Small hepatocellular carcinomas in cirrhosis: differences in contrast enhancement effects between helical CT and MR imaging during multiphasic dynamic imaging

PURPOSE: The purpose of this study was to evaluate differences in the degrees of contrast enhancement effects of small hepatocellular carcinomas (HCCs) in patients with cirrhosis between helical computed tomography (CT) and magnetic resonance (MR) imaging during multiphasic contrast-enhanced dynamic imaging and to determine the diagnostic value of MR imaging especially in assessing hypovascular HCCs detected as hypoattenuating nodules on late-phase CT. SUBJECTS AND METHODS: This study included 64 small HCCs (<3 cm in diameter) in 40 patients with chronic hepatitis or cirrhosis who underwent multiphasic (arterial, portal and late phases) contrast-enhanced dynamic helical CT and MR imaging. The contrast enhancement patterns of each lesion in the arterial and late phases were evaluated by two radiologists experienced in liver MR imaging and categorized as one of five grades (1=hypoattenuated/hypointense; 2=slightly hypoattenuated/hypointense; 3=isoattenuated/isointense; 4=slightly hyperattenuated/hyperintense; 5=hyperattenuated/hyperintense), compared with the surrounding liver parenchyma. RESULT: Forty-three (67%) of 64 lesions showed Grade 4 (n=24) or Grade 5 (n=19) enhancement on arterial-phase CT, while 51 (80%) of 64 lesions showed Grade 4 (n=20) or Grade 5 (n=31) enhancement on arterial-phase MR imaging, indicating hypervascular HCCs. The grading score of hypervascular HCCs on arterial-phase MR imaging (mean: 4.61) was significantly (P<.01) higher than that for hypervascular HCCs on arterial-phase CT (mean: 4.20), showing better detection of the hypervascularity (arterial enhancement) of the lesion on arterial-phase MR imaging. Regarding hypovascular HCCs, all (100%) of 21 hypovascular HCCs on CT showed Grade 1 (n=10) or Grade 2 (n=11) enhancement on late-phase CT, seen as hypoattenuation. In contrast, 8 (62%) of 13 hypovascular HCCs on MR imaging showed Grade 1 (n=1) or Grade 2 (n=7) enhancement on late-phase MR imaging, seen as hypointensity. Grading scores of hypovascular HCCs on late-phase images were significantly (P<.001) lower on CT than on MR imaging (mean score: 1.52 vs. 2.31), indicating better washout effects for hypovascular HCCs on late-phase CT. CONCLUSION: The washout effects for small HCCs on late-phase MR imaging were inferior to those for small HCCs on late-phase CT. Especially, hypovascular HCCs demonstrated as hypoattenuating nodules on late-phase CT were often not seen on late-phase MR imaging, requiring careful evaluation of other sequences, including unenhanced T(1)-weighted and T(2)-weighted MR images.     

采用氧合血红蛋白吸收带的漫反射光谱比率R540/R575检测人胃癌

采用氧合血红蛋白吸收带的平均漫反射光谱比率(R540/R575)对离体的人正常胃、未分化胃腺癌、胃鳞状细胞癌和低分化胃腺癌的上皮粘膜组织进行鉴别诊断.实验采用带积分球附件的分光光度计测量组织样品在400 nm～600 nm的漫反射光谱.实验结果表明,在相同的波长范围内,人的未分化胃腺癌、胃鳞状细胞癌和低分化胃腺癌的上皮粘膜组织的漫反射光的强度较人正常胃的上皮粘膜组织的漫反射光强度要显著地低的,尤其是在氧合血红蛋白的吸收带540 nm和575 nm波长处,人正常胃、未分化胃腺癌、胃鳞状细胞癌和低分化胃腺癌的上皮粘膜组织的平均漫反射光谱比率分别是(94.25±2.4)%,(109±3.0)%,(1032±2.8)%和(98.6±2.6)%.     

(1)H-MRS metabolic patterns for distinguishing between meningiomas and other brain tumors

Yet meningiomas have characteristic neuroimaging features, some other lesions are still confusing with meningiomas. The aim of this study was trying to find the typical (1)H-MRS metabolic factors of histologic subtyped meningiomas, schwannomas, metastases, and other brain tumors for differential diagnosis among them. (1)H-MRS using STEAM (TE/30 ms, TR/2 sec) and PRESS (TE/288 ms, TR/2 sec) sequences were performed on 44 untreated brain tumors. Obtained metabolic patterns from the typical spectra of meningioma, schwannoma, metastasis were compared with each other or other brain tumors to evaluate the usefulness for diagnosis between them. Alanine(Ala) was observed in 15 cases of the 19 meningiomas with a little variation to three histologic subtypes, while minimal lipids were observed in every 19 meningiomas. Elevated glutamate/glutamine(Glx) was detected in 12 cases of the meniningiomas. Increased myo-inositol(mI) was detected in 11 cases of the 13 schwannomas. Dominant lipids signals as well as long-T2 lipids were detected in every metastasis in conjunction with elevated choline (Cho). Enhanced Glx was observed in 4 cases of the 8 metastases without correlation of primary tumor site or types. Hemangiopericytoma showed different spectral patterns from typical meningiomas: only dominant Cho, minimal lipids and absence of Ala or Glx signals. These metabolic patterns in typical tumors may provide a basis for differential diagnosis (average value of chi(2) = 23.33, p < 0.01) between meningiomas and schwannomas as well as metastases. However proton spectral distinction among the different histologic subtypes of meningiomas was not definite.     

Metastatic Gastric Leiomyoblastoma: A Case Report

Gastric leiomyoblastoma is a rare entity. In this report, we describe the magnetic resonance (MR) appearance of a recurrent gastric leiomyoblastoma 14 years after initial presentation. This tumor was heterogeneous and moderately low signal intensity on T₁-weighted images and heterogeneous and moderately high signal intensity on T₂-weighted images. The tumor also contained foci of low signal intensity on the post gadolinium images, consistent with areas of necrosis. The mass enhanced mildly and increased in enhancement on the delayed images, consistent with a hypovascular mass. Multiple liver metastases were noted. Magnetic resonance findings were confirmed with surgical specimens.     

Diffusion Tensor Magnetic Resonance Imaging in Ring-Enhancing Cerebral Lesions

The objective of this study is to determine differential diagnostic value of diffusion tensor imaging (DTI) in high-grade brain astrocytomas, brain solitary metastases and brain abscesses. 53 patients with cerebral solitary lesions which showed ring enhancement on contrast-enhanced T ₁-weighted images were enrolled in this study. Brain tissues were examined pathologically from 49 patients to confirm the cerebral occupational diseases. Four patients have been diagnosed with primary cancer plus brain solitary metastasis. DTI measurements were obtained from regions of interest placed on central cavity, white matter of the immediate peritumoral region (IPR) and cerebral white matter of the normal side. The cavity of high-grade astrocytoma and brain metastases displayed hypointense signals; most of the brain abscess cavities displayed high signal intensity except for one case with uneven signal intensity. Mean diffusivity (MD) and fractional anisotropy (FA) values could be used for differentiation between tumor and abscess in brain. The brain abscess cavities showed restricted diffusion and anisotropy [MD = (0.604 ± 0.13) × 10⁻³ mm²/s, FA = 0.185 ± 0.03], whereas the central portion of high-grade astrocytoma [MD = (2.76 ± 0.26) × 10⁻³ mm²/s, FA = 0.069 ± 0.02] and solitary brain metastases [MD = (2.82 ± 0.29) × 10⁻³ mm²/s, FA = 0.064 ± 0.02] showed unrestricted diffusion and isotropy. Brain abscess could be differentiated by MD and FA values in their cavities from brain tumors (P < 0.01). The IPRs were all depicted as hyperintense or isointense signals on diffusion-weighted imaging. The difference between FA values in the IPR of high-grade brain astrocytomas and other groups was statistically significant (P < 0.01). In conclusion, our results suggested the potential role of the cavity MD and FA values in the differential diagnoses of brain tumors and brain abscesses; meanwhile, high-grade astrocytomas could be distinguished from solitary metastases and abscesses by evaluating their corresponding FA values in the IPR on brain magnetic resonance imaging (MRI). Combined with conventional MRI, DTI may help radiologists to facilitate the differential diagnosis of ring-enhancing cerebral lesions in clinical practice.     

Sequential use of gadolinium chelate and mangafodipir trisodium for the assessment of focal liver lesions: initial observations

The purpose of this study was to assess the feasibility of sequential administration of 2 different MR imaging contrast agents using a single visit protocol to image focal liver abnormalities. Twenty-one patients with known or suspected liver lesions were included in the study. All patients received a bolus intravenous injection of gadolinium chelate (Gd) and dynamically enhanced imaging performed. The patients then received an injection of mangafodipir trisodium (Mn) contrast and a second scan performed with an average delay of 62 min after the Gd bolus injection. The images were evaluated to determine the appearance of liver lesions after administration of each contrast agent, and for evidence of prior Gd administration adversely affecting evaluation of images acquired after Mn administration. Focal liver lesions were present in 19 patients, including 8 with liver metastases, 1 with liver lymphoma, 6 with hemangiomas, 3 with focal nodular hyperplasia (FNH), and 1 with hepatic abscess. In 2 other patients no liver lesions were identified in either the post-Gd or post-Gd-post-Mn scans. All malignant lesions identified on the post-Gd scan were also identified on post-Gd-post-Mn scans. Although the potential benefit for increasing detection sensitivity for hepatic metastases was not demonstrated, this is a preliminary series. This study does demonstrate the practicality for use a single visit sequential Gd-Mn protocol described here, with possible application of this technique for further assessment of the utility of combining Gd and Mn for detection of liver metastases.     

Optimizing brain MRI protocols in the follow-up of patients with multiple sclerosis T2-weighted MRI of the brain after the administration of gadopentetate dimeglumine

The aim of our study was to determine whether T2-weighted (T2w) MRI of the brain could be performed immediately after the administration of gadopentetate dimeglumine (gadolinium DTPA) in patients with multiple sclerosis (MS) without a loss in image quality or diagnostic reliability. Sixteen patients with clinically diagnosed MS were included in the study. Twenty-four patients with various cerebral pathologies (14 patients with multiple lacunar lesions) were examined in order to exclude masking of T2 hyperintense lesions other than MS lesions. Images of 10 patients without pathological changes served as a control condition for the qualitative analysis. In these 50 patients, T1w and T2w MRI was performed before and after the administration of gadolinium DTPA. Signal intensities were measured within T2 hyperintense cerebral lesions, in T1-enhancing lesions and in normal appearing brain tissue on T2w turbo spin-echo (TSE) sequences. Both quantitative and qualitative analysis did not show significant differences between T2w pre- and postcontrast series. T2w MRI performed prior to and after the administration of gadolinium DTPA provides similar information in patients with MS. With a TR of 3.2 s, not a single lesion was obscured on T2w postcontrast series. Acquisition of T2w MR images immediately after the administration of gadolinium DTPA allows for shorter examination time and assures sufficient time for contrast enhancement in cerebral lesions with a disrupted blood-brain barrier.     

Cystic intracranial mass lesions: Possible role of in vivo MR spectroscopy in its differential diagnosis

Thirty-four patients showing cystic intracranial mass lesions on MR imaging were evaluated by in vivo proton MR spectroscopy (MRS) with the aim of detecting lesion-specific spectral patterns that may assist imaging in better tissue characterization. In vivo spectroscopy was performed using stimulated echo acquisition mode with echo times 20 m and 270 m in all, and spin echo with echo time 135 m in 11 patients. All primary neoplasms (intra-as well as extra-axial) showed choline (3.22 ppm) resonance along with lipid and/or lactate (1.3 ppm). It was not possible to grade cystic gliomas based on N-acetyl asparate-to-choline ratio. High-grade gliomas (n = 8) showed lipid/lactate and low-grade gliomas (n = 6) showed only lactate. Seven patients with brain abscess showed resonances only from acetate (1.92 ppm), lactate (1.3 ppm) and alanine (1.5 ppm). Two cases of metastatic adenocarcinoma showed only lipid/lactate. In 7 patients with epidermoid cyst, lactate along with an unassigned resonance at 1.8 ppm was observed and could be easily differentiated from arachnoid cyst (n = 2), which showed only minimal lactate. A case of cystic meningioma could be differentiated from cystic schowannoma by the presence of alanine in the former. It is concluded that MR imaging, when combined with in vivo MRS, may help to better characterize intracranial cystic mass lesions.     

Comparison of gadolinium chelates with manganese-DPDP for liver lesion detection and characterization: Preliminary results

Nonspecific extracellular gadolinium chelate (NEGd) was prospectively compared with manganese (Mn)-DPDP (Mn) for the detection and characterization of focal liver lesions of various histology. Seventeen patients with known or suspected focal liver lesions underwent NEGd and Mn-enhanced studies at 1.5 T. Study findings were correlated with histology (five patients), computed tomography (CT) examinations (17 patients), and 4- to 13-month imaging follow-up by CT and/or MR (five patients). NEGd studies were performed as serial postcontrast spoiled gradient echo (SGE) sequences, and Mn studies were performed as SGE sequences 15 and 30 min postcontrast and T₁-weighted, fat-suppressed spin echo at 16 min. NEGd and Mn images were prospectively interpreted in a separate blinded fashion. Lesion detection and characterization were determined. NEGd and Mn-enhanced images demonstrated 61 and 49 lesions, respectively (p = .1, NS). A total of 60 and 33 lesions were characterized on NEGd and Mn images, respectively, which was significantly different (p = .008). No differences were observed for the detection and characterization of liver metastases; whereas there was a trend for superior detection and characterization for hepatocellular carcinoma with NEGA.     

Oxygenated hemoglobin diffuse reflectance ratio for in vitro detection of human gastric pre-cancer

Oxygenated hemoglobin diffuse reflectance (DR) ratio (R540/R575) method based on DR spectral signatures is used for early diagnosis of malignant lesions of human gastric epithelial tissues in vitro. The DR spectra for four different kinds of gastric epithelial tissues were measured using a spectrometer with an integrating sphere detector in the spectral range from 400 to 650 nm. The results of measurement showed that the average DR spectral intensity for the epithelial tissues of normal stomach is higher than that for the epithelial tissues of chronic and malignant stomach and that for the epithelial tissues of chronic gastric ulcer is higher than that for the epithelial tissues of malignant stomach. The average DR spectra for four different kinds of gastric epithelial tissues show dips at 542 and 577 nm owing to absorption from oxygenated Hemoglobin (HbO₂). The differences in the mean R540/R575 ratios of HbO₂ bands are 6.84% between the epithelial tissues of normal stomach and chronic gastric ulcer, 14.7% between the epithelial tissues of normal stomach and poorly differentiated gastric adenocarcinoma and 22.6% between the epithelial tissues of normal stomach and undifferentiated gastric adenocarcinoma. It is evident from results that there were significant differences in the mean R540/R575 ratios of HbO₂ bands for four different kinds of gastric epithelial tissues in vitro (P < 0.01).     

MRI findings of gastric metastases from breast carcinoma

We describe the MR appearance of breast cancer metastases to the stomach. The stomach wall was diffusely thickened with loss of the regular fold pattern best shown on the single shot T2-weighted images and enhanced with moderate mural enhancement on early and late post gadolinium images. The combination of gastric wall thickening and abnormal enhancement should suggest the diagnosis of diffuse mural metastases in a woman with a history of breast cancer.     

Peliosis hepatis and neoplastic/dysplastic lesions in aged male Long-Evans Cinnamon rats: MR imaging with pathologic correlation

The Long-Evans Cinnamon (LEC) rat, an animal model of Wilson's disease, abnormally accumulates copper in the liver. There have been a lot of reports on preneoplastic and neoplastic hepatic tumors in LEC rats, but few studies have been focused on other lesions. The aim of this study was to describe the MR findings of the liver of LEC rats with pathologic correlation to characterize the hepatic lesions developed in them. We measured MR images of the liver of six aged (over the age of 70 weeks old) male LEC rats. Measurements of T(1), T(2)-weighted images, and the dynamic and delayed studies after i.v. gadolinium injection were performed. The rats were sacrificed immediately after the measurements, and the diagnosis was histologically made. We identified seven lesions of peliosis hepatis, three neoplastic/dysplastic lesions, three cysts and one cholangiofibrosis. Peliosis hepatis was characterized as showing a significantly long T(2) relaxation time of 57.9 +/- 13.3 ms (mean +/- standard deviation) compared with 41.3 +/- 1.7 ms in normal liver, and prolonged enhancement after a gadolinium injection. Neoplastic/dysplastic lesions tended to show prolonged T(2), and they showed isointensity on T(1)-weighted images. They were best characterized by early enhancement followed by a rapid wash-out after a gadolinium injection. In conclusions, the frequent occurrence of peliosis hepatis observed in the present study suggests this can be a characteristic lesion in aged LEC rats. The characteristic MR findings enable us to distinguish between peliosis hepatis and neoplastic/dysplastic lesions.     

Is gadoxetic acid-enhanced MRI limited in tumor characterization for patients with chronic liver disease?

Purpose

There are pros and cons to the use of gadoxetic acid in hepatocellular carcinoma (HCC) workup due to the potential for high false positive diagnosis. This study was conducted to investigate the preoperative diagnostic performance of gadoxetic acid-enhanced MRI protocol including diffusion-weighted imaging (DWI) with emphasis on tumor characterization developed in high risk HCC patients.

Materials and methods

We included 144 patients (102 men, 42 women; age range 33–74 years) with chronic viral hepatitis or cirrhosis and 183 focal hepatic tumors (size range, 0.4–11.0 cm; mean, 3.2 cm), including 148 HCCs, 13 cholangiocarcinomas, 12 hemangiomas, three hepatocellular adenomas, two focal nodular hyperplasias, and five other tumors. All patients underwent gadoxetic acid-enhanced MRI protocol with DWI. MRIs were independently interpreted by three observers for the detection and characterization of hepatic tumors.

Results

Sensitivities for detecting all 183 liver tumors were 98.4%, 97.8%, and 96.2% for each observer, respectively, with a 97.5% for pooled data. Among 183 hepatic tumors, 91.3% (n = 167), 87.4% (n = 160), and 86.9% (n = 159) were correctly characterized according to their reference standard by each observer, respectively. In 13 cholangiocarcinomas, one to three were misinterpreted as HCC, and the remaining tumors were correctly characterized by each observer. The accuracies (Az) of MRI for HCC diagnosis were 0.952 for observer 1, 0.906 for observer 2, and 0.910 for observer 3, with 0.922 for pooled data. There was good inter-observer agreement.

Conclusion

The gadoxetic acid-enhanced MRI including DWI showed a reasonable performance for tumor characterization with high sensitivity for tumor detection in patients with chronic liver disease, despite concerns of high false positive diagnosis of hypervascular tumors.     

Lesions involving the fourth ventricle evaluated by CT and MR: A comparative study

A retrospective review of 21 patients with lesions involving the fourth ventricle was performed to determine the relative capability of computed tomography (CT) and MR for detection, characterization, localization, and diagnosis. Lesions involving the fourth ventricle included ependymoma (three), subependymoma (one), glioma (five), cysticercosis cyst (three), medulloblastoma (three), bleeding into the fourth ventricle (two), epidermoid cyst (two), “trapped” fourth ventricle (one), and lymphomatoid granuloma (one). Posterior fossa lesions that displaced but did not invade the fourth ventricle were excluded. Lesion detectability on CT was judged excellent in ten, good in 8, and fair or poor in 3. Detectability of lesions by MR was judged excellent in 16 and good in 5. There was complete agreement on lesion extension between CT and MR in 6 lesions, mild disagreement in 4, and moderate to significant disagreement in 11. Preoperatively, MR alone correctly diagnosed seven lesions, and CT alone correctly diagnosed three lesions. A review of the combined scans (after the correct diagnosis was given) showed both CT and MR were equal in the diagnosis of 14 lesions, MR better than CT in six, and CT better in one. There was complete agreement on both CT and MR with the surgical/pathologic findings in three lesions. Both studies proved disappointing in their ability to make the correct histologic diagnosis, probably because CT and MR characteristics may not always offer a definitive diagnosis and because of the wide spectrum of pathologic processes that may involve the fourth ventricle.     

Hypervascular hepatocellular carcinoma in the cirrhotic liver: diffusion-weighted imaging versus superparamagnetic iron oxide-enhanced MRI

Purpose

The purpose of the study was to validate diffusion-weighted imaging (DWI) in the assessment of hypervascular hepatocellular carcinoma (HCC) compared with superparamagnetic iron oxide (SPIO)-enhanced magnetic resonance imaging (MRI) in the cirrhotic liver.

Material and Methods

Forty-six consecutive patients with 106 hypervascular focal lesions in the cirrhotic liver who underwent DWI using three b factors and gadopentetate dimeglumine-enhanced dynamic MRI followed by SPIO-enhanced MRI were enrolled. Two independent radiologists evaluated two separated image sets (SPIO set, dynamic MRI and SPIO-enhanced T2*-weighted images; DWI set, DWI and dynamic MRI) and assigned confidence levels for diagnosis of HCC using a five-point scale for each lesion. Area under the receiver operating characteristic curve (A_z) was calculated for each image set.

Results

The A_z value of the DWI set was larger than the SPIO set by both readers (reader 1, 0.936 vs. 0.900, P=.050; reader 2, 0.938 vs. 0.905, P=.110). For the sensitivity (reader 1, 93.1% vs. 86.2%, P=.146; reader 2, 95.4% vs. 88.5%, P=.070) and specificity (reader 1, 89.5% vs. 73.7%, P=.250; reader 2, 79.0% vs. 73.7%, P=1.000) of HCC diagnosis, DWI sets were superior to SPIO sets without statistically significant differences.

Conclusion

For assessment of hypervascular HCC, DWI in combination with dynamic MRI provides comparable or slightly better information compared with the combination of dynamic and SPIO-enhanced MRI.     

Magnetic resonance imaging of simple and infected hydatid cysts of the brain

Hydatid cyst of the brain is more common in children than adults. The cyst is always solitary unless the primary site is the brain. Cerebral hydatid cyst (CHCy) is most frequently supratentorial involving the territory of the middle cerebral artery, especially the parietal lobe. This study included 16 patients who were treated for CHCy. They were 11 male patients (68.75%), and 5 female patients (31.25%), ranging in age from 6 to 40 years with an average age of 14.7 years. Most of the patients were children-12 patients (75%), between 6 to 16 years of age. All patients were from rural areas. Headache, vomiting and seizures were the predominant symptoms. Papilloedema was present in 12 patients (75%). CT and MRI were performed in all patients. The cysts were all located in the cerebral hemispheres, except one in the posterior fossa, (Rt. cerebellar hemisphere). One lobe alone was affected in 7 patients (43.8%), two lobes in 6 patients (37.5%) and 3 lobes in two patients (12.5%). Round, or oval well defined cystic lesions isointense to the CSF in T1 and T2WI, with hypointense walls in T2WI and no surrounding perifocal edema or evidence of contrast enhancement were seen in 12 patients (75%) and were classified as simple or non-complicated CHCy. Cystic lesions with surrounding, T2 hyperintense area of perifocal edema, complete and incomplete (segment) rim of contrast enhancement were seen in 4 patients (25%), and were labeled as complicated or infected cysts (cysts with superadded pyogenic infection). All patients were treated surgically, hydatid birth (delivery of unruptured cyst) was achieved in 10 patients, cyst rupture occurred in 6 patients (37.5%), with subsequent recurrence (3 patients with recurrent multiple cysts and 3 patients with recurrent solitary cysts). All the recurrent cysts were surrounded by perifocal edema and showed ring enhancement. MRI has proved to be an excellent means of studying CHCy. It will be more widely used for diagnosis and surgical planning. It provided information about the exact cyst localization, cyst contents and presence or absence of superadded cyst infection.     

采用DNA和蛋白质吸收带的Kubelka-Munk光谱函数检测人胃癌

采用DNA和蛋白质吸收带的Kubelka-Munk光谱函数对离体的人正常胃、未分化胃腺癌、胃鳞状细胞癌和低分化胃腺癌的上皮组织进行鉴别诊断。实验采用带积分球附件的分光光度计获取组织的漫反射光谱。结果表明：在250～650 nm,人胃的上皮组织的癌变导致未分化胃腺癌、胃鳞状细胞癌和低分化胃腺癌等的上皮组织的Kubelka-Munk光谱函数f(r∞)及其对数log[f(r_∞)]的平均值在DNA吸收带(260 nm)处都有非常显著性的差异,其差异分别为68.5%(p＜0.05),146.5%(p＜0.05),282.4%(p＜0.05)和32.4%(p＜0.05),56.0%(p＜0.05),83.0%(p＜0.05)。人胃的上皮组织的癌变导致未分化胃腺癌、胃鳞状细胞癌和低分化胃腺癌等的上皮组织的Kubelka-Munk光谱函数f(r_∞)及其对数log[f(r_∞)]的平均值在蛋白质的吸收带(280 nm)处也都有非常显著性的差异,其差异分别为86.8%(p＜0.05),262.9%(p＜0.05),660.1%(p＜0.05)和34%(p＜0.05),72.2%(p＜0.05),113.5%(p＜0.05)。人胃的上皮组织的癌变导致未分化胃腺癌、胃鳞状细胞癌和低分化胃腺癌等的上皮组织的Kubelka-Munk光谱函数f(r_∞)及其对数log[f(r_∞)]的平均值在β-胡萝卜素吸收峰(480 nm)处也有着显著的差异性,其差异分别为59.5%(p＜0.05),73%(p＜0.05),258.9%(p＜0.05)和118.7%(p＜0.05),139.2%(p＜0.05),324.6%(p＜0.05)。可见,人胃上皮组织的癌变导致其DNA、蛋白质和β-胡萝卜的含量都发生了显著的变化。这结论为快速、低成本、非入侵的胃癌的光活检及鉴别诊断胃癌提供有益参考。     

N-Acetyl peak in MR spectra of intracranial metastatic mucinous adenocarcinomas

Absence of N-acetylaspartate (NAA) is one important diagnostic criterion of MR spectroscopy (MRS) that may suggest that an intracranial mass lesion is a metastasis. We report two cases of histopathology-confirmed intracranial metastatic mucinous adenocarcinoma, which predominantly showed a large metabolite peak at 2.0 ppm, mimicking an NAA peak of normal brain tissue. This finding could be of help in the interpretation of MRS in cases of intracranial enhancing mass lesions, metastases or gliomas.     

MR imaging of radiation osteitis in the sacroiliac joints

The purpose of this study was to analyze magnetic resonance (MR) images of radiation osteitis of sacroiliac joints, retrospectively. Seven patients with radiation osteitis, which was diagnosed by pelvic plain radiographs and CT images, underwent MRI. T(1)-weighted spin echo images and T(2)-weighted fast spin echo images were obtained in all patients. Four patients were examined after gadolinium injection. Major signal changes of radiation osteitis were distributed on the iliac side. T(1)-weighted images showed diffuse low intensity both in sacral and iliac sides. T(2)-weighted images showed very low intensity adjacent to sacroiliac joints, but mixed intensity was illustrated apart from joints, and high intensity in the peripheral areas. Radiation osteitis showed slight to mild, but irregular enhancement in four patients after gadolinium administration. MRI can illustrate abnormal bone change distribution and is useful for diagnosing this entity by characteristic intensity patterns on T(1)-weighted images with and without gadolinium and T(2)-weighted image. However, the diagnosis of accompanied insufficiency fractures in the area of radiation osteitis is occasionally difficult with conventional MRI.     

Distinct patterns of active and non-active plaques using texture analysis on brain NMR images in multiple sclerosis patients: preliminary results

The benefits of texture analysis of magnetic resonance images have been assessed in multiple sclerosis (MS) patients. Out of thirty-two lesions identified in eight MS patients, nine were considered active, judging from their gadolinium uptake. Texture analysis allowed to obtain forty-two characterizing parameters for each lesion. Using discriminant analysis as a statistical method allowed to classify the lesions into two groups: active or non-active. An attempt to classify their level of activity by using only co-occurrence matrices was unsuccessful. Alternately, the same type of analysis performed on runlength analysis criteria allowed the accurate classification of 88% of active lesions and 96% of non-active lesions. Using incremental discriminate analysis can reduce the number of useful parameters. This method showed that among the 42 parameters, 8 only were highly significant and permitted an accurate classification. Five of these parameters are runlength parameters, and three others are more directly related to the global distribution. The main interest of runlength parameters is that they allowed to demonstrate that the lesion structure was different in active and non-active plaques. This preliminary work suggests that using texture analysis could be of interest in the follow-up of MS patients because it provides an opportunity to identify active lesions without frequent gadolinium injections.