Differentiation of hepatic hemangiomas from metastases by dynamic contrast-enhanced MR imaging

Twenty-nine patients with hepatic hemangiomas (n = 14) and hepatic metastases (n = 15) underwent magnetic resonance (MR) imaging prior to and after an intravenous bolus injection of Gd-diethylenetriamine pentaacetic acid (0.2 mmol/kg). Before contrast application, a T2-weighted spin echo sequence (SE 1,600/105) and a T1-weighted gradient echo sequence (GE 315/14/90 degrees pulse angle) were performed. Beginning with injection of the contrast agent, a dynamic study was conducted for 10 min using a moderately T1-weighted gradient echo sequence (GE 40/14/40 degrees) with an acquisition time of 10.2 s per image. Delayed (11 min) and late (60 min) postcontrast images were obtained using a T1-weighted sequence (GE 315/14/90 degrees). In the dynamic study (0-10 min) the hemangiomas were characterized by peripheral contrast enhancement and a subsequent hyperintense fill-in. The metastases showed very mixed patterns of enhancement after contrast administration, and their signal intensity remained low compared with that of the hepatic tissue. In the delayed postcontrast examination (11 min) the hemangiomas had a very high and homogeneous signal intensity and the metastases were characterized by an inhomogeneous, hypointense to isointense signal. The contrast between tumor and liver [signal-difference-to-noise ratio (SD/N)] was higher for all hemangiomas than it was for the metastases. In the T2-weighted precontrast examination, on the other hand, five hemangiomas and seven metastases showed an overlap in the SD/N. The late postcontrast images (60 min) did not yield any further diagnostic information. We conclude that the combination of a dynamic MR study with delayed postcontrast T1-weighted imaging is a useful method of diagnosing hepatic hemangiomas.     

MR imaging for evaluation of severe facial nerve damage in patients with facial nerve palsy

PURPOSE: To evaluate the usefulness of MR imaging for the detection of severe facial nerve damage in patients with facial nerve palsy. MATERIALS AND METHODS: We retrospectively reviewed 26 consecutive patients with facial nerve palsy (13 non-responders and 13 responders). T1-weighted, T2-weighted, and postcontrast T1-weighted images were obtained in all patients. FLAIR images were also obtained in 3 non-responders. RESULTS: The geniculate ganglion, labyrinthine segment, and tympanic segment or mastoid segment showed high signal intensity on T2-weighted images in 9 of 13 non-responders, whereas high signal intensity of the nerve was only seen in 1 of 13 responders. FLAIR imaging revealed high signal intensity lesions of the distal intrameatal segment in 2 non-responders. Contrast enhancement of the facial nerve showed a similar pattern in non-responders and responders. High signal intensity lesions on T2-weighted or FLAIR images showed enhancement on postcontrast T1-weighted images. CONCLUSION: These results suggest that a high signal intensity area on T2-weighted images is a marker of severe facial nerve damage. FLAIR imaging is useful for identification of T2-prolongation in the distal intrameatal segment.     

Relationship between contrast enhancement on fluid-attenuated inversion recovery MR sequences and signal intensity on T2-weighted MR images: visual evaluation of brain tumors

PURPOSE: To investigate the relationship between the degree of contrast enhancement in fluid-attenuated inversion recovery (FLAIR) sequences and tumor signal intensity on T2-weighted images. MATERIALS AND METHODS: A total of 96 patients suspected of having brain tumors were examined by MR imaging, and whenever a brain tumor with an enhancing part larger than the slice thickness was demonstrated on postcontrast T1-weighted images, postcontrast FLAIR images were additionally acquired. The tumor signal intensity on the T2-weighted images was visually classified as follows: equal or lower compared with normal cerebral cortex (group 1), higher than normal cortex (group 2), and as high as cerebrospinal fluid (CSF) (group 3). When a lesion contained several parts with different signal intensities on T2-weighted images, we assessed each part separately. In each group, we visually compared pre- and postcontrast FLAIR images and assessed whether tumor contrast enhancement was present. When contrast enhancement was present on FLAIR sequence, the degree of contrast enhancement in T1-weighted and FLAIR sequences was visually compared. RESULTS: Postcontrast T1-weighted images showed 46 enhancing lesions, including 48 parts, in 31 MR examinations. FLAIR images of the lesion-parts in group 1 (N=18) did not show significant contrast enhancement. In group 2 (N=12), all the parts were enhanced in FLAIR sequences, and three parts were enhanced more clearly in the FLAIR sequences than in the T1-weighted sequences. In group 3 (N=18), all the parts were enhanced equally or more clearly in the FLAIR sequences than in the T1-weighted sequences. CONCLUSION: The signal intensity in FLAIR sequences is largely influenced by both T1 and T2 relaxation time; there is a close relationship between the signal intensity of brain tumors on T2-weighted images and the degree of contrast enhancement on FLAIR sequences. When tumors have higher signal intensity than normal cortex on T2-weighted images, additional postcontrast FLAIR imaging may improve their depiction.     

葡萄膜转移瘤的MRI表现

目的探讨葡萄膜转移瘤的MRI表现特点。方法回顾性分析20例经病理或临床随访证实的葡萄膜转移瘤的MRI表现。1例仅行平扫，19例同时行平扫和增强扫描，其中4例行动态增强扫描。结果20例葡萄膜转移瘤中，位于虹膜和睫状体2例，18例位于脉络膜；2例表现为略长T1、等T2信号，9例表现为等T1、等T2信号，3例表现为等T1、略长T2信号，3例表现为等T1、略短T2信号，2例表现为略短T1、略短T2信号，1例表现为略短T1、略长T2信号；8例表现为眼球壁轻度增厚，3例呈新月形，7例呈梭形，2例呈结节状。19例呈中度至明显强化；行动态增强扫描的4例时间-信号强度曲线均呈速升、缓降型。伴有视网膜脱离11例和玻璃体信号异常2例。结论MRI能显示葡萄膜转移瘤的部位、形态、信号及强化特点，有助于葡萄膜转移瘤的诊断与鉴别诊断。     

Brain: gadolinium-enhanced fast fluid-attenuated inversion-recovery MR imaging

PURPOSE: To determine the clinical utility of gadolinium-enhanced fluid-attenuated inversion-recovery (FLAIR) magnetic resonance (MR) imaging of the brain by comparing results with those at gadolinium-enhanced T1-weighted MR imaging with magnetization transfer (MT) saturation. MATERIALS AND METHODS: In 105 consecutive patients referred for gadolinium-enhanced brain imaging, FLAIR and T1-weighted MR imaging with MT saturation were performed before and after administration of gadopentetate dimeglumine (0.1 mmol per kilogram of body weight). Pre- and postcontrast images were evaluated to determine the presence of abnormal contrast enhancement and whether enhancement was more conspicuous with the FLAIR or T1-weighted sequences. RESULTS: Thirty-nine studies showed intracranial contrast enhancement. Postcontrast T1-weighted images with MT saturation showed superior enhancement in 14 studies, whereas postcontrast fast FLAIR images showed superior enhancement in 15 studies. Four cases demonstrated approximately equal contrast enhancement with both sequences. Six cases showed some areas of enhancement better with T1-weighted imaging with MT saturation and other areas better with postcontrast fast FLAIR imaging. Superficial enhancement was typically better seen with postcontrast fast FLAIR imaging. CONCLUSION: Fast FLAIR images have noticeable T1 contrast making gadolinium-induced enhancement visible. Gadolinium enhancement in lesions that are hyperintense on precontrast FLAIR images, such as intraparenchymal tumors, may be better seen on T1-weighted images than on postcontrast fast FLAIR images. However, postcontrast fast FLAIR images may be useful for detecting superficial abnormalities, such as meningeal disease, because they do not demonstrate contrast enhancement of vessels with slow flow as do T1-weighted images.     

Delayed MR imaging of hepatocellular carcinoma enhanced by gadobenate dimeglumine (Gd-BOPTA).

The purpose of this study was to determine the efficacy of gadobenate dimeglumine (Gd-BOPTA)-enhanced magnetic resonance (MR) imaging for evaluation of hepatocellular carcinoma HCC. MR images were obtained in 14 patients with 31 HCC nodules as a part of a phase III clinical trial. T1- and T2-weighted images were obtained before and after iv administration of 0.1 mmol/kg of Gd-BOPTA. Two blinded readers evaluated pre- and delayed postcontrast images separately for detection of tumor nodules. Quantitative measurements of signal-to-noise (SNR) and tumor/liver contrast-to-noise (CNR) ratios were also performed. A signal/intensity ratio was calculated. Tumor enhancement was correlated with histologic findings. Consensus agreement of precontrast T1- and T2-weighted images revealed 23/31 HCC nodules in 14 patients; postcontrast T1-weighted images demonstrated 24/31 HCC nodules in the same number of patients. Combining both pre- and postcontrast images, 27/31 lesions were detected. Four patients had four well-differentiated HCC nodules detected only on postcontrast images, while three well-differentiated lesions in two patients were only seen on precontrast images. Quantitative evaluation showed an SNR ratio increase in both liver parenchyma and HCC nodules, as well as a significant increase in the absolute CNR ratio on postcontrast T1-weighted gradient-recalled images (P < 0.05). Well-differentiated HCC lesions showed a greater enhancement than poorly differentiated HCC lesions.     

Chondromyxoid fibroma of the frontal bone.

Chondromyxoid fibroma of frontal bone is a rare lesion. Plain skull films showed a round radiolucent mass with a sclerotic margin. It was dense on plain CT scan and showed no convincing contrast enhancement. MR imaging showed low signal intensity relative to gray matter on T1-weighted image (500/20), isointensity on proton-density image (2000/30), high intensity on T2-weighted image, and marked peripheral enhancement on postcontrast (gadopentetate dimeglumine) study.     

Optimizing brain MR imaging protocols with gadopentetate dimeglumine: enhancement of intracranial lesions on spin-density- and T2-weighted images

To determine whether long TR MR imaging is best performed before or after IV administration of gadopentetate dimeglumine, we obtained spin-density- and T2-weighted images before and after contrast administration in 21 patients with known intracranial enhancing lesions. Of 25 lesions demonstrating enhancement on T1-weighted sequences, 21 showed mild or moderate enhancement on spin-density-weighted sequences and 20 showed mild enhancement on T2-weighted sequences. Importantly, no spin-density or T2 information was obscured by the administration of gadopentetate dimeglumine, and no T2 shortening effects were visible. Two new foci of enhancement were visible on postcontrast spin-density- and T2-weighted images that were missed on postcontrast T1-weighted images and on precontrast spin-density- and T2-weighted studies. Visualization of new areas of enhancement is the main advantage provided by the long TR images obtained after IV injection of gadopentetate dimeglumine. The most likely reason for the appearance of these newly visualized lesions is thought to be delayed enhancement. This imaging protocol also allows the display of adjacent edema or gliosis and enhancing lesions on a single image. Additionally, in three cases, posterior fossa phase-shift artifacts raised the suspicion of an enhancing lesion on postcontrast T1-weighted images, but the cerebellum was shown to be normal on the postcontrast spin-density- and T2-weighted studies. On the basis of our results, we recommend obtaining long TR images after rather than before the administration of gadopentetate dimeglumine in patients with intracranial enhancing lesions.     

Improved detection of enhancing and nonenhancing lesions of multiple sclerosis with magnetization transfer.

PURPOSETo determine whether magnetization transfer imaging can improve visibility of contrast enhancement of multiple sclerosis plaques.METHODSFifty-nine enhancing and 63 nonenhancing lesions in 10 patients with multiple sclerosis were evaluated to calculate contrast-to-noise ratios on conventional T1-weighted and T1-weighted magnetization transfer images. The signal intensity of the lesion and the background (white matter) were measured on precontrast T1-weighted and T1-weighted magnetization transfer images (800/20/1 [repetition time/echo time/excitations]) and on postcontrast T1-weighted and T1-weighted magnetization transfer images. Mean contrast-to-noise ratios was calculated for all lesions.RESULTSThe contrast-to-noise ratio was significantly higher for enhancing and nonenhancing lesions on T1-weighted magnetization transfer images than on conventional T1-weighted images. For enhancing lesions, the contrast-to-noise ratio was significantly higher on postcontrast T1-weighted magnetization transfer images, 32 +/- 2 compared with 21 +/- 2 on conventional T1-weighted images. Fifty of the 59 enhancing lesions were seen on both the T1-weighted and the T1-weighted magnetization transfer images. Nine enhancing lesions were seen only on the postcontrast T1-weighted magnetization transfer images. In addition, of 63 nonenhancing lesions seen on proton-density, T2-weighted, and T1-weighted magnetization transfer images, 16 were not seen on the conventional T1-weighted images. Seven of the 63 nonenhancing lesions and 7 of the 59 enhancing lesions had high signal intensity on the precontrast T1-weighted magnetization transfer images suggestive of lipid signal, a finding not seen on the conventional precontrast T1-weighted images.CONCLUSIONMagnetization transfer improves the visibility of enhancing multiple sclerosis lesions, because they have a higher contrast-to-noise ratio than conventional postcontrast T1-weighted images. High signal intensity on both nonenhancing and enhancing lesions noted only on precontrast T1-weighted magnetization transfer suggests a lipid signal was unmasked. If magnetization transfer is used in multiple sclerosis patients, a precontrast magnetization transfer image is necessary.     

Different signal intensities between intra- and extracranial components in jugular foramen meningioma: an enigma

BACKGROUND AND PURPOSE: The purpose of this study was to evaluate retrospectively differences in MR signal intensity and contrast enhancement between intra- and extracranial components of jugular foramen meningioma (JFM). METHODS: MR studies of eight patients who underwent surgery for histologically confirmed JFM were reviewed retrospectively. Signal intensity differences between intra- and extracranial components of all eight JFMs on axial T1-, T2-, and postcontrast T1-weighted images were evaluated visually. In six of the eight JFMs, quantitative signal intensity evaluations were also performed by using relative signal intensity ratios of the intra- and extracranial components of JFM to CNS tissue at the same level. Paired t tests were used to evaluate differences in relative signal intensity ratios in each JFM between intra- and extracranial components. RESULTS: Both visual and quantitative signal intensity evaluations revealed that signal intensities of the intracranial component of JFM were significantly higher than those of the extracranial component on T1-, T2-, and postcontrast T1-weighted images. Results of relative signal intensity ratios were 0.89 +/- 0.04 versus 0.77 +/- 0.02 on T1-weighted images (P = .002); 1.66 +/- 0.28 versus 0.88 +/- 0.14 on T2-weighted images (P = .003); and 2.16 +/- 0.29 versus 1.77 +/- 0.26 on postcontrast T1-weighted images (P = .01). CONCLUSION: Intra- and extracranial components of JFM display different signal intensity and enhancement patterns. These differences may be related to histologic composition, and in particular, collagen content.     

Contrast-enhanced magnetization transfer MR of the brain: importance of precontrast images.

PURPOSETo determine the importance of obtaining precontrast T1-weighted magnetization transfer (MT) MR images for better interpretation contrast-enhanced T1-weighted MT images.METHODSOne hundred fifty-five patients referred for MR imaging of the brain were examined prospectively with noncontrast T1-weighted imaging, noncontrast T1-weighted imaging with MT, contrast-enhanced T1-weighted imaging, and contrast-enhanced T1-weighted imaging with MT. In the patients who had abnormally increased signal intensity on postcontrast images (with or without MT), the four imaging sequences were evaluated with regard to number of lesions and lesional signal intensity. For each of the sequences, two experienced neuroradiologists subjectively graded the lesions on a scale of 1 to 4 (4 being the most conspicuous) with regard to abnormally increased signal intensity.RESULTSTwenty-two of the 155 patients had increased signal intensity on one or more of the postcontrast sequences. Eight of these 22 patients had increased signal intensity of one or more lesions on images without MT. All these lesions were seen better on images obtained with MT. An additional six of the 22 patients had increased signal intensity of one or more lesions on images obtained with MT that was not detected on images obtained without MT. Eight of the 22 patients had no high signal intensity on noncontrast images with or without MT. One of the eight had increased number and conspicuity of lesions on postcontrast MT images.CONCLUSIONSA significant number of patients had increased signal intensity on noncontrast T1-weighted images with MT that was not seen on noncontrast T1-weighted images without MT. This high signal intensity was also visible on postcontrast MT images, and would have been mistaken for pathologic enhancement if noncontrast MT images had not been available for comparison.     

Cerebral ischemia: evaluation with contrast-enhanced MR imaging

Eighty patients with a total of 82 ischemic lesions were examined with contrast-enhanced MR imaging 1 hr to 1 month after onset of symptoms. The studies were reviewed retrospectively to determine the presence of arterial enhancement and the patterns of parenchymal enhancement. Arterial enhancement was often detected on the initial MR examination (45%), was frequently demonstrated in cortical infarction (86%), in some cases preceded the development of signal changes on T2-weighted images, and resolved by 11 days. The presence of arterial enhancement appeared to be a better indicator of clinical severity than was the presence of proximal vessel occlusion on MR or angiographic studies. Two patterns of parenchymal enhancement were seen: progressive enhancement and early and/or intense enhancement. In patients with the progressive pattern, parenchymal enhancement on postcontrast T1-weighted images was rarely seen before 7 days, while signal abnormalities on T2-weighted images were intense during the first few days. The early and/or intense enhancement pattern was usually present within the first 3 days, approximated or exceeded the area and intensity of signal changes on T2-weighted images, and was usually associated with minimal or reversible neurologic sequelae (except when located in or near a watershed zone), suggesting a lesser degree of ischemic insult than was associated with the progressive pattern.(ABSTRACT TRUNCATED AT 250 WORDS)     

Wernicke encephalopathy: MR findings and clinical presentation

Wernicke encephalopathy (WE) is a severe neurological disorder caused by vitamin B1 deficiency. The aim of the study was to analyse MRI findings typical for this disease and to evaluate the significance of their correlations with clinical symptoms. Magnetic resonance images and clinical features of 12 patients with WE were analysed. The patients underwent MR imaging within 3–14 days after onset of clinical symptoms. In 7 of 12 patients MR imaging showed symmetrical diencephalic and midbrain lesions. Postcontrast T1-weighted images from 5 of 9 patients examined during the initial 6 days of acute WE showed a subtle enhancement of the mamillary bodies, the tectal plate, the periaqueductal area and the periventricular region of the third ventricle including the paramedian thalamic nuclei. In addition, T2-weighted and fluid-attenuated inversion recovery (FLAIR) images revealed hyperintense signals in these regions (except for 2 patients where the mamillary bodies were normal). Hyperintense lesions on T2-weighted images without any enhancement on postcontrast T1-weighted images were detected in 2 patients by MR imaging performed 11 or 14 days after onset of WE. Patients with hyperintensities on T2-weighted images of the periventricular region of the third ventricle and the paramedian thalamic nuclei had poor recovery from their mental dysfunction. The MR examination in case of WE shows a typical pattern of lesions in 58% of cases. Enhancement of the mamillary bodies, the periventricular region of the third ventricle including the paramedian thalamic nuclei, and the periaqueductal area on postcontrast T1-weighted images can be observed in the initial period after clinical onset of symptoms and are characteristic signs of the acute stage of WE. Hyperintense lesions in the periventricular region and the paramedian thalamic nuclei on T2-weighted and FLAIR images in the subacute stage of WE and enhancement on postcontrast T1-weighted images of the mamillary bodies and the paramedian thalamic nuclei are indicators of poor prognosis despite vitamin B1 substitution. Electronic Publication     

MR imaging of orbital mass lesions with contrast agent: A preliminary report

To investigate the advantage and limit of contrast enhancement in the examination of orbital mass lesions, precontrast T1- and T2-weighted, and postcontrast T1-weighted spin-echo images were retrospectively compared by two experienced observers. Using contrast material, intraocular tumors were well detected and characterized, and several orbital tumors were characterized as to whether cystic or necrotic and intracranial involvement was better evaluated. On the other hand, tumor-fat interface lost conspicuity when tumors showed enhancement. We conclude that gadopentetate-dimeglumine-administered T1-weighted images were helpful in detecting, differentiating and characterizing tumors of the orbit. However, the loss of contrast with fatty tissue is a disadvantage to be considered.     

Debris-filled biliary system: a difficult diagnosis on MRI and MRCP

We describe a debris-filled biliary system as a difficult diagnosis using magnetic resonance imaging and magnetic resonance cholangiopancreatography (MRCP). A male patient aged 60 years showed a nonvisualized biliary system due to complete filling with debris. The following imaging features were observed: mild heterogeneity of intermediate signal on T2-weighted, MRCP and T1-weighted images and mild heterogeneous enhancement of periportal tissue on early and late postcontrast images. The absence of simple-appearing bile on T2 or MRCP images made the diagnosis of dilated, debris-filled biliary system challenging.     

脉络膜血管瘤的MRI表现及动态增强研究

目的 探讨眼脉络膜血管瘤的常规及动态增强MRI表现.方法 回顾性分析30例(31只眼共32个病灶)经临床、眼底相及荧光血管造影确诊的脉络膜血管瘤的MRI资料,其中行平扫和常规增强扫描30例,行动态增强扫描26例,观察各个序列MRI表现,计算动态增强曲线参数.结果 32个脉络膜血管瘤病灶中,位于视乳头颞侧26个病灶,呈梭形28个病灶;与玻璃体信号相比,T1WI呈等信号23个病灶,T2研呈等信号31个病灶;增强后明显强化32个病灶,强化均匀31个病灶,不均匀1个病灶,伴视网膜脱离18只眼;动态增强扫描出现填充征12个病灶,时间-信号曲线呈速升缓降型28个病灶,峰值时问为(91.00±25.27)s,上升斜率为3.03±1.13,流出率中位数为17.06%,强化率为2.87±0.79.结论 脉络膜血管瘤MRI现病灶形态、信号及动态增强具有一定特点,能为临床诊断和治疗方案制定提供重要信息.     

脊髓结核瘤的MR I表现分析并文献复习

目的：分析脊髓结核瘤的 MRI表现并文献复习。方法回顾性分析5例经临床和影像证实的脊髓结核瘤患者 MRI表现,所有患者MRI检查包括T1 WI、T2 WI平扫和T1 WI增强扫描,观察病变的部位、信号特点、强化方式和形态。结果1例病变位于颈段脊髓,为稍长T1、短T2信号,呈结节样强化;3例病变位于下胸段脊髓,横断位T2 WI表现为典型的“靶征”,增强后呈环状强化,矢状位其长轴与脊髓长轴一致,其中1例增强后发现合并1个平扫不能显示的粟粒强化结节;1例病变位于脊髓圆锥,为长 T1、短T2信号,增强后呈环状强化。结论脊髓结核瘤 MRI表现具有多样性,其特征性表现包括 T2 WI 低信号或“靶征”、环状强化、病变长轴与脊髓长轴一致。     

Exercise-induced acute renal failure and patchy renal vasoconstriction: CT and MR findings

Contrast-enhanced CT and MR imaging of the kidney were performed in two patients with acute renal failure and severe loin pain following a track race. Prior to the exercise both patients had had flu-like symptoms and took oral medications. There was no evidence of myoglobinuria. Immediate postcontrast CT of the kidney showed multiple patchy areas of poor contrast enhancement; after 24 h, there were multiple patchy enhancing cortical areas on CT without further use of intravenous contrast media. Magnetic resonance imaging of the kidney showed patchy areas of high signal intensity with obliteration of the corticomedullary contrast on T1-weighted images. On T2-weighted images the signal intensity of the lesion was high in one patient and low in the other.     

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.     

Marginal erosive discovertebral ”Romanus” lesions in ankylosing spondylitis demonstrated by contrast enhanced Gd-DTPA magnetic resonance imaging

Objective. To assess the value of Gd-DTPA magnetic resonance (MR) imaging in the demonstration of marginal destructive discovertebral Romanus lesions in ankylosing spondylitis. Design and patients. A prospective study of Gd-DTPA MR imaging was performed in 39 patients with a clinical diagnosis of ankylosing spondylitis and typical Romanus lesions seen on radiographs of the thoracolumbar spine. MR morphological appearances and signal intensity changes at the discovertebral junctions were analysed and compared with the radiographic findings. Results. Ninety-nine discovertebral junctions with Romanus lesions showed low signal intensity on T1-weighted and high signal on T2-weighted and T1-weighted postcontrast images at the vertebral corners consistent with oedematous hyperaemic inflammatory tissue. There were nine discovertebral junctions with similar MR findings but normal radiographs. Fifty-three discovertebral junctions showed syndesmophyte formation with increased signal intensity on both T1- and T2-weighted images with no contrast enhancement. Sixty-five discovertebral junctions showed a mixture of radiographic features and varied high and low signal changes at the vertebral rim on MR imaging with rims of enhancement in the vertebral body following contrast administration. Conclusion. Gd-DTPA MR imaging demonstrates a variable signal pattern and degree of contrast enhancement which may reflect the evolutionary stages of discovertebral enthesitis in ankylosing spondylitis. MR imaging may identify early erosive changes in radiographically normal vertebra. The role of MR imaging needs further investigation. Received: 6 April 1998 Revision requested: 7 May 1998 Revision received: 26 October 1999 Accepted: 27 October 1999