Dwi mri abscess vs tumors . – irm-resonance magnetique-mri anoxia vs hypoxia

1: clin imaging. 2002 jul-aug;26(4):227-36. Links diffusion-weighted MRI features of brain abscess and cystic or necrotic brain tumors: comparison with conventional MRI.

• chang SC ,

• lai PH ,

• chen WL ,

• weng HH ,

• ho JT ,

• wang JS ,

• chang CY ,

• pan HB ,

• yang CF .

Department of radiology, veterans general hospital-kaohsiung, national yang-ming university, national sun yat-sen university, 386 ta-chung first road, kaohsiung, taiwan, ROC.

BACKGROUND AND PURPOSE:

The purpose of this study was to determine whether diffusion-weighted imaging (DWI) and apparent diffusion coefficient (ADC) can be used to distinguish brain abscesses from cystic or necrotic brain tumors, which are difficult to distinguish by conventional magnetic resonance imaging (MRI) techniques.Anoxia vs hypoxia


METHODS: eleven consecutive patients with brain abscesses [10 pyogenic and 1 toxoplasmosis (in an AIDS patient)] and 15 with cystic or necrotic brain gliomas or metastases were enrolled in this study. None of these lesions had apparent hemorrhage based on T1-weighted image (T1WI).

The DWI was performed using a 1.5-T system, single-shot spin-echo echo-planar pulse sequence with b=1000 s/mm(2). The ADC was calculated using a two-point linear regression method at b=0 and b=1000 s/mm(2).

The ratio (ADCR) of the lesion ADC to control region ADC was also measured.

RESULTS:

Increased signal was seen in all of the pyogenic abscess cavities to variable degrees on DWI.

In vivo ADC maps showed restricted diffusion in the abscess cavity in all pyogenic abscesses [0.65+/-0.16 x 10(-3) (mean+/-S.D.) mm(2)/s, mean ADCR=0.63].Anoxia vs hypoxia

The case with multiple toxoplasmosis abscesses showed low signal intensity on DWI and high ADC values (mean 1.9 x 10(-3) mm(2)/s, ADCR=2.24).

All cystic or necrotic tumors but one showed low signal intensity on DWI and their cystic or necrotic areas had high ADC values (2.70+/-0.31 x 10(-3) mm(2)/s, mean ADCR=3.42).

One fibrillary low-grade astrocytoma had a high DWI signal intensity and a low ADC value in its central cystic area (0.44 x 10(-3) mm(2)/s, ADCR=0.49). Postcontrast t1wis yielded a sensitivity of 60%, a specificity of 27.27%, a positive predictive value (PPV) of 52.94%, and a negative predictive value (NPV) of 33.33% in the diagnosis of necrotic tumors. DWI yielded a sensitivity of 93.33%, a specificity of 90.91%, a PPV of 93.33%, and a NPV of 90.91%.Anoxia vs hypoxia

The area under receiver operating characteristic (ROC) curves for postcontrast T1WI was 0.44 and DWI was 0.92.

Analysis of these areas under the ROC curves indicates significant difference between postcontrast T1WI and DWI (P.001).

CONCLUSION: with some exceptions, DWI is useful in providing a greater degree of confidence in distinguishing brain abscesses from cystic or necrotic brain tumors than conventional MRI and seems to be a valuable diagnostic tool.

PMID: 12140151 [pubmed – indexed for MEDLINE] related links

• diffusion-weighted MRI in cystic or necrotic intracranial lesions. [neuroradiology. 2000] PMID: 11110071

• brain abscess and cystic brain tumor: discrimination with dynamic susceptibility contrast perfusion-weighted MRI. [J comput assist tomogr. 2005] PMID: 16163039

anoxia vs hypoxia

• diffusion-weighted echo-planar MRI of the brain with calculated adcs: a useful tool in the differential diagnosis of tumor necrosis from abscess? [J neuroimaging. 2003] PMID: 14569825

• [diffusion-weighted MRI in the differentiation of brain abscesses and necrotic tumors] [tani girisim radyol. 2004] PMID: 15236124

• 1: clin imaging. 2002 jul-aug;26(4):227-36. Links

1: neuroradiology. 2006 aug 31; [epub ahead of print] links diffusion-weighted MR imaging of viral encephalitis.

• kiroglu Y ,

• calli C ,

• yunten N ,

• kitis O ,

• kocaman A ,

• karabulut N ,

• isaev H ,

• yagci B .

Department of radiology, pamukkale university school of medicine, TR-20070, denizli, turkey, drkiroglu@yahoo.Com.

INTRODUCTION: the aim of this study was to evaluate the role of diffusion-weighted imaging (DWI) in the diagnosis of viral encephalitis and its relationship with the stage of the illness.Anoxia vs hypoxia METHODS: we performed conventional magnetic resonance imaging (MRI) including T1-W, T2-W and fluid attenuated inversion recovery (FLAIR) sequences and DWI in 18 patients with viral encephalitis diagnosed on the basis of laboratory, clinical and radiologic findings. Based on the qualitative and quantitative comparison of the conventional MRI and DWI, the patients were divided into three groups. Apparent diffusion coefficient (ADC) values of the involved and contralateral normal brain tissues were computed and compared for each group. The degree of correlation between the time (TI) from the onset of neurologic symptoms to the MR examination and ADC values was determined. RESULTS: in group I (n=11) DWI was superior to conventional MRI in detecting the encephalitic involved sites and in depicting the borders of the encephalitic lesions.Anoxia vs hypoxia in group II (n=4) DWI was similar to conventional MRI. In group III (n=3) conventional MRI was superior to DWI. Mean ADC values of affected versus contralateral normal brain tissues were 0.458+/-0.161×10(-3) versus 0.86+/-0.08×10(-3) in group I, 0.670+/-0.142×10(-3) versus 0.93+/-0.07×10(-3) in group II, and 1.413+/-0.211×10(-3) versus 1.05+/-0.06×10(-3) in group III. Patients in group I had significantly lower ADC values than those in group II, while patients in group III had the highest ADC values (P0.05). The ADC values were significantly lower in the affected sites than in the unaffected sites of patients in groups I and II, but were significantly higher in the affected sites than in the unaffected sites of patients in group III (P0.05).Anoxia vs hypoxia there was an excellent correlation between ADC values and duration of the disease (r=0.874, P=0.01). CONCLUSION: DWI is superior to other conventional diagnostic MR sequences in the detection of early viral encephalitic lesions and depiction of the lesion borders and, in combination with other sequences, DWI may contribute to the determination of the disease phase.

PMID: 16944118 [pubmed – as supplied by publisher] related links

• diffusion-weighted MR imaging in japanese encephalitis. [J comput assist tomogr. 2004] PMID: 15538147

• [application of diffusion-weighted and perfusion magnetic resonance imaging in definition of the ischemic penumbra in hyperacute cerebral infarction] [zhonghua yi xue za zhi. 2003] PMID: 12899795

anoxia vs hypoxia

• multishot diffusion-weighted imaging features in spinal cord infarction. [J spinal disord tech. 2005] PMID: 15905774

• diffusion-weighted magnetic resonance imaging in acute stroke. [stroke. 1998] PMID: 9731595

• evolution of apparent diffusion coefficient, diffusion-weighted, and T2-weighted signal intensity of acute stroke. [AJNR am J neuroradiol. 2001] PMID: 11290470

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