D MR imaging with Gd-DTPA in head and neck lesions

Three-dimensional MR imaging technique is not a new concept, however, there is very little experience concerning clinical trials. Especially in head and neck lesions, the accuracu of this new imaging method has not yet been tested. A pilot study was performed to evaluate the diagnostic value of demonstrating the head and neck lesions and topographical structures implemented in a three-dimensional reconstruction of the entire head. The 3D reconstruction mode is based on the ray-tracting model. The application of the contrast medium Gd-DTPA proved to be helpful. Three-dimensional reconstruction revealed clear topographic details of the lesions, including the spread of infiltration and destruction of soft tissue. Additionally, the simultaneous view of multiple slices in different orientations is an ideal method for evalauting the spread of the lesion and to visualize the relation between lesion and surrounding tissue. Offprint request to: T. Vogl     

Multishot diffusion-weighted MR imaging features in acute trauma of spinal cord

Objectives

To analyse diffusion-weighted MRI of acute spinal cord trauma and evaluate its diagnostic value.

Methods

Conventional MRI and multishot, navigator-corrected DWI were performed in 20 patients with acute spinal cord trauma using 1.5-T MR within 72 h after the onset of trauma.

Results

Twenty cases were classified into four categories according to the characteristics of DWI: (1) Oedema type: ten cases presented with variable hyperintense areas within the spinal cord. There were significant differences in the apparent diffusion coefficients (ADCs) between lesions and unaffected regions (t?=?-7.621, P?<?0.01). ADC values of lesions were markedly lower than those of normal areas. (2) Mixed type: six cases showed heterogeneously hyperintense areas due to a mixture of haemorrhage and oedema. (3) Haemorrhage type: two cases showed lesions as marked hypointensity due to intramedullary haemorrhage. (4) Compressed type (by epidural haemorrhage): one of the two cases showed an area of mild hyperintensity in the markedly compressed cord due to epidural haematoma.

Conclusions

Muti-shot DWI of the spinal cord can help visualise and evaluate the injured spinal cord in the early stage, especially in distinguishing the cytotoxic oedema from vasogenic oedema. It can assist in detecting intramedullary haemorrhage and may have a potential role in the evaluation of compressed spinal cord.

Key Points

? Multishot, navigator-corrected diffusion-weighted MRI is helpful when evaluating spinal cord injury (SCI). ? Four types of SCI may be classified according to the DWI characteristics. ? DWI differentiates cytotoxic from vasogenic oedema, thereby determining the centre of SCI. ? DWI can assist in detecting intramedullary haemorrhage. ? DWI can help evaluate the degree of compressed spinal cord.     

Synovial recesses of the knee: MR imaging review of anatomical and pathological features

The knee joint is a complex anatomical structure playing host to a wide variety of pathological processes. Knowledge of the anatomy of the synovial recesses and plicae relating to the knee is important, as the appearance of pathology in these unusual locations may, even for commonly encountered conditions, lead to diagnostic uncertainty. This review article discusses the magnetic resonance imaging (MRI) anatomy of the knee joint with an emphasis on the synovial recesses and plicae. The MRI appearance of a variety of synovial and osteochondral diseases that may involve these sites is illustrated.     

头颈部病变MR扩散成像的初步研究

目的探讨MR扩散加权成像（DWI）在头颈部病变中的诊断价值。方法回顾性分析57例头颈部病变共85个病灶，其中恶性肿瘤22个（22例），良性肿瘤13个（13例），囊性或液性病灶13例共17个病灶，包括囊肿12个（8例），肿瘤坏死4个（4例），脓肿1个（1例）；淋巴结病灶33个。所有患者均经临床追踪或手术病理证实。分析各病灶在扩散敏感因子（b值）为0、500和1000s·mm^-2时DWI特点及其表观扩散系数（ADC）值。结果良、恶性肿瘤在DWI表现有所不同，13个良性肿瘤与脊髓（或脑干）的信号比值随b值增加迅速下降；22个恶性肿瘤与脊髓（或脑干）信号比值随b值增加变化不明显。恶性肿瘤的平均ADC值[（0．78±0．24）×10^-3mm^2·s^-1]低于良性肿瘤[（1．48±0．20）×10^-3mm^2·s^-1]，差异有统计学意义（t=8．9，P〈0．01）；良、恶性肿瘤的ADC值受试者特异性曲线（ROC）下面积Az值为0．971±0．030，当ADC值取1.13×10^-3mm^2·s^-1时，判断良、恶性肿瘤的敏感度为100％，特异度为90．5％，准确度90．5％。鳞状细胞癌的ADC值与分化程度相关，分化好者其ADC值高。囊性或液性病变（12个）、肿瘤坏死（4个）和脓肿（1个）在DWI上的信号强度与其组织病理成分相关，具有一定的信号特征和ADC值。淋巴结转移瘤的平均ADC值[（0．81±0．11）×10^-3mm^2·s^-1]高于良性淋巴结病变[（0．69±0．04）×10^-3mm^2·s^-1]，差异有统计学意义（t=3．48，P〈0．01），但是两者之间有较大的重叠，且在DWI上表现相仿。结论DWI和ADC值在头颈部病变的鉴别诊断中具有重要价值。     

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.     

MR imaging of trauma: elbow and wrist

The use of magnetic resonance imaging (MRI) in the setting of acute trauma is increasing due to many factors including availability and demand. The ability to evaluate for occult fractures in addition to concomitant soft tissue injuries has a significant impact on patient management and MRI is the ideal adjunct to plain radiography. Occult fractures in the forearm, particularly the radial head and scaphoid, are common and often lead to repeated examinations and delayed diagnosis, which can be avoided by the use of MRI early in patient investigation. Orthopedists are increasingly performing ligament repairs at the time of fracture fixation and therefore benefit from preoperative MRI to assess the extent of soft tissue injury.     

Follow-up of occult bone lesions detected at MR imaging: systematic review

PURPOSE: To perform a systematic review of the literature regarding the natural course of posttraumatic occult bone lesions (often referred to as bone bruises) detected at magnetic resonance (MR) imaging. MATERIALS AND METHODS: A systematic review of the literature was performed by searching the MEDLINE database (from January 1966 to February 2003) with the keywords bone bruise, trauma, follow-up, and MRI. Keywords were linked by using the Boolean operator AND. Studies were included if all of the following criteria were fulfilled: patients sustained trauma, MR imaging was used as a diagnostic method, results of clinical or MR imaging follow-up were available, and study was written in English, Dutch, German, French, Spanish, Italian, Swedish, Danish, or Norwegian. The quality of each study was assessed by using a standardized criteria set, and kappa statistics were estimated to rate the level of agreement between the two reviewers. Results were compared with regard to study design and quality scores. RESULTS: The MEDLINE search identified 266 articles, 13 of which met the inclusion criteria. The quality of the included studies was moderate. The two reviewers initially agreed on 179 quality items (kappa = 0.84). The study population was generally small, and follow-up periods ranged from 1 to 73 months. Four different classification systems were used, and in two studies bone bruise was not specified. Study results suggest a generally good clinical prognosis of bone bruises. Normalization of MR imaging appearance is possible and is most often encountered after the occurrence of reticular lesions. Cartilage loss at follow-up is often found in cases of initial cartilage damage (impaction or osteochondral fracture). CONCLUSION: In general, a healing response was often encountered after sustained posttraumatic occult bone lesions. The initial MR imaging appearance appears to have prognostic value.     

Lacrimal gland tumors and simulating lesions. Clinicopathologic and MR imaging features

The lacrimal gland region can be involved in a wide spectrum of orbital pathology, including inflammatory, lymphoproliferative, and epithelial tumors. This article focuses on benign and malignant epithelial tumors of lacrimal gland and simulating lesions. The clinical presentations, MR imaging, and pathologic findings of lacrimal gland tumors are reviewed.     

Leukodystrophy in children: a pictorial review of MR imaging features.

Dysmyelinating diseases, or leukodystrophies, encompass a wide spectrum of inherited neurodegenerative disorders affecting the integrity of myelin in the brain and peripheral nerves. Most of these disorders fall into one of three categories-lysosomal storage diseases, peroxisomal disorders, and diseases caused by mitochondrial dysfunction-and each leukodystrophy has distinctive clinical, biochemical, pathologic, and radiologic features. Magnetic resonance (MR) imaging has become the primary imaging modality in patients with leukodystrophy and plays an important role in the identification, localization, and characterization of underlying white matter abnormalities in affected patients. MR imaging has also been extensively used to monitor the natural progression of various white matter disorders and the response to therapy. Although the MR imaging features of leukodystrophy are often nonspecific, systematic analysis of the finer details of disease involvement may permit a narrower differential diagnosis, which the clinician can then further refine with knowledge of patient history, clinical testing, and metabolic analysis.     

MR imaging of the head and neck

The purpose of this paper is to describe current imaging protocols for MR imaging of the head and neck region and to define results and clinical impact. Depending on the clinical question, different MRI protocols are presented for imaging of the head and neck. The appearance of different pathologic findings on imaging studies and how adapted imaging protocols help to improve differential diagnosis is discussed. In summary, MRI is the method of choice for imaging of the head and neck.     

Brain radiation lesions: MR imaging

This retrospective study was performed to assess the capability of magnetic resonance (MR) to depict and characterize diffuse and focal radiation lesions in the brain using the spin-echo technique. The MR images of 55 patients who had undergone radiation therapy were reviewed. Comparative computed tomography (CT) studies were available for all the patients. Normal white matter was chosen as reference tissue for the quantitative comparison of signal intensities. Radiation lesions (identified in eight patients) were seen as regions of high signal intensity on the sequence with a long repetition time (TR) (2.0 sec) and showed no difference in signal compared with white matter when the TR was short (0.5 sec). Nonspecific prolongation of T1 and T2 relaxation times was measured in such lesions. In one patient, subependymal tumor spread, demonstrated by contrast-enhanced CT, was missed on MR images, masked by the adjacent abnormal signal owing to radiation effects. Recurrent or residual brain tumor could not be distinguished from radiation brain necrosis either by CT or by MR imaging. It is concluded that MR can depict radiation lesions with great sensitivity but is not very helpful for discrimination between recurrent or residual brain tumor, radiation necrosis, and other brain lesions.     

MR imaging of spinal trauma

Magnetic resonance (MR) imaging plays an increasingly important role in evaluation of the patient who has sustained spinal trauma. This review discusses the role of MR imaging relative to plain radiographs and computed tomography in the evaluation of the patient with spinal trauma and presents a method for systematic review of MR images for assessing spinal injury.