Role of Whole-body Diffusion MR in Detection of Metastatic lesions
Prof. Dr. NAGUI M. ABDELWAHAB,M.D.;
MARYSE Y. AWADALLAH, M.D.
AYA M. BASSAM, Ms.C.
• Cancer is a potentially life-threatening disease, and the
development of skeletal or organ metastases is often
not detected until clinical symptoms present.
• That is why radiological imaging such as plain film X-
ray, Tc99m bone scintigraphy, computed tomography
(CT), positron emission tomography (PET), magnetic
resonance imaging (MRI), are the cornerstone for :-
• Detection and staging of metastatic lesions.
• Classifying their type, site and extent.
• Skeletal scintigraphy is the standard procedure for
visualizing bone metastases, (50-70% of distant
metstases).
• DWI is a powerful imaging tool that provides unique
information related to tumor cellularity, integrity of the cellular
membrane, as well as the movement and functional status of the
microenvironment of water in tissue.
• The technique can be applied widely for tumor detection, tumor
characterization and monitoring of tumor response.
• Until recently, most sensitive radiological procedures
were only limited to local coverage and could not
interrogate the full body.
• Diffusion-weighted sequence (DWI) of the entire body
is a new promising technique feasible to evaluate
multifocal disease.
• Technological advances and the development of the
concept of diffusion-weighted whole-body imaging
with background body signal suppression (DWIBS)
have opened the path for routine clinical whole-body
DWI, which allows detection and characterization of
both oncological and non-oncological lesions
throughout the entire body.
• Several studies stated that; whole body magnetic
resonance imaging (WB-MRI) has shown better
results than skeletal scintigraphy.
• Practical implementation of whole body DWI, using the
DWIBS concept, is relatively easy, since it can be
performed on most modern MRI scanners and does
not require any contrast agent administration.
Furthermore, compared to SPECT/CT and PET CT, MRI
scanners are more widely available and whole body
DWI is less expensive.
To evaluate the value of WB DWI in
detection of metastatic lesions, using
bone scintigraphy for comparison.
• Fifteen patients (5 males and 10 females), referred to the
Radiology department of Kasr Al-Ainy Hospitals from the
outpatient clinic of the Clinical Oncology department, their
ages ranged between 34 to70 years, with known primary
malignant tumor (confirmed histologically) underwent :-
• Whole body MRI including Diffusion weighted Whole body
Imaging with Back ground body signal Suppression (DWIBS),
• Skeletal scintigraphy.
• Any other modality to detect extra-osseous metastases as
computed tomography and ultrasound.
Qualitative analysis was performed directly from the
reformatted images in the coronal plane. Also, the
source images of DWI were revised when required.
WB DWI
The lesions were only categorized according to the
subjectively rated signal pattern, signal intensity and
morphology without taking into account the apparent
diffusion coefficients, which were not quantified.
Malignant lesions generally exhibit considerably greater
signal intensities and variability on their profile than
benign ones.
WB T1-weighted, T2-weighted and STIR images were also
evaluated to combine information, to accurately detect
pathology and rule out artifacts from the diffusion-weighted
sequence series.
The skeletal scintigrams were also analyzed; the increased
uptake pattern of the identified lesions was rated according
to the clinical experience. No quantitative measurements
were considered.
RESULTS
Breast carcinoma (53.3%)
Prostatic carcinoma(13.3%)
Bladder carcinoma(13.3%)
Bronchogenic carcinoma(6.7%)
Thyroid lymphoma(6.7%)
Endometrial carcinoma(6.7%)
RESULTS
Also, it showed the bony lesions detected by bone scan in
the following sites: vertebra, sternum, femur, acetabulum,
humerus, scapula, tibia, shoulder, pelvic bone, greater
trochanter, clavicle, coracoid process & sacrum.
On the other hand, one rib lesion, lesions in skull & lateral
condyle of femur were missed.
RESULTS
The sensitivity of WB DWI in detecting metastatic bony
lesions was 100% with positive predictive value = 94.7%.
The sensitivity of WB DWI in detecting extraosseous
lesions was 100% with positive predictive value = 100%.
Case 1
History and clinical data
Female patient 33 years old who gave history of left modified radical
mastectomy 3 years ago for breast carcinoma.
Pathology:
Invasive ductal carcinoma.
Abdominal ultrasound:
Multiple hepatic focal lesions.
CASES Case 1
Bone Scan
Multiple metastatic osseous lesions involving sternum, head of left femur,
bilateral acetabulum, DV8, LV2, 3, 4 & left 8th rib.
CASES Case 1
WB MRI
Bone metastases: Metastatic osseous lesion of sternum, bilateral acetabulum, head of left
femur, DV8, LV2, 3, 4 & left 8th rib. Soft tissue metastases: Multiple liver metastases.
A B C D E
CASES Case 1
WB MRI
The source axial images with the ADC=1.1 (malignant lesions).
A B
CASES Case 2
History and clinical data
64 years old female patient with history of total thyroidectomy 1 year
ago for thyroid malignancy.
Pathology:
Thyroid lymphoma.
CT chest, abdomen & pelvis:
Multiple metastatic lesions in the liver, both kidneys and right axillary LN.
Case 2 Bone Scan
Multiple infiltrative osseous lesions at sacrum, DV2, 7 & 8 and posterior
segment of left 7th rib.
CASES Case 2
WB MRI
Multiple metastatic lesions in sacrum, DV 2, 7 & 8,
left 7th rib, right axillary lymph node, liver &
bilaterally enlarged kidneys with multiple infiltrations.
The source axial image (ADC=1.0)
A B C D
E
CASES Case 3
History and clinical data
70 years old male patient with history of prostatic carcinoma.
This patient was referred to us for follow up.
CT chest, abdomen & pelvis:
Right apical lung and bilateral suprarenal glands metastases.
Case 3 Bone Scan
Multiple osseous lesions at right scapula, sternum, DV 10, right 9th &
10th ribs & its costovertebral junction and left greater trochanter.
CASES Case 3
WB MRI
The primary malignant lesion is seen (prostatic carcinoma), in addition to multiple metastatic
lesions in the right scapula, left humerus, sternum, DV 10 and its costovertebral junction &
left 9th rib, &, left greater trochanter, AS WELL AS bilateral suprarenal glands metastases &
right apical lung metastases & right 12th rib.
CASES Case 3
WB MRI
A B
C
D
CASES Case 3
Bone Scan
DISCUSSION
In our study whole body diffusion MRI was capable
to detect all extraosseous lesions (23 lesions) and
most of bony lesions (107 lesions). The missed
lesions were 4 lesions (two lesions in the skull, one
in the rib & one in the lateral condyle of the femur).
DISCUSSION
The limitation in detecting rib lesions is due to artifacts that are
related to pulsation and breathing in the thorax, which make
examination of the ribs, sternum and scapula more difficult.
The reason for missed lesions in the skull is unclear, but
may be induced by the interference of high signal in brain.
Red marrow in patients (less than 40 years) causes high SI in DWI this may
explain the missed lateral condyle metastatic lesion in our 38 years old
female pateint by WB DWI.
LIMITATIONS
The sample size was not large
enough for powerful conclusion.
We were unable to perform a biopsy of all skeletal
metastases determined in routine examinations.
The lack of a true gold standard. The standard of
reference we chose was, however, the most effective
method to determine lesions.
Recommendations
The question of whether besides signal enhancement,
quantitative assessment using the ADC values as well would
further improve the results, possibly with threshold values
between malignant and benign metastatic lesions, should be
addressed in future studies.
Larger studies using this WB DWI sequence
should be performed.
Comparing with other whole-body techniques
such as PET/CT is recommended.
TAKE HOME MESSAGE
WB-MRI that included DWI holds great promise,
and has shown utility in the identification of both
bony and visceral metastases. However, more
optimization is required for WB-DWI to become a
routine screening tool, and large-scale studies
are needed to fully gauge its impact in oncology.
WB-MRI