Download The importance of diffusion-weighted imaging (DWI) for delineating

RAJIV GANDHI UNIVERSITY OF HEALTH SCIENCES, KARNATAKA
BANGALORE
ANNEXURE – II
PROFORMA FOR REGISTRATION OF SUBJECTS FOR DISSERTATION
1.
Name of the Candidate &
Address (In block letters)
:
Permanent Address
:
DR. GOVINDA RAJU .B.T
DEPT OF RADIODIAGNOSIS
MAHADEVAPPA RAMPURE
MEDICAL COLLEGE, GULBARGA
585105.
DR. GOVINDA RAJU.B T
#12, MANJUNATHA NILAYA ,2 ND B
CROSS , SIR MV NAGAR
RAMAMURTHYNAGAR
BANGALORE 560016
2.
Name of the institution
:
H.K.E. SOCIETY’S
MAHADEVAPPA RAMPURE
MEDICAL COLLEGE-585105
3.
Course of study and Subject
:
M.D. RADIODIAGNOSIS
4.
Date of admission to Course
:
30th May 2013
5.
Title of the topic
:
ROLE OF DIFFUSION WEIGHTED
MR IMAGING AND APPARENT
DIFFUSION COEFFICIENT FOR
THE EVALUATION OF
INTRACRANIAL LESIONS AT
BTGH, GULBARGA.
6.
Brief resume of the intended work
6.1 Need for the study:
MR Imaging has become an indispensable tool in the evaluation of intracranial
lesions. Diffusion Weighted MR imaging is now a routine component of the brain
MR imaging examination and is critical in the evaluation of stroke patients.
Diffusion-weighted magnetic resonance (DW MR) imaging provides image contrast
that is different from that provided by conventional MR techniques. It is particularly
sensitive for detection of acute ischemic stroke and differentiation of acute stroke
from other processes that manifest with sudden neurologic deficits. Diffusionweighted MR imaging also provides adjunctive information for other cerebral
diseases including neoplasms, intracranial infections, traumatic brain injury, and
demyelinating processes.1 High signal intensity on diffusion MR and hypointensity on
apparent diffusion co-efficient (ADC) images, which are features of acute cerebral
infarction, have been reported in such diverse conditions as hemorrhage, abscess,
tumor and even in Wernickes encephalopathy. Differentiating between these
conditions is critical for determination of appropriate treatment. 2 Because stroke is
common and in the differential diagnosis of most acute neurologic events, diffusionweighted MR imaging should be considered as an essential sequence, and its use in
most brain MR studies is recommended.1
Diffusion-weighted magnetic resonance (DW MR) imaging provides potentially
unique information on the viability of brain tissue. It provides image contrast that is
dependent on the molecular motion of water, which may be substantially altered by
disease. The method was introduced into clinical practice in the middle 1990s, but
because of its demanding MR engineering requirements—primarily high-performance
magnetic field gradients—it has only recently undergone widespread dissemination.
The primary application of DW MR imaging has been in brain imaging, mainly
because of its exquisite sensitivity to ischemic stroke—a common condition that
appears in the differential diagnosis in virtually all patients who present with a
neurologic complaint. 1
The technique most commonly used to acquire the DWI is an ultrafast one, echoplanar imaging (EPI); this technique decreases scanning time significantly and
eliminates movement artifacts and imaging time ranges from a few seconds to two
minutes.1
6. 2
REVIEW OF LITERATURE
Diffusion-weighted magnetic resonance (MR) imaging provides image contrast
that is different from that provided by conventional MR techniques. It is particularly
sensitive for detection of acute ischemic stroke and differentiation of acute stroke
from other processes that manifest with sudden neurologic deficits.1 Diffusionweighted MR imaging also provides adjunctive information for other cerebral
diseases including neoplasms, intracranial infections, traumatic brain injury, and
demyelinating processes. Because stroke is common and in the differential diagnosis
of most acute neurologic events, diffusion- weighted MR imaging should be
considered an essential sequence, and its use in most brain MR studies is
recommended1.
Diffusion MR imaging is now a routine component of the brain MR imaging
examination and is critical in the evaluation of stroke patients. The signal intensity of
acute stroke on DW images increase during the first week after symptom onset and
decrease thereafter, but signal remains hyper intense for a long period .2
Epidermoid tumors demonstrate ADCs similar to those of gray matter and lower than
those of CSF and appear markedly hyperintense compared with CSF and brain tissue
on DW images.2
Most benign meningiomas are isointense on DW images and ADC maps. High signal
intensity on DW images and reduced ADC values (0.4-0.69 x10¯³mm²/sec) suggest
malignant meningiomas. DW MR imaging provides unique information about the
physiologic state of brain tissue. It has tremendous potential for helping direct the
treatment of acute ischemic stroke2.
The purposes of this study were to find the role of diffusion-weighted MR imaging in
characterizing intracerebral masses and to find a correlation, if any, between the
different parameters of diffusion-weighted imaging and histologic analysis of tumors.
The usefulness of diffusion-weighted imaging and apparent diffusion coefficient
(ADC) maps in tumor delineation was evaluated.3
For tumors, the diffusion-weighted images and ADC maps of gliomas were less
useful than the T2-weighted spin-echo and contrast-enhanced T1-weighted spin-echo
images in definition of tumor boundaries.3
The high sensitivity and specificity of echo-planar diffusion-weighted imaging in the
diagnosis of acute cerebral infarction is widely accepted . The reduced diffusion
typical of acute stroke is thought to be related to the cytotoxic edema and shrinking of
the extracellular space. We can hypothesize that diffusion-weighted imaging may
enable us to differentiate various tumor components and to distinguish tumoral
invasion from normal tissue or edema3.
Diffusion magnetic resonance imaging (MR) utilizes the Brownian motion of
molecules to derive images. In acute stroke, DWI demonstrates decreased
diffusion in a vascular territory affected by ischemia. Similarly, decreased
diffusion is present in the center of pyogenic abscesses and aids in the MR
diagnosis of a ring-enhancing cerebral mass.4 In addition, tumors such as
lymphoma and PNET also demonstrate decreasing diffusion, adding valuable
information to the radiologist when formulating a differential diagnosis of a
cerebral mass lesion. There are also growing applications in differentiating tumors
such as glioblastoma primary cerebral lymphoma, and metastasis4.
The importance of diffusion-weighted imaging (DWI) for delineating acute ischemic
lesions has been investigated extensively; however, few studies have investigated the
role of DWI in the subacute stage of stroke.5 Interleaved echo-planar DWI with phase
navigation was performed on a 1.5-T MR unit in a consecutive series of 53 patients
(mean age, 66 6 14 years) with suspected recent cerebral ischemia.
DWI clearly delineated recent ischemic damage in 39 patients (74%) as compared
with 33 (62%) in whom lesions were identified or suspected on conventional T2weighted im- ages. DWI provided information not accessible with T2-weighted
imaging in 17 patients when evidence of lesion multiplicity or detection of clinically
unrelated recent lesions was included for comparison5.
Recent ischemic damage is better shown on DWI sequences than on conventional
and contrast-enhanced MR images throughout the first days after stroke and may
provide further information about the origin of clinical symptoms5.
Pyogenic abscess-- Increased viscosity in a pyogenic abscess or empyema due to
inflammatory debris, cellularity, and protein content results in homogeneous
restriction of ADC and hyperintensity on DW. This property aids in the
differentiation of an intracranial abscess and a centrally necrotic neoplasm, both of
which can appear as similar ring-enhancing lesions on conventional imaging.6 On
DWI, a subdural empyema will typically show hyperintense signal with reduced
ADC, similar to pyogenic parenchymal abscesses. Conversely, sterile effusions have
elevated ADC similar to cerebrospinal fluid (CSF) and are thus typically hypointense
on DWI6.
Herpes encephalitis is characterized by cytotoxic edema, frequently involving the
temporal lobes, resulting in marked hyperintensity on DWI and restricted ADC. As
herpes encephalitis may occasionally mimic infiltrative tumors of the temporal lobe
on conventional imaging, diffusion imaging can help differentiate herpes from tumor,
as the ADC of such tumors is typically elevated, contrasting with the reduced ADC
of herpes encephalitis6.
Subclinical acute ischaemic lesions on brain magnetic resonance imaging have
recently been described in spontaneous intracerebral haemorrhage, and may be
important to understand pathophysiology and guide treatment7.Acute, subclinical
ischaemic brain lesions are frequent but previously underestimated after intracerebral
haemorrhage, and are three times more common in cerebral amyloid angiopathyrelated intracerebral haemorrhage than in other intracerebral haemorrhage
types.7Diffusion-weighted imaging lesions contribute to the overall burden of
vascular-related brain damage in intracerebral haemorrhage, and may be a useful
surrogate marker of ongoing ischaemic injury from small-vessel damage7.
The most frequent intracranial appearance in children with neurofibromatosis type
1 (NF1) is represented by the presence of hyperintense lesions on T2-weighted
images, the so-called “unidentified bright objects” (UBOs). Di Paolo demonstrated
that these lesions represent foci of myelin vacuolization with increased water content
Compared with the controls, NF1 patients showed higher ADC values (P < 0.001) in
all locations. In the NF1 group, the mean ADC value in the UBOs was higher than in
other locations (P < 0.001)8.
The higher ADC values in children with NF1 suggest an increase in water content of
the normal-appearing brain. The UBOs are the areas with the highest water content.
The regressed UBOs sites show higher water content than the normal-appearing area8
To determine whether diffusion-weighted imaging by using minimum apparent
diffusion coefficient (ADCmin) values could differentiate various brain tumors
including gliomas, metastases, and lymphomas. On diffusion-weighted imaging, the
ADCmin values were measured within the tumors and mean values were evaluated
regarding statistical differences between groups.9
The ADCmin values of low-grade gliomas(1.09 ± 0.20 × 10−3 mm2/s) were
significantly higher (p < .001) than those of other tumors. The ADC measurements
may help to differentiate low-grade gliomas from high-grade gliomas, metastases, and
lymphomas9.
High sensitivity (94%) and specificity (100%) have been reported in the diagnosis of
acute cerebral infarction with diffusion-weighted magnetic resonance (MR) imaging.
However, high signal intensity on diffusion-weighted MR images and low apparent
diffusion coefficient values (similar to the findings in acute cerebral infarction) were
reported in such diverse conditions as hemorrhage, abscess, lymphoma and even
Creutzfeldt-Jakob disease. The differential diagnosis of these conditions (eg, acute
ischemic infarction and acute cerebral hemorrhage) is critical for the determination of
appropriate treatment.10
6.3 OBJECTIVES OF STUDY:
 To study the appearance of various lesions of brain on DWI & ADC maps.
 To evaluate the usefulness of DWI, ADC maps over conventional MRI in
differential diagnosis of various lesions.
 To diagnose conditions which are not apparent on conventional MRI.
7
MATERIAL AND METHODS:
7.1 SOURCE OF DATA:
The patients who were referred to radiology department basaveshwara teaching and
general hospital for MRI brain. This consists of a study of 100 patients from nov
2013 to march 2015.
7.2 METHODS OF COLLECTION OF DATA
(Including sampling procedures) In all patients detected to have intracranial lesions
on MRI of the brain, at the Department of Radiodiagnosis basaveshwara hospital the
DWI findings will be noted and correlated with ADC and T2 FLAIR images.
Based on their signal intensity these lesions will be grouped into one of the following.
1. DWI hypointense, ADC hyperintense, T2 FLAIR hyperintense
2. DWI hypointense, ADC hyperintense, T2 FLAIR isointense
3. DWI isointense, ADC hyperintense, T2 FLAIR hyperintense
4. DWI hyperintense, ADC hypointense, T2 FLAIR isointense
5. DWI hyperintense, ADC iso-hyperintense,T2 FLAIR hyperintense
6. DWI hyperintense, ADC hypointense, T2 FLAIR hyperintense
For evaluation of the brain, MRI will be performed using a 1.5 tesla MRI
scanner .(Philips achieva) Sagittal T1, axial T2 FLAIR and diffusion weighted images
with ADC maps will be taken.
STATISTICAL METHODS
Data will be analysed using appropriate statistical test like proportions , percentages ,chi
square test etc using SPSS software.
Inclusion criteria:
- All patients who are detected to have any of the following intracranial lesions on
MRI brain:
stroke
Infective conditions
Metabolic or toxic insults to the brain
Demyelinating disorders
Degenerative disorders
Tumors
Exclusion criteria:
Patients who are detected to have intracranial bleed
7.3 DOES THE STUDY REQUIRE ANY INVESTIGATION OR
INTERVENTION TO BE CONDUCTED ON PATIENTS OR OTHER
HUMANS OR ANIMALS? IF SO PLEASE DESCRIBE BRIEFLY. YES.
The study requires the use of diffusion weighted magnetic resonance imaging on the
patients as part of evaluation of the suspected intracranial lesion.
7.4
HAS EHTICAL CLEARANCE BEEN OBTAINED FROM YOUR
INSTITUTION IN CASE OF 7.3?
YES. Ethical clearance has been obtained from ethical clearance committee of the
institution.
8.
LIST OF REFERENCES:
1 Diffusion-weighted MR Imaging of the Brain Pamela W. Schaefer, MD, P. Ellen
Grant, MD, and R. Gilberto Gonzalez, MD, PhDFrom the Neuroradiology Division,
Massachusetts General Hospital, GRB 285, Fruit St, Boston, MA 02114-2696.
Received April 30, 1999;
2Clinical applications of diffusion weighted MR imaging: A review
Rajeshkannan, Moorthy, KPSreekumar, RRupa, NKPrabhuDepartment Radiology,
Amrita Institute of Medical Sciences, Amrita Lane, Elamakkara (PO), Ernakulam.
Kerala, India2006
3 Diffusion-weighted MR Imaging of Intracerebral Masses: Comparison with
Conventional MR Imaging and Histologic Findings
Tadeusz W. Stadnika, Cristo Chaskisa, Alex Michottea, Wael M.
Shabanaa,AJNR 2001 22: 969-976
4 Diffusion MR Imaging of the Brain in Patients with CancerJ. Matthew
Debnam and Dawid SchellingerhoutDepartment of Radiology, Section of
Neuroradiology, The University of Texas MD Anderson Cancer Center, 1400 Pressler
Street, FCT16.024, Unit 1482, Houston, TX 77030, USA Received 1 June 2011
5 Diffusion-weighted Imaging of Patients with Subacute Cerebral Ischemia:
Comparison with Conventional and Contrast-enhanced MR Imaging
Michael Augustin, Roland Bammer, Josef Simbrunner, Rudolf Stollberger,
Published in 2000.
6 Diffusion MRI: Overview and clinical applications in neuroradiology
Luis C. Maas, MD, PhD and Pratik Mukherjee, MD, PhD.2005
7 Acute ischaemic brain lesions in intracerebral haemorrhage: multicentre crosssectional magnetic resonance imaging study
Simone M. Gregoire1, Andreas Charidimou1, naveen
Gadapa1, Brain (2011) 134 (8): 2376-2386.doi: 10.1093/brain/awr172
8 Brain Apparent Diffusion Coefficient Evaluation in Pediatric Patients With
Neurofibromatosis Type 1Tognini, Giuseppe MD*; Ferrozzi, Francesco MD*;
Garlaschi, Giacomo MD† May/June 2005 - Volume 29 - Issue 3 - pp 298-304
9 Minimum apparent diffusion coefficients in the evaluation of brain tumorsOmer
Kitisa, Hakan Altaya, Cem Callia, Nilgun Yuntena September 2005, Pages 393–400
10 Differential Diagnosis of Bright Lesions on Diffusion-weighted MR
ImagesTadeusz W. Stadnik, MD, PhD, ,, Robert R Luypaert, PhD, © RSNA, 2002
9.
Signature of Candidate
10.
Remarks of the Guide
11.
NAME & DESIGNATION
(in block letters)
12.
11.1
Guide
11.2
Signature
11.3
Co-Guide
11.4
Signature
11.5
Head of the
Department
11.6
Signature:
12.1
Remarks of the
Chairman & Principal
12.2
Signature
The study has immense value in the
management of patients with intracranial
lesions and has been suggested by me as a
topic for dissertation.
DR. SURESH.B . MASIMADE
MD R.D
PROFESSOR & H.O.D.,
DEPT OF RADIOLOGY,
M.R. MEDICAL COLLEGE,
GULBARGA.
DR. SURESH B. MASIMADE
MD R.D
PROFESSOR & H.O.D.,
DEPT OF RADIOLOGY,
M.R. MEDICAL COLLEGE,
GULBARGA.