With proper planning and technique, a complete musculoskeletal magnetic resonance examination can be accomplished with three pulse sequences. The efficient protocols presented in this article reduce time and costs, while addressing specific areas of concern and the suspected pathology.
Dr. Seeger is a Professor and Chief of Musculoskeletal
Imaging in the Department of Radiological Sciences at UCLA
School of Medicine, Los Angeles, CA.
In the current climate of reduced reimbursement for imaging
studies, streamlining image acquisition is essential. Gone are the
luxury days when one could leave the patient on the scanner table
for an hour, acquiring multiple pulse sequences. One must now
consider time: scanner time, technologist time, and physician time.
The use of intravenous (IV) contrast increases scan time, and may
or may not be reimbursable. Extra imaging also increases the cost
of supplies, such as film. To be profitable, we must improve
Under most circumstances, a complete musculoskeletal magnetic
resonance (MR) examination can be accomplished with three pulse
sequences. To set the protocols, one needs to be aware of the
anatomy to be evaluated and the suspected pathology. If more than
three sequences are done, consider what additional information you
will get from this scan, as your equipment and personnel are likely
not being utilized to maximum capacity.
Joint specific protocols
The protocols outlined below should serve as guidelines only.
Variations on the pulse sequences are certainly acceptable without
compromising the information that can be extracted from the scan.
The important message is the use of a maximum of three sequences.
The inclusion of a fat-suppressed T2 and/or inversion-recovery
sequence is important regardless of the area under investigation.
Usually, the fat-suppressed T2 sequence will show anatomic detail
better than an inversion recovery scan will. The latter may,
however, be useful for determining the presence of very subtle
marrow or soft-tissue changes.
A complete knee study consists of a sagittal double echo, coronal
double echo, and axial fat-suppressed T2 scan. This allows
evaluation of the menisci in 3 planes, the cruciate ligaments in 2,
and the collateral ligaments in 2. The articular cartilage of all 3
compartments is demonstrated well. The patellar retinaculum is
evident on the axial images, and fat suppression provides sensitive
identification of subtle marrow changes.
A routine shoulder study consists of a coronal oblique double echo,
sagittal oblique fat-suppressed T2, and axial double echo or
2D-gradient echoes scan. The rotator cuff is visible in 2 planes,
the biceps tendon can be seen within the intertubercular sulcus and
at its anchor, and the labrum is seen circumferentially. The
acromioclavicular and glenohumeral joints are displayed well, and
acromial morphology can be evaluated in 2 planes.
A sagittal T1, axial double echo, and coronal fat-suppressed T2
scan will show all important ankle anatomy. The major medial,
lateral, and anterior tendons are seen best on the axial images,
and the Achilles tendon is seen well in 2 planes. The lateral
ligaments are demonstrated on both the axial and coronal scans. All
3 planes are useful for detecting osteochondral lesions. The sinus
tarsi and spring ligament can also be evaluated.
Unless very high-resolution images of a specific part of the bony
pelvis or proximal femur are needed, scans should include both
hips, the sacrum, and the pubic symphysis, from the iliac crests to
the proximal femoral shafts. Since a large proportion of hip MR
studies are looking for fracture, tumor, or avascular necrosis, it
is useful to image the entire pelvis to detect lesions that would
otherwise be missed. The study can be accomplished with a coronal
T1, coronal inversion-recovery, and axial fat-suppressed T2
When searching for radiographically occult traumatic lesions of
long bones (tibia, metatarsal, etc.), the scan should be coned to
the area of clinical concern to provide high-resolution images. The
technologist should put skin markers at the proximal and distal
area of pain, and use an appropriate surface coil. A longitudinal
T1 and inversion-recovery scan, and an axial fat-suppressed T2 scan
will show all pertinent findings, including marrow and soft-tissue
edema, periostitis, and cortical infractions.
Most centers have established protocols for routine MR imaging
of joints and the spine, but when faced with an extremity mass or
tumor, excessive steps may be undertaken to compensate for
diagnostic uncertainty. It is, therefore, important to establish an
approach to MR image acquisition and analysis of nonarticular
extremity lesions, and to understand both the strengths and the
limitations of MRI.
Most musculoskeletal tumors can be imaged adequately with a
maximum of 3 pulse sequences: T1-weighted spin echo, fat-suppressed
T2, and inversion recovery. The optimal imaging plane will depend
on the location of the lesion.
The T1-weighted scan may be in the axial plane in the case of a
soft-tissue mass, and should be confined to the mass itself. If a
bone lesion is being evaluated, the T1-weighted scan should be in a
longitudinal orientation using a large field-of-view. With bone
lesions, the purpose of the T1 scan is to evaluate the entire
length of bone involvement, provide measurements for surgery, and
detect skip lesions. An oblique orientation should be used, if
needed, to include the entire bone with both proximal and distal
joints on one large field-of view scan whenever possible.
For soft-tissue and bone tumors, a fat-suppressed T2-weighted
scan should be acquired in the axial plane. Fat suppression will
differentiate between tumor and normal intermuscular, subcutaneous,
or marrow fat. The scan should be coned to the lesion, using a
surface coil, if appropriate, and scanning to normal tissue above
and below. This sequence will allow localization of any soft-tissue
mass around the circumference of the bone and compartmental
localization of a soft-tissue mass; it will also determine the
relationship of the mass to surrounding muscles and assess any
involvement of a joint or major neurovascular structures.
Periostitis can also be seen.
While most important information can be obtained from these 2
sequences, the addition of a longitudinal inversion recovery scan
may complement the study. For bone lesions, the purpose of this
scan is to again assess the extent of marrow involvement and
evaluate the extent of periostitis or soft-tissue mass that may
extend proximal or distal to the marrow involvement. This may alter
surgical margins, extending the area of resection. The scan should
be acquired with an oblique orientation if needed, and coned to the
Most often, MR imaging for infection is requested to evaluate
for osteomyelitis. T1-weighted spin echo, fat-suppressed T2, and
inversion-recovery sequences are adequate. The imaging planes will
be determined by the location of the clinical pathology, and it is
important to be aware of the presence of any skin ulceration or
areas of induration. This often requires communication with the
technologist after the patient has arrived, as specific information
regarding the area of abnormality is usually lacking on the
Usually, IV contrast administration does not add clinically
useful information to the MR diagnosis of musculoskeletal lesions.
It cannot be used to differentiate benign masses from malignancy,
does not improve the accuracy of tumor staging, cannot
differentiate peritumoral edema from tumor infiltration, and, with
the rare exception of soft-tissue desmoid, does not improve lesion
conspicuity over that available with fat-suppressed T2-weighted
scans. The marrow edema of osteomyelitis will enhance
nonspecifically. Enhancement characteristics such as intensity and
homogeneity reflect nonspecific characteristics of any lesion
including vascularity, vascular permeability, and the size of the
extracellular fluid compartment. Gadolinium (Gd) may, in fact,
partially obscure margins of any focal abnormality, as it may
increase the signal of a lesion to equal that of normal fat. If Gd
is to be used, post-contrast T1-weighted scans should utilize
Possible uses for contrast administration include
differentiation of viable versus cystic or necrotic tumor to guide
percutaneous biopsy, identification or documentation of
postoperative seroma, and localization of soft-tissue abscesses.
Most fluid collections are, however, evident on nonenhanced
Dynamic image acquisition following IV Gd administration has
been suggested for tumor-specific diagnosis, differentiation of
tumor from peritumoral edema, and evaluation of tumor response to
preoperative chemotherapy. This is a time-consuming and costly
technique in terms of personnel, scanner time, contrast material,
and post-processing. It has been studied extensively in Europe but
has not gained clinical popularity in the U.S., where it is
generally considered to be an investigational technique.
Efficiency in MR imaging is now essential. While imaging the
musculoskeletal system involves the possibility of innumerable body
parts and possible pathologic processes, a diagnostic scan can be
accomplished in a time-efficient manner by using only three
sequences and omitting the use of IV Gd. In order to sequence any
scan properly, one needs to be aware of the specific area of
concern and the suspected pathology. If needed, this information
can be relayed to the physician by the technologist at the time of