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Objective To quantitatively evaluate the influence of fluid attenuated inversion prepared recovery (FLAIR) on apparent diffusion coefficient (ADC) and its clinical application value. Methods The data of DWI and FLAIR-DWI of 139 stroke were retrospectively reviewed. Paired t-test was used to analyze DWI (ADCCON ) and FLAIR-DWI (ADCFLAIR) values at varying time points from hyperacute to chronic stage. All of the lesions were further divided into cortex involved infarction and subcortical infarction. The ADCCON and ADCFLAIR values in the lesion sides and the contralateral sides were compared separately. Results The mean ADCCON values for lesions less than 6 hours, 7--12 hours, 13--24 hours, within 2 days, 3-4 days, 5-7 days and 8--14 days were not significantly different from those of the ADCFLAIR values(P >0.05) [ADCCON were (0.55±0.07), (0.50±0.09), (0.50±0. 13), (0.50 ± 0. 13), (0.62 ± 0. 14), ( 0. 60 ± 0. 12), (0. 72 ± 0. 20) × 10-3 mm2/s; ADCFLAIR were ( 0. 53 ± 0. 09 ), (0.49±0.06),(0.49±0.10),(0.48±0.08),(0.58±0. 14), (0.60±0.09),(0.73±0.15) × 10-3 mm2/s]. Lesions of 15 to 30 days [ (0. 95±0. 21 ) × 10-3 mm2/s and ( 1.02±0. 27) × 10-3 mm2/s for ADCFLAIR and ADCCON ] and the chronic stage ( >31 days) [ ADCFLAIR and ADCCON were (1.10 ± 0. 30) × 10-3 mm2/s and (1.36±0. 41 ) × 10-3 mm2/s respectively], had a significantly lower ADCFLAIR than those of the ADCCON (P <0. 01 ). For patients with a symptom duration of less than 14 days, the mean ADCFLAIR values of the cortex involved and subcortical lesions were all not significantly different from the mean ADCCON (P > 0. 05 ) [ ADCCON were ( 0. 55 ± 0. 16 ), ( 0. 61 ± 0. 14 ) × 10-3 mm2/s ; ADCFLAIR were (0.53±0. 14), (0.60±0. 13) × 10-3 mm2/s]. For patients with a symptom duration of longer than 14 days, the mean ADCFLAIR values of the cortex involved and subeortical lesions were all significantly lower than those of the mean ADCCON values [ ( 1.16±0. 36) × 10-3 mm2/s vs. ( 1.35±0. 48) × 10-3 mm2/s for cortex involved lesions and (0. 97±0. 19) × 10-3 mm2/s vs. ( 1.15±0. 33) × 10-3 mm2/s for subcortical lesions ] (P < 0. 01 ). The ADC values of the normal contralateral sides were significantly decreased after the fluid inversion prepared pulse was conducted [ ADCFLAIR, ( 0. 76 ± 0. 05 ) × 10-3 mm2/s and ADCCON, (0. 82 ± 0. 11 ) × 10-3 mm2/s ] ( p < 0. 01 ). Conclusions The FLAIR significantly decrease the absolute ADC values of the ischemic lesions 14 days later after the stroke onset, which may be helpful in determining individual lesion age. Meanwhile, the application of FLAIR can have a more accurate relative ADC value by reducing the free fluid partial volume effect of the normal contralateral side, and hence enhance the ability of detecting the subtle ischemic pathophysiological changes.
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BACKGROUND: At present, MRI is the key method to examine the hippocampal sclerosis of the patients with epilepsy. The main results are the abnormal signals of hippocampus, in addition, other symbols of MRI can also suggest the hippocampal sclerosis.OBJECTIVE: To study the significance and value of the loss of visualization of digitations of hippocampal head in diagnosis of hippocampal sclerosis through the analysis of MRI on patients with temporal lobe epilepsy.DESIGN: Non-randomized, blind procedure(data selection, result evaluation), blank controlled and clinical experiment.SETTING: Departments of radiology in two universities.PARTICIPANTS: Between September 1996 and December 2002, 18 patients with temporal lobe epilepsy were selected from the Department of Radiology,Xinhua Hospital Affiliated to Shanghai Second Medical University. Meanwhile,patients with headache were diagnosed with MRI. Eighteen healthy people,whose ages were matched, were as control group.METHODS: Among 18 patients, MRI of 16 patients and 18 people in the control group were performed with a GE 1.5T Horizon MR unit and another 2with a GE 1.5T Signa whole body MR unit. With the double blind procedure, whether the digitations of hippocampal head of 72 hippocampal heads of 36 people in both patient and control groups exist or not was recorded by two radiologists with knowledge of hippocampal dissection but without knowing the condition of clinical operation. The results were divided into 3 levels:loss, poorly visible and existing, and hippocampal atrophy and abnormal signals were also recorded.MAIN OUTCOME MEASURES: Image condition of digitations of head,size of hippocampal head and changes of signal.RESULTS: Of 18 patients with hippocampal sclerosis, the abnormal findings included smooth and the loss of visualization of digitations of hippocampal heads seen in 16 patients, poorly visible of digitations of hippocampal head in one patient, and existence of digitations of hippocampal head in one patient. Hippocampal atrophy and high signals on T2-weighted images and fluid-attenuated inversion recovery imaging were seen in all patients. The sensitivity of loss of digitations of hippocampal heads for diagnosis of hippocampal sclerosis was 88.9% (16/18), and the specificity was 100%.CONCLUSSION: The loss of visualization of digitations of hippocampal head is a sensitive indicator for the diagnosis of hippocampal sclerosis. Atrophic changes of hippocampus combining with the increase of T2-weighted signal can definitely diagnose the hippocampal sclerosis.
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<p><b>OBJECTIVE</b>To calculate the volume embolization ratio of densely packing experimental aneurysms by three dimensional digital subtraction angiography (3D-DSA).</p><p><b>METHODS</b>Six experimental crotch aneurysms were created microsurgically in the common carotid artery of white rabbits. Two weeks later, each aneurysm's volume was measured with 3D-DSA surface shaded display(SSD) and the correction of lacteprene balloon calibration method. In the same time, the aneurysms were densely packed with electric detachable coils. The volume of coils that were used in each aneurysm was calculated separately. The ratio of coils volume and aneurysm volume was the volume embolization ratio (VER).</p><p><b>RESULTS</b>The aneurysms volumes measured by 3D DSA SSD ranged from 0.037 to 0.087 ml. The VER ranged from 23.5% to 32.5% (average 27.4%).</p><p><b>CONCLUSION</b>The minimum VER of densely packing experimental crotch aneurysms with electronic detachable coils was 23.5%.</p>
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Animals , Rabbits , Angiography, Digital Subtraction , Embolization, Therapeutic , Methods , Intracranial Aneurysm , Diagnostic Imaging , TherapeuticsABSTRACT
Purpose:To investigate the values of three newer contrast enhanced MRI sequences including gadolinium-enhanced FLAIR MRI(CE FLAIR), dynamic contrast-enhanced MRI (DCE MRI) and perfusion- weighted MRI(PWI) by comparing their advantages and disadvantages respectively in the diagnosis of intracranial tumors. Methods:43 patients with intracranial tumors underwent DCE MRI, CE FLAIR and PWI respectively. The gadolinium-enhanced FLAIR, dynamic enhanced MR and perfusion-weighted MR images were evaluated independently by two radiologists for the number of examinations with one or more enhancing lesions, the number and location of enhancing lesions per examination, the detectability for different lesions in different locations, size and extent of the lesions. Results:Perfusion-weighted MR images showed poor quality and could not give a diagnosis in 5 of 43 cases because of heavy susceptibility artifacts. There were 47 lesions in the 38 cases. However, 41 lesions were found on CE FLAIR MR images and 42 on DCE MRI and 45 on PWI. 3 lesions(2 located in the subcortical area and 1 in paraventricle) were only revealed on the CE FLAIR images. 4 lesions in the basal ganglia area were only found on dynamic enhanced images. 7 lesions in the cerebral hemisphere were only found on perfusion-weighted images. So there were significant differences in revealing lesions of different locations with the three MR modalities(P
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Objective To obtain magnetic resonance imaging(MRI) symptoms that could be used in medical diagnosis and identification by analyzing the diverse MRI appearance of brain multiple sclerosis(MS).Methods MRI findings of 41 samples of clinically definite MS, including the numbers, distributions, sizes, and shapes of the lesions were analyzed. The symbolic characteristics and enhanced expression are also covered.Results Brain MS might happen singly and multiply, and more frequently with multiple happening. In a multiple case, 4—15 lesions were observed the most. Some samples showed with diffuse lesions which were unable to be counted accurately presenting as a “dirty-appearing white matter”. The distribution of the lesions was observed most frequently at the two sides of periventricle, and following by the subcortical, corpus callosum, and brainstem. Only two lesions were observed at cerebrum. The size of most lesions range from a few millimeters to 2 cm, accounting for about 75% of the total samples. Lesions with size above 2 cm were seen seldomly, with the biggest one of 6—7 cm. According to the shapes and symptoms, lesions might be categorized as an acute and chronic ones. The acute lesions had a shape of oval or circle, with a swelling appearance, low signal of T_1WI, and isointensity or a slightly higher signal on the circle. T_2WI showed a high signal, with different increase and showing “core+lunar” sign. This kind of lesions showed an enhancement with the circle enhancement as the most typical one, which had a complete circle or non-conplete arc shape enhancement, even the big lesions. The chronic lesion might also be divided into two categories. One was the quasi-symmetric lesion, with the distribution along two sides of periventricle and with the shape of small puncture/patch, part of them merged into the big patch; another kind of lesions was found scattered sparsely at frontal, parietal lobes and two sides of the periventricle, with small patches in shape. The chronic lesions had an appearance of shrinking, sharp edge, even signals, and had no lunar circle phenomena and obvious enhancement.Conclusion Brain MS have diverse MRI appearence, with some of which are unique and symbolic.
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Objective:To improve the CT and MRI diagnostic accuracy of intracranial atypical cavernous angiomas(ACA).Methods:We retrospectively analyzed CT and MRI appearances,operative and pathological findings of 12 cases with ACA.Of them,11 cases were seanned by CT,10 cases by MRI and 9 by both CT and MRI.Results:Of 12 cases:One case as located at the sella ,1 case was at the fourth ventricle,5 cases were located at the cerebral hemisphere,4 cases were located at the middle cranial fossa and 1 case was at the posterior cranial fossa.There was edema in 3 cases,1 case had cystic component and 4 cases had cerebral hemorrhage.The localized rate of ACA by CT and MRI was 100%,but 11 cases were misdiagnosis and 1 case did not made the qualitative diagnosis. Conclusion:The qualitative diagnosis of ACA have some difficulty,so that the emphasis should be on the analysis of the combination imagiology and clinic.
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Objective To determine the reliability of CT perfusion scans and its parameters of ?-variate curve in evaluating the acute myocardial infarction for clinical reference of diagnosis on coronary artery disease and myocardial infarction. Methods Imatron C-150 electron beam CT (EBCT) were used to scan a hydrodynamic model which could mimic a change of contrast medium by intravenous injection in vivo. Then 6 adult canines were employed in the experiment with thoracic operation, and branches of the anterior descending and circumflex of left coronary arteries (LCA) were ligated so that myocardial infarction was made out. After intravenous administration of contrast medium, the hearts were scanned with perfusion EBCT and ?-variate curves were manifested. Some heterogeneities and differentiations between the normality and the infarctions were put forward when the parameters of all these curves were analyzed and statistically processed. Two myocardial infarctions were also verified by SPECT, and all the samples stained with TTC method were compared with those on the perfusion images. The pathological study with optical microscope and electron microscope were further carried on. Results The ascending slopes of ?-variate curves were different in the perfusion quantity. The normal curve of canine myocardium showed a somewhat quick ascending pattern first, and then a gradual descending pattern successively, with the ascending time of about 10-13 s, ascending CT value of about 34-37 HU, and peak CT value of about 70-81 HU. Whereas the curve on myocardial infarction demonstrated a prolonged ascending time of about 19.9 s, diminished ascending CT value of only about 20 HU, and peak CT value of about 53.8 HU, which were significantly different from the normality (P
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Objective To evaluate the accuracy of MR diffusion weighted imaging (DWI) in the diagnosis of hyperacute cerebral infarction. Methods Twenty one patients with onset of strokelike symptoms underwent conventional MRI and DWI within 6 hours. Results DWI indicated cerebral infarction in 16 patients, all of whom had a final diagnosis of acute stroke. DWI was negative in 5 patients, all of whom had a final diagnosis of TIA. The abnormality seen at DWI was confirmed with follow up study. DWI had a sensitivity of 100% and a specificity of 100% in the diagnosis of hyperacute cerebral infarction, and conventional MRI interpretation yielded a sensitivity and specificity of 25% and 100%, respectively. Conclusion DWI is highly accurate in diagnosing hyperacute cerebral infarction and is superior to conventional MRI.
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Objective To explore the clinical promise of CT 3D reconstruction of tracheobronchial tree(TBT) by analyzing 73 cases retrospectively. Methods All the 73 cases were collected from October 1997 to February 2000, who were scanned by EBCT with 130 kV and 630 mA. The scanning method was continuous volume scan, the slice thickness were 3 mm or 1.5 mm. All cross-sectional images were transmitted to the INSIGHT workstation and reconstructed with SSD (shaded surface display), and the threshold setting were -500 to -300 HU. Results 3D reconstruction of TBT with EBCT could reveal the abnormal changes of TBT by many kinds of diseases including central cancer, inflammation, bronchiectasis, saber-sheath trachea, trachea cancer, congenital disorders, post-surgical changes of lung cancer, and stenoses by adjacent benign or malignant diseases. It could be used to locate the stenoses and measure stenostic extent. Of the 35 central cancer cases with 3D reconstruction, 6 cases were pestle obstructed, 15 cases cone obstructed, 5 cases interrupted irregularly, 8 cases with eccentric stenoses, and 1 case with right stem destroyed and right upper lobe bronchus obstructed. Conclusion 3D reconstruction of TBT has characteristic sign in the diagnosis or differential diagnosis of central airway′s benign or malignant stenoses, and it is of instructional value in clinical use.
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Objective To explore the significance and value of loss of digitations of hippocampal head in diagnosis of hippocampal sclerosis.Methods Eighteen patients with hippocampal sclerosis comfirmed by histopathological examination and 18 cases to be matched control group were examined by MRI . The digitations,atrophic change and abnormal signals of hippocampal head were evaluated retrospectively.Results Of 18 patients with hippocampal sclerosis, loss of digitations was seen in 16 cases, poorly visible in 1 case and exist in 1 case. The sclerotic hippocampal heads all had atrophic change and were hyperintensity on T_2-weighted and FLAIR MR imagings. No loss of digitations were seen in the opposite side of the hippocampal sclerosis and all hippocampal heads in control group.Conclusion The loss of digitations of hippocampal head is a sensitive indicator for the diagnosis of hippocampal sclerosis.
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Objective To assess the clinical history and MRI findings of pituitary adenoma of different hormonesecreting type.Methods We retrospectively studied 200 postoperated patients,from 1996 to 2000,who all had the preoperated MRI exams.All cases had histopathological evalutions.Both clinical presentation(age,sex,symtom,sign)and MRI findings(size,form,signal intensity,extension)were investigated.Results There was a great span of age with sixty percent owing for 35～55 years old.The male and female proportion was 1∶2 in PRL hormone-secreting pituitary adenoma.12 cases with luleinizing hormone-secreting and 2 cases with thyrotropin hormone-secreting pituitary adenoma were just male.In other types the incidences were similar in man and woman.Clinical symptom and sign present overlapping.The volume of tumor was from 0.5 cm?0.8 cm?1 cm to 6 cm?7 cm?8 cm with most multihormone adenoma's maxium dimension out of 5 cm.The signal intensity was not characteristic pre-and post-enhancement.No calcification could be seen.In term of extension,most was to suprasellar,then infrasellar,unilateral or bilateral sinus cavernous,last was to lower part of the third ventricle.Conclusion Different hormonesecreting pituitary adenomas have some speciality in clinical and MRI presentation.Although an accurate diagnosis can not be made according to it,more information have been obtained.
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Objective To evaluate the value of dynamic susceptibility-contrast (DSC) MR perfusion imaging in differentiating benign and malignant meningiomas on the basis of differences in their vascularity in both tumor parenchyma and peritumoral region. Methods 33 patients with pre-operation meningiomas(25 benign and 8 malignant) underwent conventional and DSC MR perfusion imaging. Maximum relative cerebral blood volume (rCBV) and corresponding relative mean transit time (rMTT) values of the same part in both tumor parenchyma and peritumoral region were calculated (compared with contralateral normal white matter). The peritumoral region was defined as the area immediately adjacent (0.05) in parenchyma part and both were statistically significant (t test, ?
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Objective To study the different patterns of hippocampal atrophy by MRI segmental analysis and to investigate the etiology and pathogenesis of temporal lobe epilepsy Methods GE 1 5 T Signa Horizon LX MRI scanner was used Oblique coronal T 1 weighted images perpendicular to the long axis of the hippocampus were obtained The mesial temporal structures were divided into four parts: the amygdala, hippocampal head, body and tail MRI patterns of atrophy in 50 patients with histologically confirmed hippocampal sclerosis were investigated by MRI volumetric measurement and segmental analysis, and the differences of clinical features and surgical outcome in different groups were compared Results Diffuse hippocampal atrophy was found in 22 of 50 patients (44%), 5 of the 50 patients (10%) showed diffuse atrophy involving both the amygdala and hippocampus 20 of the 50 patients (40%) had hippocampal focal atrophy and 8 of 50 patients (16%) had no obvious atrophy 38 of 50 (76%) hippocampal sclerosis had atrophy in the hippocampal body, 29 of 50 (58%) had hippocampal head atrophy, 24 of 50 (48%) had hippocampal tail atrophy, and the least involved part was the amygdala (16%, 8/50) 10 patients who had normal hippocampal volume showed focal hippocampal atrophy by segmental analysis Various patterns of hippocampal atrophy were found to be statistically related to the duration of epilepsy, the frequency of seizure and the outcome of surgery, respectively ( P 0 05) Conclusion MRI segmental analysis can improve the diagnostic sensitivity of temporal lobe epilepsy and help to investigate its etiology and pathogenesis
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0.05). Four lesions were only revealed on CE FLAIR whereas 7 lesions were only found on postcontrast T_1WI. Enhancing lesions located in cerebral hemisphere or the forth ventricle was revealed much more on T_1WI than that on CE FLAIR. However, postcontrast fast FLAIR images may be useful in detecting superficial abnormalities and those located in sulcus or lateral ventricle. The enhancement degree of enhanced T_1WI was much more intense than that of CE FLAIR(P0.05) and statistical significance in GWC, CNR and CER(P
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Objective To explore the MRI and pathologic characteristics of hippocampal sclerosis. Methods 16 patients with hippocampal sclerosis were examined with transvers and oblique coronal T 1 weighted,T 2 weighted and fluid attenuated inversion recovery(FLAIR) MR imaging. Results Of 16 patients,1 case had bilateral hippocampal sclerosis;15 cases were ipsilateral(left n =9,right n =6) proved by pathology.The MR features of hippocampal sclerosis were as follows:hippocampal atrophy present in all patients;hyperintensity on coronal FLAIR in all patients and on coronal T 2W images present on 15 sides; loss of superficial sulci hippcampal head seen in 11 sides;disruption of the internal structures present on 13 sides; atrophy of lateral white matter present on 7 sides; enlargement of the ipsilateral temporal horn present on 6 sides;atrophy of the ipsilateral temporal lobe seen on 2 sides. Conclusion Atrophy and hyperintensity on coronal FLAIR and T 2 weighted images were the most common features of hippocampal sclerosis and had positive diagnostic value. Combination of coronal FLAIR and T 2 weighted imaging could improve the diagnostic sensitivity and accuracy for hippocampal sclerosis.
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Objective To investigate the value of MR perfusion-weighted imaging(PWI)in the evaluation of therapeutic effect of brain metastases with gamma knife.Methods Treatment by gamma knife before and after that 3 months or 6 months PWI studies were penformed respectively in 22 patients with brain metastases .Maps of relative regional blood volume(rCBV)and mean transit time(MTT)were obtained.The ratios of rCBV and MTT of lesions were analyzed.Results rCBV of tumors in 22 cases was increased.The ratios of maximum rCBV of the lesions and opposite side were 6.16?3.12 and 1.18?0.17 respectively.The ratios of MTT of the tumors was 1.44?0.53.After gamma knife treatment,9 of 22 cases appeared decreased rCBV,but the ratios of MTT were no changing,of them,3 cases presented cerebral necrosis.13 of 22 cases,the ratios of rCBV were increased in varied degree after treatment by gamma knife,and 6 cases presented brain radionecrosis.Conclusion PWI is a significant method in evaluating the therapeutic effect of brain metastases with gamma knife