Fast MR imaging in obstetrics.

Ultrasonography (US) is the initial imaging modality of choice for evaluation of patients in obstetrics. However, the results of US are not always sufficient. Magnetic resonance (MR) imaging, which uses no ionizing radiation, may be an ideal method for further evaluation. Although MR imaging is not recommended during the first trimester and use of contrast material is not recommended in pregnant patients, fast MR imaging is useful in various obstetric settings and can provide more specific information with excellent tissue contrast and multiplanar views. In pregnant patients with acute conditions, various diseases (eg, red degeneration of a uterine leiomyoma) may be diagnosed. MR imaging allows characterization of pelvic masses discovered during pregnancy and diagnosis of postpartum complications (eg, abscess, hematoma, ovarian vein thrombosis). In pregnant patients with hydronephrosis, MR urography can demonstrate the site of obstruction and the cause (eg, a ureteral stone). MR pelvimetry may be beneficial in cases of breech presentation. Contrast material-enhanced dynamic MR imaging allows one to evaluate the vascularity of a placental polyp, detect the viable component of a gestational trophoblastic tumor, and diagnose a uterine arteriovenous malformation. MR imaging enables diagnosis of rare forms of ectopic pregnancy and early diagnosis of ectopic pregnancy.     

Duodenal diverticula mimicking cystic neoplasms of the pancreas: CT and MR imaging findings in seven patients

OBJECTIVE: Duodenal diverticula are common and are typically asymptomatic. When filled with gas or a combination of fluid and gas, duodenal diverticula are easily recognized on CT or MR imaging. However, a duodenal diverticulum that is entirely filled with fluid may mimic a cystic neoplasm arising from the head of the pancreas. We present seven cases of patients with duodenal diverticula in whom initial findings on CT or MR imaging were suggestive of a cystic neoplasm in the head of the pancreas. In all patients, this structure was ultimately proven to be a duodenal diverticula. CONCLUSION: When filled with only fluid, a duodenal diverticulum may mimic a cystic neoplasm in the head of the pancreas. Recognizing the location in which this entity characteristically arises and identifying small amounts of intradiverticular gas when it is present may aid in establishing the correct diagnosis in patients with duodenal diverticula.     

Groove pancreatic carcinomas: radiological and pathological findings

The aim of this study was to clarify the characteristics of pancreatic head carcinomas mainly invading the groove between the duodenum and the pancreatic head. Nine patients with pathologically proven pancreatic head carcinomas underwent thin-slice dynamic CT, MR imaging, duodenal endoscopy, and angiography (seven patients). Plate-like masses within the groove region were seen in all cases, which showed hypointensity on T1-weighted images and slight hyperintensity on T2-weighted MR images. The masses appeared hypovascular in the early phase and delayed enhancement in the late phase of dynamic CT and MR imaging. On MR cholangiopancreatography, stenosis of intrapancreatic common bile duct was seen in all patients, whereas stenosis of the main pancreatic duct was seen in only three cases. Endoscopy revealed luminal narrowing of the duodenum in all patients, and duodenal mucosal biopsy demonstrated adenocarcinoma in seven patients. Abdominal arteriography showed serrated encasement of peripancreatic arteries in seven patients who received angiographic examinations. The CT and MR imaging findings of groove pancreatic carcinomas resemble those of groove pancreatitis. Differential diagnosis may be achieved by the pathological diagnosis of a biopsy specimen of the duodenal mucosa and arterial encasement on arteriography.     

Spinal epidural hemangiomas: various types of MR imaging features with histopathologic correlation

BACKGROUND AND PURPOSE: Because of the high vascularization of hemangiomas, preoperative misinterpretation may result in unexpected intraoperative hemorrhage and incomplete resection, which results in the persistence of clinical symptoms or recurrence. Our purpose was to analyze various MR imaging features of a spinal epidural hemangioma with histopathologic correlation. MATERIALS AND METHODS: After searching through the pathology data bases in 3 hospitals, we included 14 patients (9 male and 5 female; mean age, 38 years; age range, 2-62 years) with spinal epidural hemangiomas confirmed by surgical resection after MR imaging. Three radiologists reviewed the MR imaging in consensus and categorized the features into subtypes on the basis of histopathologic findings. RESULTS: We categorized the MR imaging features as follows: type A for a cystlike mass with T1 hyperintensity (2 cases, arteriovenous type with an organized hematoma), type B for a cystlike mass with T1 isointensity (3 cases, venous type), type C for a solid hypervascular mass (7 cases, cavernous type), and type D for an epidural hematoma (2 cases, cavernous type with hematoma). Types A and B had frequent single segmental involvement (4/5), whereas types C and D had multisegmental involvement in all. Regardless of MR types, lobular contour (8/14) and a rim of low T2 signal intensity (8/14) of the mass were common. T1 hyperintensity of the mass was occasionally seen (5/14). CONCLUSIONS: Spinal epidural hemangiomas can have various MR imaging features according to their different histopathologic backgrounds. In addition to common features such as solid hypervascularity, lobular contour, and a rim of low T2 signal intensity, T1 hyperintensity or multisegmental involvement may also be a clue in the differential diagnosis of a spinal epidural hemangioma.     

自发性脊髓硬膜外血肿的MRI表现

目的 对自发性脊髓硬膜外血肿(SSEH)的临床及MRI表现进行分析。方法 搜集1994～2001年的8例SSEH患者，其中男5例，女3例，年龄16～50岁。8例患者均无外伤、血液病等病史，1例有高血压病史，于发病4h至3d后分别行MR检查。8例均经手术病理证实。结果 血肿发生于颈椎3例、胸椎2例、颈胸交界部2例、胸腰段1例；血肿位于硬膜外腔的侧后方或正后方，呈梭形，范围长短不一，境界清楚。其中1例血肿为血管畸形(AVM)所致，有2例局部伴有椎间盘突出。血肿信号随时间长短各有差异，在T1WI矢状面和冠状面7例表现为等信号，1例表现为略高信号；在T2WI矢状面和轴面，6例表现为混杂信号，2例表现为混杂高信号。结论 MRI对SSEH的定位、定性及鉴别诊断具有重要作用。     

MR imaging in the diagnosis of spontaneous spinal epidural hematomas

Three patients with spontaneous (idiopathic) spinal epidural hematomas were diagnosed with magnetic resonance (MR) imaging. Magnetic resonance is an accurate, rapid method of localizing and characterizing the hematomas. We believe that MR (where available) should be the primary method of diagnosis in cases in which spinal epidural hematoma is suspected.     

主动脉壁内血肿的影像学诊断及鉴别诊断

目的：探讨主动脉壁内血肿的影像学诊断和鉴别诊断。方法：回顾性分析16例经临床及CT和MRI诊断的主动脉壁内血肿及5例可疑壁内血肿患者的病例资料。12例因胸痛或腹痛入院、经CT或MRI扫描时发现,4例为外伤或内科疾病行胸部或腹部检查时意外发现;另外搜集18例主动脉夹层及11例主动脉瘤患者的影像学资料。结果：16例主动脉壁内血肿,表现为主动脉壁环形增厚7例,新月形增厚5例,环形和新月形增厚同时存在或不规则增厚4例,腔内无内膜片及真假两腔形成,增厚的血管壁内无对比剂进入。5例可疑主动脉壁内血肿表现为管壁轻度环形增厚。18例主动脉夹层均可见真假两腔及内膜片,其中14例其真假腔在横轴面图像上表现为＂D＂字形或反＂D＂字形,真假两腔内均有对比剂进入;11例主动脉瘤表现为血管瘤样扩张或梭形扩张,无真假两腔和内膜片,其中8例可见附壁血栓。结论：CT平扫及增强扫描结合图像后处理技术及MRI多方位成像能够诊断较为典型的主动脉壁内血肿,并与主动脉其它常见疾病相鉴别。     

Echographic and x-ray computed tomographic aspects of intramural hematoma of the duodenum. Apropos of a case

Radiologic imaging in a case of intramural hematoma of duodenum demonstrated typical appearances of the lesion. Ultrasound imaging of the duodenal hematoma was sufficiently characteristic to be used as a basis for a semeiologic discussion and to orientate diagnosis. The relevant literature is reviewed, and value and indications of different imaging techniques for diagnosis and follow up of the hematoma discussed.     

非外伤性脊髓硬膜外血肿的MR诊断

目的　探讨非外伤性脊髓硬膜外血肿的MR表现特点及其鉴别诊断。方法　 14例非外伤性脊髓硬膜外血肿 ,男 9例 ,女5例 ,年龄 4～ 63岁 ,平均 41.3岁。所有病例均无明显的外伤史。常规行T1W矢状位 ,T2 W矢状位及横切位扫描 ,1例行MR增强扫描。结果　 14例非外伤性脊髓硬膜外血肿中 11例位于椎管背侧 ,3例位于椎管腹侧 ,呈新月状或长条带状 ,分别累及 3～ 12个脊髓节段 ,平均 5 .2个脊髓节段。血肿位于颈胸段 4例 ,位于胸段 3例 ,位于胸腰段 5例 ,位于腰段 2例。 10例血肿T1W及T2 W均呈较均质性高信号强度 ,3例血肿T1W及T2 W呈不均质性高信号强度 ,1例于T1W呈中等信号强度 ,T2 W呈较低信号强度。 14例中 1例于血肿内可见低信号的血管流空影 ,术后证实为动静脉畸形。血肿于T1W及T2 W与脊髓之间有一低信号带相隔 ,尤以T2 W显示最佳。 2例受压脊髓于T2 W呈高信号。 1例行MR增强扫描 ,血肿壁轻度强化。结论　MR是诊断非外伤性脊髓硬膜外血肿的最佳检查方法 ,不仅可以清楚地显示血肿的部位及范围 ,而且可以清楚地显示血肿新旧程度及脊髓受损的情况     

Postpartum hemorrhage: Clinical and radiologic aspects

Postpartum hemorrhage (PPH) is a potentially life threatening condition, and it remains the leading cause of maternal morbidity. Uterine atony, lower genital tract lacerations, uterine rupture or inversion, retained products of conception and underlying coagulopathy are some of the common causes of PPH. Most conditions can be diagnosed based on clinical and laboratory evaluation supplemented by ultrasound information. Computed tomography (CT) or magnetic resonance (MR) imaging can provide information for the detection, localization and characterization of PPH in some difficult cases. CT can accurately demonstrate the anatomic location of significant arterial hemorrhage as sites of intravenous contrast material extravasation, which can be as a guide for angiographic intervention. The presence of focal or diffuse intravenous contrast extravasation or a hematoma within the enlarged postpartum uterine cavity on CT can help the diagnosis of uterine atony when the clinical diagnosis of uterine atony is unclear. CT can also provide the information of other alternative conditions such as a puerperal genital hematoma, uterine rupture and concealed hematoma in other sites. MR imaging may be considered as a valuable complement to ultrasound where the ultrasound findings are inconclusive in the diagnosis and differential diagnosis of retained products of conception. Knowledge of the various radiologic appearances of PPH and the correlation with clinical information can ensure correct diagnosis and appropriate and prompt treatment planning in the patients with PPH.     

Spontaneous retropharyngeal hematoma: diagnosis by mr imaging.

Spontaneous retropharyngeal hematoma is an uncommon entity that is difficult to diagnose and may progress rapidly to airway obstruction. We report a case of a 53-year-old man with acute onset of retropharyngeal pain, dysphonia, and dysphagia after vomiting. On CT, a nonspecific retropharyngeal collection was seen. MR imaging demonstrated blood products, suggesting a diagnosis of retropharyngeal hematoma, and the patient was managed conservatively. MR imaging allowed specific diagnosis of a rare condition that is otherwise difficult to diagnose without surgical intervention.     

多层螺旋CT对十二指肠壁内血肿的诊断价值

目的探讨十二指肠肠壁内血肿的多层螺旋CT表现及其诊断价值。资料与方法回顾性分析3例经保守治疗、CT随访证实的十二指肠肠壁血肿患者的多层螺旋CT表现。结果血肿位于十二指肠降段2例,同时累及水平段、降段1例,呈高低混杂或低密度肿块,边缘光整,无增强;肿块与肠壁间有少量气体;肠腔受压变窄;肠壁增厚2例,变薄1例;伴胆总管扩张l例,肠梗阻2例,腹腔积液3例。结论多层螺旋CT能对十二指肠肠壁血肿做出准确、全面诊断,对评估损伤程度、指导临床治疗方案的选择有重要作用。     

Penetrating aortic ulcers: diagnosis with MR imaging

The authors studied seven patients with penetrating aortic ulcers with use of magnetic resonance (MR) imaging. All patients were evaluated for acute chest symptoms, and the presence of aortic ulcers was confirmed by means of angiography in all seven patients. Five patients also underwent computed tomography (CT). Three patients underwent surgical repair of the thoracic aorta. MR findings included intramural hematoma and focal aortic wall ulceration in four patients, focal ulceration in one, focal intramural hematoma in one, and focal intramural hematoma with rupture in one. The diagnosis of intramural hematoma was made by the detection of increased signal intensity on T1- and T2-weighted MR images. MR imaging was superior to angiography in depicting the extent of intramural thrombus, although one ulceration diagnosed at angiography was missed at MR imaging. MR imaging was superior to CT in differentiating acute intramural hematoma from atherosclerotic plaque and chronic intraluminal thrombus, although it did not depict displaced intimal calcification in one patient with extensive intramural hematoma.     

Imaging of nontraumatic hemorrhage of the adrenal gland.

Nontraumatic hemorrhage of the adrenal gland is uncommon. The causes of such hemorrhage can be classified into five categories: (a) stress, (b) hemorrhagic diathesis or coagulopathy, (c) neonatal stress, (d) underlying adrenal tumors, and (e) idiopathic disease. Computed tomography (CT), ultrasonography (US), and magnetic resonance (MR) imaging play an important role in diagnosis and management. CT is the modality of choice for evaluation of adrenal hemorrhage in a patient with a history of stress or a hemorrhagic diathesis or coagulopathy (anticoagulant therapy). CT may yield the first clue to the diagnosis of adrenal insufficiency secondary to bilateral massive adrenal hemorrhage; such insufficiency is rare but life threatening. US is the modality of choice for evaluation of neonatal hematoma, and MR imaging is helpful for further characterization. MR imaging is also useful in the diagnosis of coexistent renal vein thrombosis. When an adrenal abscess is suspected, percutaneous aspiration and drainage under imaging guidance should be performed. Hemorrhage into an adrenal cyst or tumor can cause acute onset of symptoms and signs in a patient without discernible risk factors for adrenal hemorrhage. A hemorrhagic adrenal tumor should be suspected when CT or MR imaging reveals a hemorrhagic adrenal mass of heterogeneous attenuation or signal intensity that demonstrates enhancement.     

MR imaging of intramural duodenal hematoma

The magnetic resonance (MR) appearance of a case of intramural duodenal hematoma is described and compared with CT findings. Due to the paramagnetic effects of iron, the hematoma was more clearly visualized by MR.     

Suprascapular nerve entrapment: evaluation with MR imaging.

Entrapment of the suprascapular nerve is frequently overlooked in the differential diagnosis of shoulder pain. The diagnosis is typically not considered until patients develop severe weakness secondary to atrophy of the spinatus (spinous) musculature that the nerve supplies. Twenty-seven masses were identified adjacent to the suprascapular nerve on magnetic resonance (MR) images of the shoulder; there were 21 ganglion cysts, two synovial sarcomas, one Ewing sarcoma, one chondrosarcoma, one metastatic renal cell carcinoma, and one hematoma associated with a fracture. Atrophy of both the supraspinatus and infraspinatus muscles was seen in association with anteriorly located masses and proximal entrapment of the nerve in 11 cases (40%); isolated atrophy of the infraspinatus muscle was seen in association with posteriorly located masses and distal entrapment of the nerve in nine cases (33%). MR imaging may facilitate the diagnosis of suprascapular nerve entrapment in patients with shoulder pain of unclear origin when perineural masses and atrophy of the spinatus musculature are present.     

Acute identification of cranial burst fracture: comparison between CT and MR imaging findings

BACKGROUND AND PURPOSE: Scalp swelling associated with cranial burst fracture, a widely diastatic skull fracture of infants associated with dural laceration and acute cerebral extrusion, may be confused with that of a simple subgaleal hematoma. Both conditions can also be associated with hemorrhagic shock. We sought to improve the early evaluation of infants believed to have sustained cranial burst fracture by including MR imaging, since this study clearly delineates the dural-cortical interface, the site of injury. METHODS: Seven infants aged 1 through 11 months who sustained cranial burst fractures, all initially imaged with skull radiography and CT, were studied or treated from 1992 through 1996. MR imaging was obtained after resuscitation and stabilization. RESULTS: Surgery or autopsy confirmed MR findings (dural laceration and extracalvarial cerebral tissue) in all seven infants. CONCLUSION: MR imaging allows early diagnosis of skull fracture associated with acute cerebral extrusion.     

Intracranial vascular malformations: MR and CT imaging

Twenty-four patients with 29 cerebrovascular malformations were evaluated with a combination of computed tomography (CT), angiography, and magnetic resonance (MR) imaging. Characteristics of the malformations on MR images were reviewed retrospectively, and a comparative evaluation of MR and CT images was made. Of 14 angiographically evident malformations, 13 intra-axial lesions were detected on both CT and MR images, and one dural malformation gave false-negative results on both modalities. The appearance of parenchymal lesions on MR images closely mirrored characteristic CT findings. Calcific foci were difficult to separate from vessels on both images. Clot was more easily identified on MR images. In the detection of 15 angiographically occult malformations, CT proved more sensitive when focal calcification was the only evidence of their presence. MR study failed to detect two small supratentorial lesions evidenced by faint calcifications on CT scans. In two patients, MR images showed small hemorrhages not detectable by CT, and MR provided strong evidence for the diagnosis of hematoma for 12 lesions. Angiographically evident malformations have a highly characteristic appearance on MR images. MR may be more sensitive than CT in the detection of small hemorrhagic foci associated with cryptic arteriovenous malformations and may add specificity in the diagnosis of occult malformations in some cases, but MR is less sensitive than CT for the detection of small calcified malformations.     

Dissecting and fusiform aneurysms of vertebro-basilar systems

Summary The magnetic resonance (MR) findings of three cases with vertebro-basilar dissecting aneurysms (DA) were compared with those of two cases with vertebro-basilar fusiform aneurysms (FA). No abnormal findings, excepting a dilatation of a signal-void area corresponding to the arterial blood flow, were shown on the MR images in the patients with a FA. In contrast to the FA cases, various abnormalities were detected by the MR studies in all three DA cases. An intimal flap and a double lumen were demonstrated in one case. An intra-mural hematoma was shown in one case. A hematoma neighboring the parent artery was demonstrated in two cases. MR imaging was thought to be useful for detecting intracranial vascular lesions, such as a DA, and for discriminating between a DA and a FA.     

MR imaging of soft-tissue masses of the extraperitoneal spaces.

Magnetic resonance (MR) imaging has an increasing role in evaluating soft-tissue masses of the extraperitoneal spaces. Since the MR imaging features of most soft-tissue masses are nonspecific, prediction of a specific histologic diagnosis remains a challenge for the radiologist. However, there are certain specific MR imaging appearances that are helpful for more accurate diagnosis. Some histologic components, such as myxoid stroma, collagen fibers, calcification, and fat, have characteristic MR imaging features. Recognition of these features can assist the radiologist in limiting the differential diagnosis. Dynamic enhancement patterns can reflect the vascularity of masses and may be useful in diagnosis, especially in differentiating benign from malignant soft-tissue masses. Familiarity with specific signs and knowledge of diagnostic pitfalls are also important for shortening the list of differential diagnoses. Specific signs are the target sign, the bowl of fruit sign, a whorled appearance, a flow void, speckled enhancement, associated lymphadenopathy, and extension into the intervertebral foramen. Diagnostic pitfalls are as follows: a myxoid stroma simulating cystic degeneration and necrosis, collagen fibers simulating hemorrhage, a fat component simulating extraperitoneal fat, extensive intratumoral hemorrhage simulating hematoma, benign masses mimicking malignant ones, malignant masses mimicking benign ones, and peritoneal lesions mimicking extraperitoneal masses.