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