慢性侵袭性真菌性鼻窦炎的CT和MRI诊断

目的探讨慢性侵袭性真菌性鼻窦炎的CT和MRI表现及诊断价值。方法回顾性分析经手术、组织病理学证实的10例慢性侵袭性真菌性鼻窦炎的影像学资料。结果慢性侵袭性真菌性鼻窦炎发生于蝶窦5例，上颌窦3例，筛窦2例。CT表现：受累窦腔内充以软组织影，其中1例伴斑点状钙化；窦壁骨质破坏，同时伴周围骨质增生肥厚。MRI表现：T1WI为低信号（与脑实质比较，以下相同）2例，等信号7例；T2WI信号不均匀，7例以低信号为主，2例以高信号为主；增强后病变明显强化。侵犯邻近结构：眼眶9例，其中6例累及眶尖区，可见不规则软组织肿块影，与邻近眼外肌分界不清楚，7例包绕视神经；6例侵犯海绵窦，可见形态不一的软组织影；脑膜增厚、强化5例，3例侵犯脑实质，表现为水肿1例，肉芽肿2例；4例侵犯翼腭窝及颞下窝；3例鼻咽部软组织增厚；2例上颌神经和1例下颌神经明显增粗、强化；3例面颊部软组织肿胀；1例硬腭骨质破坏。结论窦壁骨质破坏伴硬化、MR T2WI低信号、易侵犯眶尖及海绵窦为本病特征性影像学表现。结合CT和MRI2种检查方法能够对本病的诊断、鉴别和治疗提供更可靠的信息。     

Mucoceles of the paranasal sinuses: MR imaging with CT correlation

The MR findings in six cases of paranasal sinus mucoceles are described. Two basic MR appearances were encountered: either moderate to marked signal hypointensity in the expanded sinuses on T1- and T2-weighted images (four patients) or moderate to marked signal hyperintensity on T1- and T2-weighted images (two patients). These patterns appear to represent inspissated or hydrated sinus contents, respectively. CT correlation revealed hyperdense mucoceles in the decreased MR signal group and hypo- or isodense mucoceles in the increased MR signal group. Superimposed allergic Aspergillus sinusitis was also present in two patients with hypointense mucoceles on MR.     

MR of esthesioneuroblastoma (olfactory neuroblastoma) and appearance after craniofacial resection.

PURPOSETo analyze the MR characteristics of a series of patients with esthesioneuroblastoma and discuss the typical surgery and its postoperative MR appearance.METHODSThe MR studies of 15 patients with the pathologic diagnosis of esthesioneuroblastoma (also known as olfactory neuroblastoma) were retrospectively reviewed and correlated with CT and surgical findings. The postoperative MR studies of 10 patients who underwent craniofacial resection were also reviewed.RESULTSIn all cases the tumors arose in the superior nasal cavity and extended into the ethmoid cells. In some instances the tumors extended into the other paranasal sinuses, orbits, anterior cranial fossa, and cavernous sinus. The tumors were typically expansile and destructive in their growth patterns. Compared with brain gray matter, the tumors were hypointense on T1-weighted images and isointense to hyperintense on T2-weighted images. Nine tumors were heterogeneous and 6 were homogeneous. Contrast enhancement ranged from mild to marked. MR was useful for characterizing the various tissues and distinguishing fluid in the postoperative nasal cavity.CONCLUSIONSEsthesioneuroblastoma, although an uncommon tumor, may be suspected in lesions of the superior nasal cavity demonstrating both expansile and destructive growth properties. The MR findings are otherwise nonspecific. MR is the imaging modality of choice for depicting local tumor extension and evaluating for recurrence after craniofacial resection.     

Non-invasive aspergillosis of the paranasal sinuses: CT and MRI findings

Aspergillosis is the most common fungal infection of the paranasal sinuses, and needs to be recognized because it requires surgical removal. Twenty proven cases of aspergillosis of the paranasal sinuses are reported here. CT was performed in all the cases and MRI in 2 cases. The maxillary sinus was affected in 19 patients and the sphenoid sinus in 1. Mycosis was unilateral in all but 1 of the cases. Foci of increased attenuation at CT were observed in 18 cases, with calcification in 10 cases and/or dental material in 13 cases. An increased bony wall thickness was observed in 16 cases. All the patients but 1 had at least one of the signs. At MRI the fungal mass displayed a hypointense signal on T1- and T2-weighted images. No enhancement was noted on post-contrast T1-weighted images. The diagnosis of paranasal sinus aspergillosis is suggested by the CT findings, when a hyperdense mass with calcifications and/or dental material is noted with thickening of the sinus wall. MRI may have a complementary diagnostic role in doubtful cases. Correspondence to: Y. Robert     

非侵袭性真菌性上颌窦炎的CT诊断

目的总结非侵袭性真菌性上颌窦炎的CT表现特征,以提高本病的正确诊断率。方法对经手术、病理证实的50例非侵袭性真菌性上颌窦炎的CT表现进行回顾性分析。结果 43例病变累及一侧上颌窦,7例累及同侧筛窦及鼻腔。病变窦腔内充以软组织密度影,内见斑点斑块状钙化36例,窦腔高密度影内见气泡影19例。34例见上颌窦窦壁骨质改变,窦壁骨质增生硬化26例;窦壁骨质吸收破坏24例。结论非侵袭性真菌性上颌窦炎具有特征性的CT表现,CT对该病的诊断有较高价值。     

Sinonasal psammomatoid ossifying fibromas: CT and MR manifestations

Five cases of pathologically proved psammomatoid ossifying fibromas of the sinonasal area are presented. All five cases were examined by CT and in three cases MR imaging was performed before and after injection of gadopentetate dimeglumine. The lesions were located in the sphenoethmoidal area and extended over the nasal cavity or orbit in four cases. In one case, the lesion occurred at the perpendicular plate of the ethmoid bone with preservation of the ethmoidal sinus. On CT, all the lesions were expansile and circumscribed by a thick bony wall. Internal septations of bone density (four cases) or enhancing soft-tissue density (one case) were seen and internal content was low in density in all but one from which blood was aspirated. On MR, the bony walls were isointense with gray matter on T1-weighted images and were seen as areas of low intensity on T2-weighted images. The lesions significantly enhanced after injection of contrast material. A well-circumscribed multiloculated expansile mass with a thick wall of bone density on CT scans and enhancement of this area on postcontrast MR images is strongly suggestive of psammomatoid ossifying fibroma.     

Cerebral venous angiomas

Summary Sixteen cases of cerebral venous angiomas, seven cerebellar and nine supratentorial were imaged by magnetic resonance, using a T1 sequence and a motion compensated T2 sequence. The transcerebral draining vein of the lesion could be identified in thirteen out of sixteen patients. On T1-weighted images all the lesions were hypointense. On T2-weighted images, five lesions were hypointense, and eleven were hyperintense consistent with slow flow. In three cases the lesion was hemorrhagic. Three lesions with hypointense aspect on T1 and hyperintense aspect on T2-weighted images were only seen in retrospect, due to partial volume averaging in two and concomitant chronic hemorrhage in one. Before contrast, the peripheral dilated medullary veins could only be identified in five cases. On T2-weighted images, in three of these lesions the signal was higher than in the draining veins, pointing to a slower flow. After intravenous administration of Gadolinium, performed in twelve patients, the main transcerebral draining vein as well as the peripheral medullary veins could be well identified in all patients.     

真菌性蝶窦炎的影像诊断和鉴别诊断

目的:探讨蝶窦真菌感染的影像学特征、诊断和鉴别诊断。方法:回顾性分析11例经病理证实的真菌性蝶窦炎的临床和影像学检查资料。结果:CT与MRI表现为窦腔内结节样软组织密度影8例(73%);伴有沙粒状、小条片状、团块状的钙化6(45%)例;累及后组筛窦5例(45%),伴窦腔扩大7例(64%);局限性骨质增生和破坏4例(36%)。结论:真菌性蝶窦炎具有较特征性影像学表现,鉴别诊断要考虑一般性炎症、息肉、粘液囊肿和肿瘤。     

Hypointense thrombus on T2-weighted MR imaging: a potential pitfall in the diagnosis of dural sinus thrombosis.

Purpose: To determine the frequency of hypointense appearance of dural sinus thrombosis on T2-weighted images, which may mimic a normal flow void, and when possible correlate with appearance on T1-weighted images. Methods and Materials: Retrospective review of radiology files showed 51 patients with a discharge diagnosis of dural sinus thrombosis who underwent MR imaging during the period 1986-1998. These images were reviewed by an experienced neuroradiologist for appearance on T2-weighted images. This process yielded five cases in which a hypointense appearance on this pulse sequence simulated a normal flow void. An additional two cases were added from the teaching files of two other institutions giving a total of seven cases (13% of studies). The resulting study population consisted of five women and two men (mean age 27.1 years). T1 weighted images were available in five patients. In two patients MR venography was available, but not T1-weighted images. The diagnosis of dural sinus thrombosis was based solely on absence of flow void on T1-weighted images in one case, solely on absence of flow void on MR venography in two cases and absence of flow void on T1-weighted images in conjunction with MR venography or gradient echo findings in 4 patients. All images were obtained on a 1.5 T magnet (GE Medical Systems; Milwaukee, Wisconsin). Results: In all patients hypointense signal of thrombus was isointense with normal flow voids in other dural sinuses on T2-weighted images. In all cases in which T1-weighted images were available, the signal intensity of thrombus was isointense to gray matter. Conclusion: Hypointense appearance of thrombus on T2-weighted images is a potential pitfall in the MR diagnosis of dural sinus thrombosis. Because thrombus in this stage of evolution appears isointense to gray matter on T1-weighted images, careful attention must be paid to other sequences to avoid this pitfall.     

Configurational MR characteristics of metastatic brain tumors

Magnetic resonance (MR) characteristics of metastatic brain tumors (MBTs) were studied using 15 cases (13 males and 2 females whose ages ranged from 32–78 yr, with the mean age of 57.8 yr;12 adenocarcinomas, 2 squamous-cell carcinomas, 2 large-cell carcinomas). Nine cases showed hypointensities and five showed isointensities on T1-weighted images. Six cases showed markedly hypo- or hypointensities, two showed isointensities, and six showed markedly hyper- or hyperintensities on T2-weighted images. One case was markedly hyperintense on both T1- and T2-weighted images. The decrease of the signal intensity on the T2-weighted image was the main MR characteristic. A hypointense peritumoral rim was seen in four of the six hyperintense tumors on T2-weighted images. There was no correlation between the signal intensity and the histological classification.     

Focal nodular hyperplasia of the liver: MR imaging and pathologic correlation in 37 patients.

Thirty-seven patients with 48 lesions of focal nodular hyperplasia (FNH) underwent preoperative magnetic resonance (MR) examination and surgical resection. Sixteen lesions were imaged at 0.5 T with T1- and T2-weighted spin-echo sequences; 32 lesions were imaged at 2 T with T1-and T2-weighted spin-echo and gradient-recalled-echo sequences. Contrast material-enhanced MR imaging was performed in 20 lesions. MR imaging failed to depict six tumors that were less than 3 cm in diameter. Typical appearance was present in 18 of the 42 (43%) lesions seen at MR. Atypical lesion features included no scar (n = 15), hypointense scar on T2-weighted images (n = 7), pseudocapsule (n = 6), strong hyperintense lesion on T2-weighted images (n = 3), diffuse hyperintensity on T1-weighted images (n = 3), and heterogeneous lesion (n = 1). Comparison between findings at MR imaging and at histopathologic examination was performed in 38 lesions: There was good correlation between presence and size of the scar on both examinations. In 13 of 20 (65%) of the hyperintense scars on T2-weighted images, edema was prominent, whereas in five of the seven (71%) hypointense scars on T2-weighted images, edema was absent or low.     

Focal nodular hyperplasia of the liver: MR findings in 35 proved cases

MR images of 28 patients with 35 lesions of hepatic focal nodular hyperplasia were reviewed to determine the frequency of findings considered typical of this condition (isointensity on T1- and T2-weighted pulse sequences, a central hyperintense scar on T2-weighted images, and homogeneous signal intensity). Fifteen lesions were imaged at 0.6 T with T1- and T2-weighted spin-echo (SE) pulse sequences; 20 lesions were imaged at 1.5 T with T1-weighted SE and gradient-echo pulse sequences and T2-weighted SE pulse sequences. Diagnosis of focal nodular hyperplasia was made pathologically in 25 patients, with nuclear scintigraphy in four, and with follow-up imaging in six. Only seven lesions (20%) were isointense relative to normal liver on both T1- and T2-weighted images. On T1-weighted SE images, 21 lesions (60%) were isointense relative to normal liver, 12 (34%) were hypointense, and two (6%) were hyperintense. On T2-weighted SE images, 12 lesions (34%) were isointense and 23 (66%) were hyperintense relative to normal liver. A central scar was present in 17 lesions (49%) and was hypointense relative to the lesion on T1-weighted images and hyperintense on T2-weighted images. Twenty lesions (57%) were of homogeneous signal intensity throughout the lesion, except for the presence of a central scar. All three MR imaging characteristics were present in three cases (9%). We conclude that hepatic focal nodular hyperplasia has a wide range of signal intensity on MR imaging.     

Pseudolesion in segment IV of the liver on MRI: prevalence and morphology in 250 cirrhotic livers compared with 250 normal livers

PURPOSE: The goal of our study was to assess the prevalence of pseudolesion in segment IV of the liver on MRI in patients with and without liver cirrhosis. METHOD: Patients were divided into three groups: 10 patients with angiographically confirmed aberrant gastric venous drainage and liver cirrhosis (Group 1), 250 consecutively selected patients with liver cirrhosis (Group 2), and 250 with normal liver (Group 3). The signal intensity of pseudolesion in segment IV on T1- and T2-weighted MRI in the 510 patients was analyzed. RESULTS: In Group 1, five pseudolesions were visible and hyperintense on T1-weighted images. On T2-weighted images, four were visible and hypointense. In Group 2, 11 were seen (4.4%). All were hyperintense on T1-weighted images. Five were hypointense on T2-weighted images. In Group 3, one pseudolesion was seen (0.4%). CONCLUSION: The prevalence of pseudolesion in segment IV on MRI is higher in liver cirrhosis than in normal liver. The lesion is hyperintense on T1-weighted images when visible.     

Hypointense MR signal in chronically inspissated sinonasal secretions

Six patients with chronically obstructed sinuses were examined with computed tomography (CT) and magnetic resonance (MR) imaging prior to surgical decompression. In all six patients, hypointense signal was present on all MR sequences despite CT evidence of the presence of high-attenuation material filling the sinus. At surgery, all specimens were viscid or pastelike with no evidence of hemorrhagic products as a cause for the MR findings. Sinonasal secretions may have a spectrum of MR signal intensity, ranging from hyperintense to signal void with all pulse sequences. These findings must be kept in mind when interpreting images of patients with suspected chronic sinusitis.     

Mottled MR appearance of a hyperacute intracerebral hemorrhage at 0.5 T

A hypertensive patient was examined by CT and magnetic resonance (0.5 T) within 3 h from stroke onset. Computed tomography revealed a thalamocapsular hemorrhage. Hematoma was isointense to the white matter on T1-weighted and hyperintense on T2-weighted spin echo images. The T2-weighted gradient echo images showed a mixture of hypointense and hyperintense signal. This latter aspect has not previously been reported and is probably related to abundant intracellular deoxyhemoglobin in clotted areas rich in red blood cells.     

Curvilinear T1 hyperintense lesions representing cortical necrosis after cerebral infarction

Curvilinear T1 hyperintense lesions in the cerebral cortex in patients with subacute infarction were investigated for: (1) the presence or absence of T2* hypointensity and (2) correlations with neuropathologic findings. Thirty-six consecutive patients with subacute to chronic embolic infarction, in whom curvilinear hyperintense lesions in the infarcted cortex were seen on T1-weighted images, underwent echo-planar gradient-echo (GRE-EPI) T2*-weighted imaging. GRE-EPI T2*-weighted imaging revealed no evidence of hemorrhage within the curvilinear T1 hyperintense lesions of the cerebral cortex in all of the patients. In 11 of the 36 patients, focal hypointense lesions were seen in the depth of infarcted gyri on GRE-EPI T2*-weighted images. In the remaining 25 patients, no T2* hypointensities were seen in the infarct zone. Pathological correlation was performed in a patient with middle cerebral artery infarction and curvilinear hyperintense lesions on postmortem T1-weighted images. In the autopsied brain, curvilinear T1 hyperintense lesions corresponded to necrosis of all the cortical layers on histological examination. These data suggest that curvilinear hyperintense lesions in the cerebral cortex on T1-weighted images during the subacute to chronic period of cerebral infarction may not represent hemorrhage.     

Rathke cleft cysts: CT, MR imaging, and pathologic features

The authors retrospectively reviewed the clinical, computed tomography (CT), and magnetic resonance (MR) imaging findings in seven patients with pathologically proved Rathke cleft cysts. All the cysts were located in the anterior sella turcica or the anterior suprasellar cistern. Five cysts had both intra- and suprasellar components, one was entirely intrasellar, and the other was predominantly suprasellar in location. The size of the cysts ranged from 8 to 20 mm. CT scans demonstrated low-density homogeneous lesions in four cases. On MR images of three of these four cases, the cysts had the same intensity as cerebrospinal fluid on T1- and T2-weighted images, while in the fourth case, the cyst was hyperintense on the T1-weighted images. In the remaining three cases, CT showed slight hyperdensity relative to brain parenchyma, suggestive of contrast enhancement. MR showed signal heterogeneity of these lesions with focal components of diminished signal intensity of T2-weighted images. These same foci appeared iso- to slightly hyperintense on T1-weighted images.     

Vertex epidural hematomas: imaging findings and diagnostic pitfalls

PURPOSE: Our purpose was to show the computed tomography (CT) and magnetic resonance (MR) imaging features of vertex epidural hematomas (EDHs) and emphasize pitfalls in the diagnosis of this entity. SUBJECTS AND METHODS: The neuroradiologic studies of four patients (CT in four, MR imaging and MR venography in one) were evaluated for EDH shape, size and appearance. RESULTS: EDHs were biconvex in three patients and crescentic in one patient. CT appearances included a collection that was hyperdense (two patients), generally isodense with a few regions of hyperdensity (one patient) and mixed hyperdense and hypodense (one patient). MR imaging findings in one patient consisted of hyperintense signal on T1-weighted images and hypointense signal on T2-weighted images. Inferior displacement of the superior sagittal sinus was seen in two patients. Diagnosis of a small vertex EDH was difficult on routine axial CT in one patient, but apparent on MR imaging and MR venography. CONCLUSIONS: Small vertex EDHs can be difficult to diagnose on routine CT. MR imaging or thin section CT should be performed to exclude the diagnosis in patients with trauma to the skull vertex.     

Tongue abscesses: MR imaging findings

BACKGROUND AND PURPOSE: A lingual abscess is difficult to diagnose in the absence of physical signs. MR imaging may provide an excellent and invaluable adjunct to clinical examination, but the literature is incomplete in defining the various MR imaging findings of abscess. The objective of this study was to determine the MR imaging features of tongue abscesses. METHODS: Seven surgically proved tongue abscesses were evaluated with MR imaging. Four patients underwent MR imaging because of suspected tumor, and 3 patients, to show the extent and precise anatomic location of the lesion. Lesions were assessed with regard to the location, size, signal-intensity characteristics, and pattern of contrast enhancement. RESULTS: Five lesions were located in the anterior tongue and 2, in the posterior tongue. The central parts of 4 anterior tongue abscesses were hypointense, surrounded by a hyperintense wall on T1-weighted precontrast images. On postcontrast images, marked wall enhancement was detected. On T2-weighted images, a markedly hyperintense central part surrounded by a hypointense rim was seen. In 2 of these patients, there was a hypointense halo surrounding the wall (target sign). In 3 patients, a perilesional hyperintense area that enhanced diffusely after contrast administration was detected on T2-weighted images. The smallest lesion located in the anterior tongue was hypointense on T1-weighted images and enhanced diffusely on postcontrast images. On T2-weighted images, a markedly hyperintense central part surrounded by a mildly hyperintense peripheral part was depicted. Posterior tongue lesions appeared as polypoid ill-defined masses and were hypointense on T1-weighted images and heterogeneously hyperintense on T2-weighted images. On postcontrast images, the lesion in 1 patient showed diffuse and heterogeneous contrast enhancement, whereas the lesion in another patient enhanced peripherally. The lesions were totally excised in 4 patients and drained with surgical incisions in 3 patients. No recurrence was detected on follow-up. CONCLUSION: An abscess typically presents as a cystic lesion surrounded by an enhancing capsule formation, but lesions may also present as solid masses that enhance diffusely or peripherally.     

前列腺脓肿的MRI诊断

目的:探讨前列腺脓肿的MRI诊断价值。方法:回顾性分析4例临床证实的前列腺脓肿的MRI表现。结果:单个脓肿2例,多发脓肿2例。脓肿T1WI呈稍低信号或低信号,T2WI呈高信号或较高信号。增强扫描脓肿壁薄环状明显强化2例,厚环状中等度强化2例,内见强化分隔,脓腔不强化。伴精囊腺肿大3例,精囊腺脓肿1例。向前列腺周围组织蔓延2例。结论:前列腺脓肿MRI表现具有特征性,容易发现小脓肿,并可以确定脓肿蔓延的范围。