OPINION

Magnetic
resonance

• •Imaglng-
Where is it going

to take us?

T here is no doubt that MR pro-
vides a number of capabilities supe-
rior to any other imaging technology
including ultrasonography and CT.
The multiplanar soft tissue contrast,
the wide choice of sequences and its
noninvasiveness have helped propel
the modality into the foreground of
radiological decision making and has
gathered a large number of fervent
followers among our clinical col-
leagues. This trend or momentum, if
you wilt has been dominating the
tenure of the radiological literature
over the last dozen or so years. The
majority of papers in today's litera-
ture still reflect this thinking. It is the
"can do" part of it, as evidenced by
the large volume of technology assess-
ment evaluation studies, that were
and still are bound to become obso-
lete sooner rather than later by the
rapid advances in software technol-
ogy, affecting both MRI and rival
technologies alike.

Nothing, it seems, can dampen
our enthusiasm, or that of our clini-
cal followers. We all strongly believe

A Rijke
Visiting Professor Un/versilf of Natal,
Professor of Radiology, Umverslty of

Virginia, Charlottesville, USA

6 SA JOURNAL OF RADIOLOGY. June 1997

- and I am one of them - that MRI,
particularly that of the CNS and the
musculoskeletal system holds the ulti-
mate capability of uncovering any mor-
phology or pathology needed to direct
therapeutic approach. But will it?

Within a decade of its clinical in-
troduction MRI has become the
imaging test of choice for meniscal
pathology of the knee. Today, MRI of
the menisci is one of the most fre-
quent uses of the technology show-
ing the fibrocartilagic as well as mus-
cle, tendon, and ligament pathology
in exquisite detail reliably dictating
therapy and directing the surgeon to
the site of injury. But does it?

MRI has emerged as the leading
imaging modality for diagnosing asep-
tic necrosis, evaluating soft tissue
masses and staging tumours in the
wrist and ankle. Ongoing improve-
ments in surface coil design have ren-
dered MRI the most powerful tool for
imaging structural abnormalities of
the elbow and shoulder including
numerous disorders that may clini-
cally mimic pathology of the lateral
epicondyle and rotator cuff. For in-
stance, unsuspected ruptures of the
lateral ulnar collateral ligament
(LUCL) or its iatrogenic tearing sec-
ondary overaggressive release of the
common extensor tendon, can be
visualised on MRI and point to subtle
posterolateral elbow destabilisation.
But should it?

The answers to these queries are,
of course, anybody's guess, but it is
worth taking a closer look. They will,
after all, affect us all by determining
nothing less than the future of our
speciality. First then, technological
advancement, particularly in the soft-
ware sector, in the next 10 years or so
is likely to further imaging capability

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Magnetic resonance imaging-
Where is it going to take us?

frompage6

with emphasis on diagnostic and
pathological criteria.

It is, however, far less likely to dic-
tate clinical strategy. There are several
reasons for this. One of them is re-
lated to the inherent shortcomings of
MRI, some of which are euphemisti-
cally referred to as pitfalls, wrongly
suggesting that they can be avoided if
one is aware of them. Other, more
important reasons are to be found in
the area of health care delivery eco-
nomics, patient population base/dy-
namics and of who will be the key
players in the future. It is interesting
to note in this context, that in the last
five years, MRI equipment manufac-
turers have spent a significant part of
their research dollar on the develop-
ment oflow-field permanent magnet
systems as part of both open-configu-
ration and dedicated extremity scan-
ners. Although only two such systems
have so far been approved by the
United States Food and Drug Admin-
istration and only a few are in actual
clinical use today, more are sure to
enter the market place soon. They
offer a number of practical and eco-
nomic advantages including increased
patient comfort and risk at much
lower cost. It is wise to take note of
manufacturers' thinking because they
have a keen eye on future potential
and development. Targeting clinicians
in private practice with affordable
permanent magnet equipment is defi-
nitely on their short-list agenda. And
that will set the stage for who will
image what, in whom and for whom.

Yet another reason why MRI tech-
nology is unlikely to dictate clinical
approach is the concurrent techno-
logical development in other areas of
diagnostic expertise. Arthroscopy is a
case in point: in the same time period
that MR imaging of the internally

deranged knee approached near-per-
fection, the arthroscope has seen ever
so much development in fibroscopic
and manipulative sophistication. Add
to this the capability of intra-articu-
lar excision and reconstruction and
you can see why - economic consid-
erations aside - no orthopaedic sur-
geon would ever let go of this tool,
regardless of what the MR radiolo-
gist may have to offer.

If MRI by itself does not dictate
therapy, it will surely help to direct
the arthroscopist to the site of sus-
pected injury. Well, no, not in prac-
tice, that is: for some anatomical rea-
sons that are not coincidental, those
regions of the knee joint that are most
difficult to visualise by arthroscopy are
also the most difficult to image. It is
only small consolation that injury to
the posterolateral aspect of the lateral
meniscus rarely needs treatment.

The superb imaging capability of
MRI is often the cause of discussion
with clinicians about findings that
mayor may not relate to the patient's
symptoms. One classical example is
spinal stenosis with MRI showing
details of spinal canal bony dimen-
sions and soft tissue alike, often
prompting surgeons to presumptive
conclusions. Another is the continu-
ity of the LUCL in relation to subtle
posterolateral instability. While it is
the radiologist's duty to comment on
the integrity of the LUCL in the con-
text of postoperative elbow imaging,
it is clearly the surgeon's preoperative
understanding of lateral elbow stabi-
lisers that is required to prevent ac-
cidental disruption of this ligament.
In fact, the orthopaedic literature had
documented the significance of the
LUCL in elbow stability well before
this ligament attracted the attention
of MR radiologists.

a SA JOURNAL OF RADIOLOGY. June 1997

So with the technological future
of MRI including three-dimensional
rendering capability foreseeable, the
actual clinical role and how that is
going to be played out and by whom
is far less predictable. One scenario
foreshadows MR radiologists to be
increasingly involved in the depart-
ments of their subspeciality to the
point of joining their faculty/staff as
the imaging specialist. Likely candi-
dates would be neuro-, musculoskel-
etal and cardiothoracic radiologists.
Such developments, while possibly
better serving the imaging require-
ments of clinical departments, would
not fail to severely strain the organi-
sational and administrative capabili-
ties of radiology departments as we
know them today.

Interesting
•Images

At the suggestion of one of our
readers, we will reserve space in the
SA Journal of Radiology for the pub-
lication of interesting cases with the
emphasis on images. The images are
to be of excellent quality in order
to be suitable for publication, and
the publisher reserves the right to
reject any which would not repro-
duce satisfactorily. Pathological pic-
tures are also welcome.

A heading and a brief explana-
tion, together with picture legends,
should accompany the images.

The Editor