Retained surgical sponge in the thigh: report of the third known case in the limb

We report a retained surgical sponge (gossypiboma) in the thigh, which mimicked a neoplasm. A 25-year-old man, who had a past history of external fixation for femoral shaft fracture, complained of swelling in the left thigh with pain. A radiograph of the thigh showed periosteal reaction. T1-weighted magnetic resonance (MR) images showed a well-defined mass with heterogenous signal intensity, and T2-weighted images showed tortuous lines of low signal intensity within the mass. Surgical excision revealed a retained gauze sponge within the mass. Histopathological examination revealed foreign body reaction related to the retained gauze sponge. Our case, the third to our knowledge of gossypiboma in a limb, demonstrated characteristic MR imaging findings.     

Rectal cancer: mesorectal lymph nodes at MR imaging with USPIO versus histopathologic findings--initial observations

PURPOSE: To compare histopathologic findings with appearances of mesorectal lymph nodes at magnetic resonance (MR) imaging with ultrasmall particles of iron oxide (USPIO) in rectal cancer. MATERIALS AND METHODS: Mesorectal lymph nodes in 12 patients with adenocarcinoma of the rectum were evaluated with USPIO and high-spatial-resolution MR imaging. Appearance and signal intensity of lymph nodes at T2- and T2*-weighted imaging were recorded before and after USPIO administration. Two radiologists visually assessed pattern of enhancement; interobserver agreement was tested with the kappa statistic. After total mesorectal excision, MR imaging of surgical specimens was performed, and it enabled node-by-node correlation with histopathologic findings. RESULTS: Appearances of 74 nodes at in vivo MR imaging were compared with histopathologic findings. Sixty-eight nodes were nonmalignant (34 were normal, 34 showed reactive changes); six nodes were malignant. Four patterns of USPIO uptake were demonstrated at T2*-weighted imaging: uniform low signal intensity, central low signal intensity, eccentric high signal intensity, and uniform high signal intensity. Two radiologists showed good interobserver agreement (kappa = 0.88, P <.01) in classification of nodes into these four categories. Sixty-five (96%) of 68 nonmalignant nodes showed uniform or central low-signal-intensity patterns; 16 (47%) of 34 reactive nodes showed central low-signal-intensity patterns. Compared with uniform low-signal-intensity pattern, central low-signal-intensity pattern was more commonly observed in reactive nodes (P <.01, chi(2) test; positive predictive value, 67%; 95% CI: 47%, 87%). Eccentric and uniform high-signal-intensity patterns were observed in lymph nodes that contained metastases larger than 1 mm in diameter. CONCLUSION: Mesorectal lymph nodes can be characterized by using USPIO and T2*-weighted MR imaging. Uniform and central low-signal-intensity patterns are features of nonmalignant nodes. Reactive nodes frequently show central low signal intensity at T2*-weighted imaging.     

Gossypiboma in abdomen and pelvis: MRI findings in four patients

OBJECTIVE: The purpose of our study was to describe the MRI features of gossypiboma and correlate the MRI findings with the pathologic findings in four patients. CONCLUSION: On MRI, gossypiboma in the abdomen and pelvis manifested as a well-defined mass that showed a peripheral wall of low signal intensity at T1- and T2-weighted imaging and enhancement at contrast-enhanced T1-weighted imaging. The whorled stripes within the central portion were characteristically shown as low signal at T2-weighted imaging, and the serrated contour in the inner border of the peripheral wall was shown at contrast-enhanced T1-weighted imaging. Histopathologically, the peripheral wall showed granulomatous inflammation with massive fibrosis and foam cell and multinucleated giant cell infiltrations, whereas the whorled stripes within the central portion were gauze fibers. If a patient has a history of a previous operation, the possibility of gossypiboma should be suggested when the central whorled stripes or serrated contour in the inner border of the peripheral wall is present at MRI.     

Magnetic resonance imaging of retained surgical sponges case report

The magnetic resonance imaging (MRI) features of sponges retained postsurgically in three patients are described. MRI depicted these as well-defined round masses, which were of low signal intensity on T1-weighted images and very high signal intensity on T2-weighted images. We scrutinized these masses on T2-weighted images. MRI revealed the low-signal-intensity structures to have wavy, striped, and/or spotted appearances, which raised the suspicion that they might be retained surgical sponges within mass lesions.     

Discrimination of metastatic from acute osteoporotic compression spinal fractures with MR imaging.

A study was performed to determine which magnetic resonance (MR) imaging findings are useful in discrimination between metastatic compression fractures and acute osteoporotic compression fractures of the spine. The MR imaging findings in 27 patients with metastatic compression fractures and 55 patients with acute osteoporotic compression fractures were compared by using the chi(2) test. MR imaging findings suggestive of metastatic compression fractures were as follows: a convex posterior border of the vertebral body, abnormal signal intensity of the pedicle or posterior element, an epidural mass, an encasing epidural mass, a focal paraspinal mass, and other spinal metastases. MR imaging findings suggestive of acute osteoporotic compression fractures were as follows: a low-signal-intensity band on T1- and T2-weighted images, spared normal bone marrow signal intensity of the vertebral body, retropulsion of a posterior bone fragment, and multiple compression fractures. The signal intensity on fast spin-echo T2-weighted images obtained without fat suppression played little role in distinguishing between metastatic compression fractures and acute osteoporotic compression fractures. Copyright RSNA, 2003.     

MR imaging of middle ear cholesteatomas

We prospectively evaluated MR images of 14 patients who had chronic otitis media and who were suspected of having cholesteatomas on otologic examination and/or on high resolution CT. Cholesteatomas were verified in the middle ear and/or mastoid at surgery in nine patients. Cholesteatomas appeared isointense relative to gray matter on T1-weighted spin echo MR images (T1WI) and hyperintense on T2-weighted spin echo MR images (T2WI) in eight patients. Two cholesterol granulomas appeared hyperintense on both T1WI and T2WI. In three patients with chronic otitis media the associated mixed granulation tissue and fluid collection was revealed as nonspecific, heterogeneous signal intensity in two cases. In the third case the signal intensity was similar to that found in cholesteatomas.     

Hip pain in three children accompanied by transient abnormal findings on MR images

In a study of three children experiencing hip pain, low-signal-intensity patterns in the femoral head on T1-weighted magnetic resonance (MR) images eventually resolved, reverting to the normal signal patterns. These findings occurred in conjunction with documented clinical improvement of the patients' condition. T2-weighted images revealed isointense signals initially at the abnormal sites. Isointense signals prevailed on follow-up T2-weighted images. These MR imaging findings are likely due to transient bone marrow edema. These findings support the apparent sensitivity of MR imaging in the evaluation of marrow-based pathologic processes. Some pediatric patients with hip pain may have signs of transient bone marrow edema, rather than avascular necrosis, on MR images. Conservative management should be considered in such cases.     

磁共振信号强度在胸膜疾病中的诊断意义

目的评价磁共振信号强度在胸膜疾病中的诊断价值.方法48例不同胸膜疾病病人在Philips0.5T扫描仪下行MR检查.成像常规为T1WI、T2WI快速自旋回波扫描,所有病例均在病理证实结合临床资料下得出恶性或良性胸膜疾病的诊断.恶性疾病包括胸膜间皮瘤(n=10)、胸膜转移瘤(n=18),良性疾病包括结核性胸膜炎(n=9)、胸膜肥厚(n=7)、纤维胸(n=1)、脓胸(n=2)和胸膜炎性假瘤(n=1).将各种胸膜疾病T1WI、T2WI上绝对信号强度(ASI),病灶信号与肌肉信号的对比噪声比(CNR),信号强度比(SIR)分别进行测量或计算,判断它们在良、恶性胸膜疾病之间,胸膜间皮瘤与胸膜转移瘤之间是否存在差别.结果ASI在良、恶性胸膜疾病之间,胸膜间皮瘤与转移瘤之间均无显著差异,CNR在良、恶性胸膜疾病之间于T2WI上有差别(P＜0.01),而SIR在良、恶性胸膜疾病之间于T1WI、T2WI上均有极显著差异(P＜0.001),同时,还在胸膜间皮瘤与转移瘤之间于T2WI上存在差别(P＜0.05).结论磁共振信号强度在胸膜疾病鉴别诊断中有重要意义,其中SIR最具有诊断价值.MR信号强度在T2WI上比T1WI上更具有区分不同胸膜疾病的能力.     

CT and MRI findings of a solitary extramedullary plasmacytoma of the oropharynx: case report

We report a case of solitary extramedullary plasmacytoma (SEP) of the oropharynx. A 53-year-old man presented who had had bloody phlegm and a sore throat for a few days. A mass was endoscopically detected in his right posterior oropharyngeal wall, and biopsy revealed a neoplasm consisting of a uniform population of plasma cells. Computed tomography (CT) showed a broad-based papillary soft tissue density mass projecting into the oropharynx from the right posterior wall of the pharynx, and post-contrast CT showed marked enhancement of the tumor. The tumor showed slightly higher signal intensity compared with surrounding muscle on MR Tl-weighted images (T1WI) and high signal intensity on MR T2-weighted images (T2WI). The mass showed homogeneous enhancement on post-contrast T1WI. Further clinical examination showed an absence of multiple myeloma (MM). The patient was diagnosed as having SEP. Following radiation therapy, a reduction in tumor size was observed. Although SEP is a rare tumor, it should be included in the differential diagnosis of tumors of the oropharynx because of its imaging similarities to other, more common malignant tumors, such as squamous cell carcinoma and lymphoma.     

MR imaging of ovarian hemorrhage

BACKGROUND: To review MR appearances of ovarian hemorrhage, and to describe its characteristic imaging findings. METHODS: 12 women (age range, 20-44, mean, 26 years) with suspected ovarian hemorrhage underwent pelvic MR examinations. We retrospectively reviewed MR findings regarding signal intensities, localization, and wall enhancement of adnexal masses, and signal intensities of ascites. RESULTS: Adnexal masses were detected in all cases. In eight cases, adnexal mass exhibited intermediate signal intensity on T1WI, and intermediate to low signal intensity on T2WI. In other case, adnexal mass exhibited marked hyperintensity on T1WI. In the remaining three cases, cystic mass with low signal intensity on T1WI and high signal intensity on T2WI was noted. Ascites was present in all cases, and showed intermediate signal on T1WI and intermediate to low signal on T2WI. CONCLUSIONS: In ovarian hemorrhage, hemorrhagic ascites and adnexal mass was visualized with specific MR signal intensity. Due to its sensitivity for identifying blood, MR imaging is useful in the diagnosis of ovarian hemorrhage, especially when ultrasonography findings are not definitive.     

乳腺MR灌注时间-信号强度曲线表现及价值研究

目的探讨乳腺MRT2*WI首次通过灌注时间-信号强度曲线(TIC)表现及其在乳腺病变鉴别诊断中的价值。资料与方法对40例乳腺肿瘤患者行乳腺动态增强成像扫描,绘制T2*WI首次通过灌注TIC及T1WI动态增强TIC。采用Fisher’s确切概率法检验,判定良、恶性病灶T1WI动态增强及灌注TIC的差异。结果良、恶性病灶灌注TIC之间差异具有显著性统计学意义(P<0.05=0.000);良、恶性病灶T1WI动态增强TIC之间差异有显著性统计学意义(P<0.05=0.011),但在平台型曲线类型中良恶性病灶有较大重叠。结论乳腺MR灌注TIC在良、恶性病灶具有显著差别,恶性病灶灌注TIC主要表现为信号快速下降后缓慢回升(A型)与快速下降后不回升(B型);良性病灶灌注TIC主要表现为平直型(C型)及缓慢上升后平台型(D型)。灌注TIC与病灶形态学结合可大大提高乳腺疾病诊断的准确性。     

MR imaging differentiation of soft-tissue hemangiomas from malignant soft-tissue masses

OBJECTIVE: The purpose of this study was to determine whether MR imaging features can reliably distinguish hemangiomas from malignant soft-tissue masses. MATERIALS AND METHODS: We retrospectively reviewed MR imaging studies of 22 patients with soft-tissue hemangiomas and 22 patients with malignant soft-tissue masses. Images were reviewed and agreement reached by a consensus interpretation of two observers and by an independent observer. Masses were evaluated for signal intensity on T1- and T2-weighted images, for enhancement with gadolinium administration, and for morphology (lobulation, septation, central low-intensity dots). Lesion T2 signal and lesion enhancement with gadolinium administration were also objectively measured using regions of interest and comparison with skeletal muscle. RESULTS: Signal intensity on T1-weighted imaging of hemangiomas and malignant soft-tissue masses was similar. Subjective analysis showed greater T2 signal and gadolinium enhancement in hemangiomas; however, the differences were not statistically significant on objective analysis. Lobulation, septation, and central low-signal-intensity dots were all more common in hemangiomas, with statistical significance achieved; the combination of all three findings was specific for hemangioma. CONCLUSION: Although no single MR imaging feature was diagnostic in this study, analysis of lesion morphology, signal intensity, and enhancement with gadolinium allowed MR imaging differentiation of hemangiomas from malignant soft-tissue masses.     

下肢神经源性肿瘤的MRI表现

目的 评估下肢神经源性肿瘤的MR表现。方法 回顾性分析5例经病理证实的下肢神经源性肿瘤的MR表现，其中4例为神经鞘瘤(3例良性，1例恶性)，1例为恶性神经纤维瘤；肿瘤分别位于小腿(2例)、腘区(1例)、大腿(1例)和股区(1例)。5例均行常规MR扫描，应用T1、T2加权序列作轴面、冠状面和矢状面扫描，2例良性神经鞘瘤应用T1WSE作增强扫描。结果 在T1WI2例良性神经鞘瘤呈等信号强度，1例良性神经鞘瘤、1例恶性神经鞘瘤和1例恶性神经纤维瘤呈不均质的低一中等信号强度。在T2WI5例肿瘤均呈不均质高信号。2例神经鞘瘤可见靶征，表现为瘤体中央为低信号区，其周围为高信号区，于T2WI显示清楚。结论 MRI有利于明确肿瘤的位置和范围，以及外科治疗计划的制定。靶征对周围神经源性肿瘤的诊断是1种有价值的征象。     

Uterine contractions: Possible diagnostic pitfall at MR imaging

A total of 206 nongravid patients with various gynecologic problems underwent pelvic magnetic resonance (MR) examinations that included both sagittal T2-weighted and contrast agent–enhanced T1-weighted images. MR images were retrospectively reviewed to identify changes in endometrial configuration on serial images obtained during the same MR examination. In 20 MR examinations (all in women of reproductive age), endometrial distortion due to myometrial bulging was noted on T2-weighted or contrast-enhanced T1-weighted images. It was absent on other MR images obtained at different times. Myometrial bulging exhibited low signal intensity in 18 examinations. The finding resembled adenomyosis or leiomyoma on T2-weighted or contrast-enhanced T1-weighted images. These results evidence the presence of transient myometrial bulging and transient low-intensity myometrium in the nongravid uterus. This phenomenon is thought to represent uterine contraction. Clinicians should be aware of the potential presence of transient low-signal-intensity myometrial bulging that could present diagnostic problems in the normal uterus.     

Microwave coagulation therapy on hepatomas: CT and MR appearance after therapy

Laparoscopic microwave coagulation (LMC) for hepatocellular carcinomas (HCCs) was performed on 26 HCCs in 17 patients. Contrast-enhanced CT (CECT) and MR images (T1-weighted imaging [T1WI], T2WI, gadolinium-diethylenetriamine pentaacetic acid [Gd-DTPA] T1WI) were obtained to determine changes over time. The irradiated center exhibited low to moderate intensity with surrounded high intensity (HI) on T2WI and Gd-DTPA T1WI. On T1WI, lesions showed four patterns of intensity: uniform HI (30.8%), arcuate HI (26.9%), mainly low with spot HI (30.8%), and isointensity to hypointensity (11.5%). Follow-up imaging at more than 170 days revealed isointensity to hypointensity on T1WI (96.2%) and reduced HI on T2-weighted imaging (T2WI) and Gd-DTPA T1WI. All lesions became less conspicuous and were reduced in volume. HCC shows time-related changes in signals and size after LMC. Identifying the irradiated lesion is necessary to estimate the adequacy of treatment by comparison with the pretherapeutic image.     

Meniscal tears: MR and arthrographic findings after arthroscopic repair

Magnetic resonance (MR) imaging was performed on 29 previously repaired menisci and one conservatively treated meniscus (total, 30 menisci). Intermediate- and T1-weighted MR sequences revealed persistent signal intensity extending to an articular surface (grade 3 signal intensity) in 27 of the 30 menisci. On T2-weighted images, seven of the 30 menisci were found to contain unequivocally higher signal intensity, defined by a full-thickness defect (grade 3 signal intensity involving two articular surfaces) increasing in signal intensity to a level equivalent to that of joint fluid. The MR imaging and arthrographic appearances of 23 of the 30 menisci were compared. Arthrographic examination revealed partial or complete healing in 13 menisci and tears in 10. The presence of grade 3 signal intensity on intermediate- and T1-weighted MR images did not reliably predict a tear seen at arthrography. Unequivocally higher signal intensity on T2-weighted images is a useful sign in the prediction of a persistent meniscal tear (sensitivity, 60%; specificity, 92%; P less than .02). Since presence of grade 3 signal intensity on intermediate- and T1-weighted images does not reliably predict a tear and unequivocal T2 increase in intensity has a sensitivity of only 60%, arthrography should be considered for assessment of the symptomatic, previously repaired meniscus.     

精囊出血的MRI诊断(附5例报告)

目的 :分析精囊出血的MR表现 ,提高对精囊出血病变的认识。方法 :对 5例精囊出血的病例分别采用轴位T1WI、T2 WI、T1WI脂肪抑制序列及矢状位T2 WI序列行MR检查 ,并回顾性分析MRI表现。结果 :精囊出血表现为条状、结节状或纡曲短T1、长T2 异常信号 ,T1压脂后病灶显示更清晰并同周围组织区分开来。结论 :各种序列结合使用的MRI是精囊出血的可靠的非创伤性诊断手段。     

Pseudolesions related to uterine contraction: characterization with multiphase-multisection T2-weighted MR imaging

PURPOSE: To evaluate whether multiphase-multisection T2-weighted magnetic resonance (MR) images help exclude pseudolesions mimicking leiomyoma and adenomyosis on static T2-weighted fast spin-echo (FSE) MR images and to characterize temporal changes in uterine signal intensity related to uterine contraction. MATERIALS AND METHODS: T2-weighted FSE and multiphase-multisection single-shot FSE (SSFSE) MR imaging were performed in 43 patients who underwent hysterectomy. Each imaging set was evaluated separately by two independent readers, and receiver operating characteristic analysis was performed. In the 43 patients and in 49 other patients suspected of having pelvic abnormality, a combination of signal intensity changes on FSE and SSFSE MR images was classified into five patterns, and temporal low-signal-intensity changes on SSFSE MR images were characterized. RESULTS: For detection of leiomyoma on FSE and SSFSE MR images, the respective values of the area under the receiver operating characteristic curve were 0.98 and 0.97 for reader 1 and 0.96 and 0.96 for reader 2; for detection of adenomyosis on FSE and SSFSE MR images, the respective values were 0.82 and 0.84 for reader 1 and 0.80 and 0.89 for reader 2 (P >.05). SSFSE MR images helped exclude pseudolesions in 1%-3% cases of leiomyoma and in 3%-4% cases of adenomyosis. Temporal signal intensity changes were observed in 53% of 368 segments. The most frequent shape of temporal low signal intensity was diffuse followed by ill-defined focal type. Characteristic shape of temporal low signal intensities was band- or sticklike, which was observed in as many as 19% of 368 segments. CONCLUSION: Multiphase-multisection T2-weighted SSFSE MR images do not improve accuracy in detection of leiomyoma and adenomyosis compared with FSE MR images; however, they helped characterize features of temporal low signal intensities in the uterus, which are related to uterine contractions.     

MR of intracranial epidermoid tumors: correlation of in vivo imaging with in vitro 13C spectroscopy

We analyzed the MR findings of five patients with benign intracranial epithelial tumors, commonly called epidermoids. The neoplasms were categorized into two groups on the basis of T1-weighted MR signal intensity (relative to brain): high-signal-intensity masses (short T1) and low-signal-intensity masses (long T1). Surgical specimens were obtained and analyzed by means of 13C MR spectroscopy. Epidermoids with short T1 values (white epidermoids) had a high lipid content comprising mixed triglycerides containing unsaturated fatty acid residues. Epidermoids with long T1 values (black epidermoids) exhibited a much reduced lipid content with no triglycerides or fatty acids. There was evidence of trace amounts of cholesterol in the black epidermoids. Our data indicate that epidermoids are a heterogeneous group of neoplasms that behave differently with T1-weighted MR imaging and 13C MR spectroscopy. The combination of MR imaging and spectroscopy holds the potential of further elucidating the nature of epidermoids as well as of other forms of neoplasms.     

MR features of aneurysmal bone cyst of the mandible and characteristics distinguishing it from other lesions

Aneurysmal bone cyst (ABC) is a relatively rare, non-neoplastic expansile lesion of bone. Bleeding may occur during an operation or biopsy for ABC, as this cyst is an aneurys with numerous pools of blood. Therefore, it is necessary to diagnose ABC before treatment or biopsy. In the present report, we describe the characteristic computed tomography (CT) and magnetic resonance imaging (MRI) features of ABC in the mandible. Based on the literature and on our own experiences, we compare with the features of ABC with the corresponding features of other lesions showing similar conventional radiographic appearances. In the present case, bone-targeting CT showed the characteristic feature, which reflected the histopathological appearance of a partially cystic meshwork divided by coarse septa. MRI showed almost homogeneous intermediate signal intensity, including a partial slight low-signal-intensity area on the T1-weighted image, and homogeneous high signal intensity, which showed a 'bubbly' appearance, on T2-weighted image. On the enhanced T1-weighted image, the intermediate signal intensity areas apart from the areas that showed slight low-signal intensity on the non-enhanced T1-weighted image, were well enhanced. This creates a 'honeycomb' appearance. The 'meshwork' appearance on bone-targeting CT, the 'bubbly' appearance on the T2WI and the 'honeycomb' appearance on Gd-T1WI may be the characteristic features of ABC.