MAGNETIC RESONANCE IMAGING - VALUABLE &
SENSITIVE TECHNIQUE IN RELATION TO
CONVENTIONAL RADIOGRAPHS OF HIP PAIN
Dr. Parveen Chandna
PG Student M.D. Radio-Diagnosis
Department of Radio Diagnosis, JJM Medical College,Davangere, Karnataka
ABSTRACT
Hip pain has different etiologies in adults and children Imaging
modalities used to evaluate hip pain and the appropriateness of particular
studies in different clinical senarios have been practically demonstrated at
Bapuji Hospital and Chigateri General Hospital attached to JJM Medical
College, Davangere (Karnataka) during the year 2014. The history of the
patients and selection of imaging tests examination played a key role to develop
a differential diagnosis. Plain film could not detect early pathologies like AVN,
articular cartilage pathology and soft tissue involvement. Whereas, MR imaging
has been found to be the most sensitive modality for imaging AVN and found to
be uniquely capable of depicting the soft tissue abnormalities in cases of
arthrititisand TB of hip including synovial inflammation and articular cartilage.
Keywords : Antero-posterior view (AP view), Avascular necrosis (AVN),
Developmental dysplasia of hip (DDH), Fast spin echo (FSE), Gradient echo
(GRE), Juvenile rheumatoid arthritis (JRA), Legg-Calve-Perthes (LCP),
Multiecho fast field echo (mFFE) Magnetic resonance imaging (MRI),
Osteoarthritis (OA), Proton Density (PD), Short tau inversion recovery (STIR),
Tuberculosis of hip (TB HIP)
1
INTRODUCTION
MRI is regarded as gold standard in evaluation of soft tissue and articular
cartilage which have several limitations for pathological detection based on
plain radiography. Imaging of the hip has been regarded as the most valuable
tool in the evaluation of disorders related to hip because articular structures,
extra-articular soft tissue and the osseous structures associated with hip disease
can be well established1. The principal advantage of the true coronal and axial
planes commences with symmetric, bilateral images both of which provide an
important clue in diagnosis and time factor. The femoral head, neck and the
intertrochantric region can be very well demonstrated on coronal MR images.
Axial MR images provide good visualisation of the articular space, hip
musculature and supporting ligaments2. MR imaging is performed to detect
avascular necrosis (AVN) in its earlier stages to facilitate early treatment and
prevention of subsequent bone destruction. Thus, screening of asymptomatic
and high risk patients can be carried out at the budding stage due to the most
sensitive modality for imaging AVN.
Moreover, imaging has become most meaningful in the diagnosis and
management of pediatric hip disorders as juvenile normal hip is solely
dependent on proper seating of the femoral head in the acetabulum.
Visualisation of Juvenile rheumatoid arthrititis and Sarcoidosis patients with
musculoskeletal complaints and intra articular pathology associated with
alterations in bone marrow is a unique features of MR imaging. Therefore,
conventional radiographs and MRI are the best provisions in comprehensive
studies of hip disorders.
I n a studies carried on thirty four patients MR imaging is the modality of
choice when clinical examination pertaining to suspected patients with disorders
of hip for which plain radiographs are normal or equivocal. Plain radiograph
and MRI study of both hips, unilateral hip involvement was identified in 31
2
patients (91.2%) and bilateral hip involvement was detected in three patients
(8.8%) with a total of 37 hips evaluated by MRI. The final diagnosis in the
patients included reactive arthrititis and early diagnosis and treatment is
important in many of the disorders3.
MR images in 36 hips with documented avascular necrosis and 80 hips
without evidence of joint diseases were studied to determine the amount and
appearance of fluid in the joint. All MRI examinations were carried out on a
1.5T machine and included coronal image made with relative T2 weighting
(repetition ties = 2000-2500 mreco, echo delas=60-100 mreco). The amount of
joint fluid, which had an intense signal higher than that of fat was graded from 0
to 3 and analysed with regards to the patient age and radiographic stage of
avascular necrosis. Therefore, increased joint fluid may be present before
commencement of radiographic abnormalities, but the same is the highest
afterwards flattening of femoral head revealing MRI is a highly sensitive
method for detecting fluid in the hip joint4.
The efficacy of magnetic resonance imaging (MRI) is the assessment of
pediatric hip diseases duly tested by scanning the hips of 24 children ( 30
scans). Twelve patients with Legg-Calve-Perthes diseases (17 hips) showed
characteristic areas of low intensity signal representative of necrotic areas of
the capital epiphysis. The extent of involvement and revascularisation can be
identified in Legg-Calve-Perthes disease5.
The results of magnetic resonance (MR) imaging in six patients with
transient osteoporosis of the hip were reviewed. Short TR/TE (repetion time /
echo time) images demonstrated diffusely decreased signal intensity in the
femoral head and intracapsularregion of the femoral neck. Increased signal
intensity was noted with progressive T2 weighting. Thus, MR scanning can aid
in the diagnosis of transient osteoporosis as the cause of a painful hip6.
3
Magnetic Resonance Imaging (MRI) and conventional radiography were
compared in 49 hips with Avascular Necrosis (AVN). MRI detected AVN in
25% of the hips during the preradiological stage of the disease. Both MRI and
conventional radiographs detected AVN accurately in the remaining 75% of
hips. Minor degrees of collapse of the femoral head were better identified with
plain radiographs but MRI demonstrated small areas of hypersenstivity
probably corresponding to early subchondral fractures7.
MATERIAL AND METHODS
The hip is a stable, major weight-bearing joint with significant mobility.
Hip pain has different etiologies in adults and children. In adults, hip pain may
be caused by intraarticular disorders such as avascular necrosis, arthritis, joint
effusion, tuberculosis and metastatic disease. In children common pathologies
include DDH, Perthe's disease and infections like tuberculosis. Imaging
modalities used to evaluate hip pain and the appropriateness of particular
studies in different clinical scenarios should be considered. The history and
physical examination, play a key role to develop a differential diagnosis prior to
the selection of imaging tests.
Sources of Data :
The main source of data for the study is patients from the following
teaching Hospital attached to Bapuji Education Association, JJM Medical
College, Davangere.
1.
Bapuji Hospital.
2.
Chigateri General Hospital
Appropriate MRI sequences and multiplanar imaging will be performed
for every patient.
4
All patients referred to the department of Radio diagnosis with clinical
history of hip pain during the year 2014 will be subjected for the study.
Inclusion Criteria:
 The study included patients presenting with actue or chronic hip pain.
 Patients of all age groups and both sexes.
Exclusion Criteria:
The study excluded
 Patients with history of acute trauma
 Patient having history of claustrophobia.
 Patient
having
history
of
metallic
implants
insertion,
cardiac
pacemakersand metallic foreign body in situ
Technique:
Imaging was done with 1.5 Tesla Philips Achieva Machine using
abdominal surface coils and spine coils. The following sequences had been
carried out as per selection as required.
a)
TIW coronal - TE (18ms) TR(500-700ms) slice thickness (1-3mm)
b)
TIW axial- TE(18ms) TR(500-700ms) slice thickness (1-3mm)
c)
T2W coronal - TE (100ms) TR (1000-1500ms) slice thickness (1-3mm)
d)
T2W axial - TE(100ms) TR(1000-1500ms) slice thickness (1-3mm)
e)
STIR coronal - TE(30ms) TR(2700-6000ms) slice thickness (3-5 mm)
f)
PD sagittal - TE (30ms) TR (2300-6500ms) slice thickness (3-5mm)
g)
mFFE axial - TE (9.21ms) TR(500 ms) slice thickness (1-3 mm)
5
The study was mainly based on investigation as Radiology itself is a tool
of investigation. The study involved only humans. Informed consent was taken
after explaining about and prior to any procedure.
Ethical clearance has been obtained from the Research and Dissertation
Committee/Ethical Committee of the institution for this study.
RESULTS AND DISCUSSIONS
The complex anatomy of the pelvis and the often subtle but significant
radiographic findings can be challenging to the radiologist. A sound
understanding of the standard radiographic techniques, normal anatomy, and
patterns of disease affecting the pelvis can be helpful in accurate diagnosis8.
Commonly used radiographic projections are, AP view of the hip, an
frog-leg lateral (Dan Miller) view of the hip.
The AP radiograph of this hip (fig.1) is taken with the patient supine, and
both feet in approximately 150 of internal rotation. This reduces the normal 25
to 300 femoral anteversion, allowing better visualisation of the femoral neck9.
The frog leg lateral view (fig.2) is performed with the patient supine, feet
together, and thighs maximally abducted and externally rotated. The
radiographic tube is angled 10 to 150cephalad, directed just above the pubic
symphysis10. The anterior and posterior aspects of the femoral neck, as well as
the lateral aspect of the femoral head, are seen with this projection. The frog leg
lateral view is performed with the patient supine, feet together, and thighs
maximally abducted and externally rotated10. The radiographic tube is angled
10 to 150cephalad, directed just above the pubic symphysis10. The anterior and
posterior aspects of the femoral neck, as well as the lateral aspect of the femoral
head, are seen with this projection.
6
Fig.1: Anteroposterior radiograph of
the pelvis.
Fig.2: Frog-leg lateral radiograph of
the pelvis.
The pelvis is composed of three bones, the ilium, ischium, and pubis, all
of which contribute to the structure of the acetabulum. The ilium is composed of
a body and a large flat portion called the iliac wing11. The body forms with the
bodies of the ischium and pubis, the roof of the acetabulum.
The pubic is composed of a body and two rami 9. The pubic body fuses
with the iliac and ischial bodies to form the anterior border of the acetabulum.
The proximal femur can be divided into the femoral head, femoral neck,
trochanters, and femoral shaft. The fovea is seen at the medial aspect of the
femoral head 11. The femoral head is normally angulated approximately 125 to
1350 with respect to the long axis of the femoral shaft, and anteverted
approximately 25 to 300.11 The major trabeculae of the proximal femur are
well demonstrated on the AP radiograph.9 Long, arc-shaped trabeculae
extending from the femoral head to the intertrochanteric ridge are the principal
tensile trabeculae, which the principal compressive trabeculae are more
vertically oriented, coursing along the medial aspect of the femoral neck.11
7
Fig. 3 : AP radiograph showing major trabeculae
Lines L:
On the standard AP view of the pelvis, the iliopectineal line (also called
the iliopubic line) extends from the medial border of the iliac wing, along the
superior border of the superior pubic ramus9 to end at the pubic symphysis.
This line is seen as the inner margin of the pelvic ring and defines the anterior
column of the pelvis. This line may be thickened in patients with Paget’s
disease12.
The ilioischial line also begins at the medial border of the iliac wing and
extends along the medial border of the ischium9 to end at the ischial tuberosity.
This defines the posterior column of the pelvis.
The anterior rim of the acetabulum is seen as the more medial of two
obliquely oriented arc-shaped lines on the AP view 9. The anterior acetabular
rim is seen well in profile on the 45 degree posterior oblique view 9. the
posterior rim of the acetabulum in the more lateral arc-shaped line on the AP
radiograph and is seen well in profile on the 45 degree anterior oblique view9.
8
The teardrop represents a summation of shadows of the medial acetabular
wall13. Teardrop distance is measured from the lateral edge of the teardrop and
the femoral head. Side-to-side comparison of the teardrop distance can be useful
to evaluate for hip joint effusion or for hip dysplasia13.
Fig.4: AP radiograph of pelvis showing
iliopectineal line (large white arrow)
and ilioischial line (small white arrow)
Fig.5 : The anterior (black arrow) and
posterior (white arrow) walls of the
acetabulum
The iliopectineal line (fig. 4) is part of the anterior column (large white
arrow);
ilioischial line (fig. 4) is part of the posterior column (black arrow),
and teardrop appearance (small white arrow).
The anterior (black arrow) and posterior (white arrow) walls of the
acetabulum (fig.5) are noted.
Line of Kline is a line drawn along the long axis of the superior aspect of
the femoral neck, which normally will intersect the epiphysis.
The Shenton arc is a smooth curvilinear line connecting the medial aspect
of the femoral neck with the undersurface of the superior pubic ramus.
A horizontal line connecting the triradiate cartilages (Hilgenreiner line)
and a perpendicular to this line through the lateral edge of the acetabulum
9
(Perkins line) define four quadrants in which, in normal hips, the femoral head
should be in the lower inner quadrant.
Fat Stripes:
Several fat planes can also be seen on the AP radiograph14. The gluteal
fat stripe (fig. 6) is seen as a straight line paralleling the superior aspect of the
femoral neck on a true AP radiograph and represents normal fat between the
gluteus minimum tendon and the ischiofemoral ligament. This line bulges
superiorly in the presence of a hip joint effusion 14.
The iliopsoas fat stripe (fig.6) is seen as a lucent line immediately inferior
to the iliopsoas tendon. The obturator fat stripe (fig. 6) parallels the iliopectineal
line and is formed by normal pelvic fat adjacent to the obturatorinternus muscle.
Fig .6 : The gluteus minimum fat stripe (small white arrow), obturatorinternus
fat stripe (large white arrow), and iliopsoas fat stripe (black arrow).
MRI OF NORMAL HIP JOINT:
The first decision to make with hip MRI is whether to image both hips
simultaneously or only the symptomatic hip. It is an important decision since it
will influence other decisions such as coil and pulse sequene selection. As a
general guideline, imaging of both hips simultaneously may be appropriate if
10
one is looking for osteonecrosis (given the frequency of bilateral involvement)
or metastasis 15.
When bilateral hip imaging is chosen, the body coil, preferably phase
array, was issued. The following set of pulse sequences is recommended. T1 weighted coronal and fast-spin echo (FSE) T2- weighted or short tau inversion
recovery (STIR) axial. This is done by using a dedicated surface coil, such as a
flexible coil, for better anatomical resolution of small structures such as the
acetabular labrum, or for better evaluation of the articular surfaces or
subchondral area of the femoral head 16.
MRI of the Hip 17. Planes of Imaging to assess anatomy
Coronal :
 Cartilage : suprafoveal head, acetabular dome
 Superior labrum
 Iliofemoral ligament, capsule
 Hip abductors, +/- psoas
Fig. 7: STIR coronal image showing bilateral normal hip joints.
Sagittal:
11
 Cartilage : dome, posterior and suprafoveal bead
 Anterior labrum
 Sciatic nerve
Fig 8: PD sagittal image of normal hip joint
Axial :
 Cartilage : anterior/posterior walls, head, bare area
 Anterior and posterior labrum
 Iliopsoas muscle/tendon
 Sciatic and obturator nerves
12
Fig. 9:T2W axial image showing normal hip joint bilaterally
Bone Marrow:
Yellow / fatty marrow
 T1 hyperintense
 T2 intermediate
Red / hematopoietic marrow
 T1 and T2 intermediate because of higher water content
Fig. 10 : T2W and STIR coronal images demonstrating Conversion to yellow
marrow in apo-/ epiphysis of the femur in 1st year.
13
In the studies which was being carried out both for plain radiography and
MRI consequently consisted of patients complaining of acute and chronic hip
pain. In the cases as being diagnosed as AVN also revealed joint effusion,
osteoarthritis, TB hip, DDH, Perthe's and metastatic diseases to hip joint. Cases
diagnosed revealed that MRI is more sensitive for the detection of AVN even in
early stages where plain radiography displayed normal or subtle findings. MRI
techniques also facilitated in detection of bone marrow old edma but plain
radiography was one restricted to a limited extent. In proven cases of AVN on
plain radiography the MRI facilitated accurate staging of the diseases that
provided an appropriate plan to be executed by the clinician.
Cases diagnosed on plain radiography showed widened tear drop distance
where as cases diagnosed on MRI revealed the higher senstivity of MRI in
detection of joint effusion.
Cases also revealed osteoarthritis both on plain radiography as well as on
MRI, but MRI revealed better delineation of cartilage destruction, accurate
pathological involvement and staging of osteoarthritis.
Cases diagnosed as TB hip, plain radiography established obvious
findings much as Joint space reduction, altered contour of the articular surface,
osteopenia and joint destruction, whereas MRI added a new mile stone towards
findings of the plain X-Ray by detection of minimal joint fluid collection,
hypersensitivity of the articular cartilage which were well detected in the very
early stage of TB Hip. MRI also helped in detection of bone marrow edema,
better delineation of the articular cartilage distruction to a considerable extent
associated with proper delineation of the para articular soft tissue involvement.
Cases which revealed DDH plain were found to be suggestive of X-Ray
imaginary lines like Perkin's line, Hilgenrein's line and shenton's line highly
useful in diagnosing the displacement of epiphyses and dislocation of Hip joint
cases also established Perthe's diseases. Even in Perthe's ailment plain
14
radiography helped to detect the evaluation of cessation of epiphyseal growth in
the form of small ephiphyses. Resorption of femoral head could also be
evaluated. MRI helped indetection of the early stages of DDH and Perthe's by
exposing the involvement of epiphyses in the form of T2W hypersensitivity
before the actual displacement of epiphyses being critically noted. It also helped
in evaluation of bone marrow edema.
Cases also revealed metastatis to the Hip joint. Plain X-Ray helped well
defined osteolytic lesions and also osteoblastic lesions. But, MRI helped in the
evaluation
of the involvement articular cartilage in the form of T2W
hypersensitivity. It also helped in evaluation of soft tissue involvement along
with detection of bone marrow edema.
15
CASE:1
AVSCULAR NECROSIS OF HIP JOINT
A female patient aged 28yrs complaining of left hip pain, clinically suspecting
AVN of left hip joint
Plain X-Ray showing normal hip joints bilaterally
MRI Coronal STIR image showing hyperintense Bone marrow edema involving left femoral
head, neck and intertrochanteric areas. AVN stage 1 – normal radiograph with abnormal MRI
16
CASE 2: TUBERCULOSIS OF HIP JOINT
A 14 yrs old male patient complains of chronic left hip pain, limping gait and
history of fever
Plain xray shows deformative stage of left hip joint with complete dislocation of left hip joint.
MRI coronal STIR image shows dislocation of left hip with pseudoarthosis,
bone marrow edema of femur and acetabular roofassociated with edematous
soft tissue and fluid pockets suggestive of abscess.
17
Case: 3 OSTEOARTHRITIS
A 50 yrs old male patient complaining chronic right hip pain and limping gait.
Plain X Ray shows severe Osteoarthritis with gross reduction of joint space
and deformed femoral head with subchondral cystic changes
MRI SAGITTAL PD and CORONAL STIR images showing loss of articular
cartilage, cytic changes in Subchondral region of femoral head and acetabulum,
severe joint space reduction, irregular contour of femoral head and atrophy of
muscles around hip joint with fatty infiltration
18
Table -1 Sex Distribution
Gender
No. of Patients
%
Male
28
70
Female
12
30
Total
40
100
Graph-1
Sex Distribution
30
Male
Female
70
19
Table -2: Age Wise Distribution
Age
No. of Patients
%
0-10
4
10
11-20
4
10
21-30
8
20
31-40
12
30
41-50
8
20
51-60
2
5
61-70
2
5
Total
40
100%
Graph-2: Age Wise Distribution
14
12
10
8
6
Column1
4
2
0
0-10
20-Nov
21-30
31-40
41-50
51-60
61-70
20
Table: 3 – AVN
AVN
On X-Ray
On M.R.I
Total 12
3(25%)
12(100%)
Graph-3
AVN on X-RAY
25
positive
75
negative
21
Table: 4 – X-Ray Findings
X-Ray Findings
No. of
Patients
Osteoporosis
3
100
Sclerosis
2
66.67
Subchondral Cysts
2
66.67
Crescent Sign/SubchondralLucency
1
33.33
Altered Morphology
1
33.33
% (n=3)
GRAPH 4 : AVN on MRI
POSITIVE
100
22
Table: 5 – M.R.I Findings
M.R.I. Findings
No. of
Patients
% (n=15
Bone Marrow Edema
12
80
Double Line Sign
9
75
Subchondral Cysts
10
66.33
Femoral Head Altered Contour
1
6.67
Femoral Head Fragmentation with Collapse
1
6.67
Out Of 40 Cases 8(20%) Cases Showed Osteoarthritis. All 8 Cases Were
Detected both On Plain Radiography and MRI But Out Of 8 Cases 2(20%)
Cases Showed Stage 1 on X Ray And Stage 2 Or 3 On MRI
Table: 6 TB Hip Joint
TB HIP JOINT
ON X RAY
ON MRI
TOTAL 5
4(80%)
5(100%)
T.B of Hip Joint out of 40 cases 5 cases (12.5%) showed TB HIP 4 (80%)
cases were detected on X-Ray. Whereas 5 cases (100%) cases detected on MRI,
X-Ray. Out of 40 cases 8 (20%) cases showed Osteoarthritis. All the 8 cases
detected both on plain radiography and MRI. But, out of 8 cases 2 (25%)
showed stage 1 on X-Ray stage 2 on MRI
23
CONCLUSION
MRI is an imaging technique that does not require exposure to radiation
and is a valuable tool in the evaluation of hip disorders because it enables
assessment of articular structures, extra articular soft tissues and the osseous
structure that can be affected by hip disease. MRI is becoming increasingly
useful in the diagnosis and management of pediatric hip disorders. MRI is
performed to detect AVN in the early stages thus showing joint effusion and
synovial proliferation can be better identified by MRI compared to conventional
radiography. MRI is extremely sensitive to alterations in the bone marrow that
may represent pathology occult to plain radiography of the hips.
24
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