대 한 방 사 선 의 학 회 지 1992 ; 28 (6) : 823~830 Journal of Korean Rad iological Society, November, 1992 Comparison of Brain MRI and CT of Diffuse Axonal Injury (DIA)* Jong Deok, Kim, M.D., Dong Woo, Park, M.D., Tchoong Kie, Eun, M.D. Deþartmeη t 01 Diαgnostic Radiology, J.ηie Unversity College 01 Mediciηe - Abstract- A retrospective comparative study of MRI and CT in 24 patients with diffuse axonal injury (DIA) was undertaken ‘ Three-quaters of the lesions were non-hemorrhagic, and the sites of involvement were lobar white matter (96%), corpus call osum (70 %), and rostral brainstem (42%), in descending order. MRI was singnficantl y more sensitive than CT in detecting DAI lesions. The average number of DAI lesions was higher with in­ creasin g clinical stage of the injury MRI is more valu able than CT for staging the full magnitude of the injury and in predicting the neurologic prognosis of DAI le sions. Index Words: Brain, trauma, 10.439 Brain, computed tomography, 11. 1211 Brain, magnetic resonance, 11. 1214 Brain, axon prevalent in DAI. INTRODUCTION The purpose of this study is to compare the capability of MRI and CT to detect and to stage Diffuse axonal injury (DAI) is a widespread the DAI lesions. dam age to axons in the white matter of the brain as 'a consequence of closed head trauma. The ma­ jority of the patients sHstain their injury in a road MATERIALS AND METHODS traffic accident, usually have severe impairment of consciousness from at the time of injury than A retrospective comparative study of MRI do patients with many other primary lesions and and CT in 24 patients with the clinical diagnosis have a lower inciden ce of fracture of the skull, of DAI was under'taken to evaluate the usefulness intracranial hematoma, cerebral contusion, and of both imaging modalities during the one-year raised intracranial pressure than patients without period from J anuary 1991 through D ecember DAI. 1991 MRI has clear advantages over CT in evalua Non-enhanced CT scans were obtained in all ting closed head trauma. Although its sensitivity patients within the first 24 hours aft er trauma in detecting hemorrhagic lesions is similar to that by using either TCT-80A or TCT-300A scan­ of CT, it is much better than CT in detecting ner, Toshiba. A slice thickness of lOmm was used non-hemorrhagic lesions, which are more in all insta nces. MRI was performed with a O.5T * 이 논문은 19 9 1 년도 인제대학교 장학재단의 연구비보조로 이루어졌음. 이 논문은 19 92 년 4 월 28일 접수하여 199 2 년 8월 21 일에 채택되었음 Received April 28, Accepted August 21 , 1992 - 823- Journal of Korean Radiological Society 1992; 28 (6) : 823~830 Toshiba MRT -50A scanner. The interval from Table 1. Age & Sex Distribution the lnJury to MRI evaluation was 1-17 days (mean, 5.6 days). All patients were examined 짧성 M F Total with both T 1-and T2 -weighted pulse sequences. 3 。 10 J Scans were obtained with a contiguous multislice ?-3 qJ 11 - 20 1i technique with a slice thickness of 5-8mm and 21 - 30 cJ oo interslice gap of 2mm. The T2-weighted scans q ’ 4 31 - 40 J i ‘ were obtained with a spin-echo sequences with ? nJ 41 - 50 J ? q4 . a repetiton time (TR) of 2500-3000 msec and 51 - 60 • echo time (TE) of 80 msec. T l-weighted scans 61 1i were obtained with a TR of 450-500 msec and Total 16 8 24 TE of 15-20 msec. Two or more imaging planes were used in all patients The MR and CT scans were analyzed in­ in stage III and 7 each were in stage 1 and stage dependently, and all abnormalities visualized II. Lobar white matter was the most common were classified by Adams’s staging of DAI (1) site of involvement (23/24;96%) (Fig. 1) , and according to increasing severity of the trauma: the next common sites were corpus collosum Stage 1, DAI lesions confined to the white mat­ (17/24; 70 % ) (Fig. 2) and rostral brainstem ter of the frontal and temporallobes, Stage II, (10/24; 42 % ) (Fig. 3) , in descending order. The lesions in lobar white matter as well as the white matter of frontallobe was most common­ posterior half of the corpus callosum, and Stage ly involved , and those of temporal and parietal III, additionallesions in the dorsolateral aspect lobes were the next. Posterior portion of the cor­ of the midbrain and upper pons. After initial in­ pus callosum (body and splenium) was more dividual analysis, the CT and MR scans were commonly involved than anterior portion. compared. Equivocal abnormalities seen on only Cerebellar white matter, internal capsule, and one study or one imaging plane were omitted basal ganglia were also involved. Associated le­ from the calculation. W e used the following sions.were as follows:cerebral contusion (n = 3), criteria to classify a lesion as hemorrhagic on epidural hematoma (n = 2) , and intraventricular­ MRI. On T 1-weighted image (T 1WI) , the (n = 1) and su barachnoid hemorrhages (n = 1) shortening of the T 1 relaxation time by Skull fracture and maxilla with zygoma fractures methemoglobin within the hemorrhagic lesion were seen in one case each. Total number of the had to be of sufficient degree that the hemor­ lesions detected on MRI (T2WI) was 201 , 26 % rhagic fo cus was at least partially hyperintense (53/201) of which were detectable on CT. The relative to white matter. On T2-weighted image number of DAI lesions ranged from 2 to 28 in (T2WI), we required the evidence of centtal hy­ one patient. The shape of the lesions was ovoid, pointensity (relative to brain parenchyma) within elliptical, small patchy, or short linear. Of 531e­ the hemorrhagic lesion sions detected on CT, 45 lesions (85 % ) were hemorrhagic. The ratio ofhemorrhagic to non­ RESULTS hemorrhagic lesion on MR was 50: 151 , reveal­ ing 75 % of DAI lesions consisted of non­ The male-to-fem ale ratio was 2: 1 and the age hemorrhagic (Table 3,4). The average numbers ran ge was 6 to 68 years old. Twenty-one of 24 of DAI lesions were 8, which were higher with cases (87.5 % ) were below 50 years old (Table 1). increasing severity of trauma, i.e., 5, 7, and 11 An analysis of the stage and the site of DAI in stage 1, II, and III, respectively (Table 4). lesions are given in Table 2. T en of24 cases were Cases with comatous or semicomatous m en- - 824- Jong Deok Kim , et al : Comparison of 8rain MRI and CT of Diffuse Axonal Injury Table 2. Sites of DAI Les ions on MRI (T2WI) Stage 1 Stage II Stage III Total 씩과「냐현e (n = 7) (n = 7) (n = 10) (n = 24) Lobar WM (23 /24) Frontal 6 5 8 19 Temporal 7 5 13 Pa ri etal 4 3 3 10 Occipi tal 0 0 0 0 Corpus call osum (17/24) Genu 2 2 4 Body 3 9 12 Splenium 4 6 10 Rostral brainstem ( 10124) 10 10 Other Cbl. WM 4 4 Int. capsule 4 5 Basal gangli a 4 3 8 Note: DAI = diffu se axonal lnJury WM = white matter Cbl. = ce rebell ar Int. = internal Fig. 1. Stage 1 DAI. 22 year-old­ female with drowsy mentality. Axial T2WI (TR/TE = 3000/ 120) obtained on the day ofhead injury (a) reveals multiple, small, focal high singal intensity lesions in the lobar white matter of the frontal and temporallobes. Brain CT (not shown) was normal. Five and a half months later (b), the number of the lesions decreased in accor­ dance with improvement of im­ paired consciousness. a. Initial b. 5.5M Later tality from the time of the injury were in stage duced by closed head traurna with rotationally II or stage III (8 /2 4). Three of the 4 cases who accelerated shear-strain at the mornent of irnpact. died within 10 days after the injury were in stage Closed head trauma with a significant inertial 11 1. component may produce differential inertia at areas of differing d ensity of fixation with resul­ DISCUSSION tant shearing injury at these sites. Shear-stra in Diffuse axonal injury (DAI) is the most com­ will be greatest at the junction of the tissues of m on type of primary tra urnatic intracra nial le­ different rigidity (gray/white-matter interface, sion constituting a pproximately 48% of all brain/CSF interface, skull/brain interface, dura prima ry lesions of head injury (1-3). It is pro- m ater/b rain interface). The gray-white m atter - 825 Journal of Korean Radi 이 ogical Society 1992; 28 (6) : 823""'830 junction is a prime example of just such an in­ Rotatory acceleration of the head is much terface, where differing density and differential more likely to occur during road traffic accident fixation among axons, cell bodies, and blood and in this situation the acceleration of the head vessels result in differential inertia causing distor­ is relatively of long duration. Subdural tion of the brain with tearing of the axons and hematom a and intracranial hematoma occur vessels. In DAI, widespread tearing ofaxons in significantly less frequently with increasing ac­ the cerebrum leads to disconnection of the cor­ celeration pulse duration , which are related to tex from lower center and hence to the state of the much lower incidence of raised intracranial coma, so the clinical hallmark of DAI is loss of pressure in DAI. Therefore, m ajority of the pa­ consciousness and DAI is a frequent cause of the tients with DAI sustain injury in a road traffic persistent vegetable state following head injury accident, never experience a lucid interval, and Because of their inherently low rigidity, neurons have a longer duration of survival than the pa­ are extremely susceptible to shear-strain defor­ tients in whom DAI has not occurred.