Haematologica 2003 - Supplements

Standard Radiology – is an important baseline. Approximately
75% of patients with myeloma bone disease will manifest lytic
lesions and/or osteopenia with or without fractures on x-ray (1).
Other Imaging Techniques – such as MRI, CT-scanning,
FDG/PET and 99m Tc-MIBI are additionally helpful, in a
complementary fashion, both overall and especially in the 25% of
patients with negative x-rays, to establish the presence, location
and activity of myeloma lesions. Particular advantages are:
MRI – This is the most reliable technique to document the
anatomic distribution of myeloma lesions (2-5). MRI is useful
both if x-rays are negative and/or if specific clinical problems
require delineation, e.g., neurologic compromise, pain. The
practical problem is how to perform MRI of the whole body.
Although we have developed a wide field screening technique for
this, it remains cumbersome and expensive.
CT Scanning – This is very helpful for detailed evaluation of
localized sites of disease, especially to evaluate bone destruction
and/or in preparation for radiation therapy (6).
We have therefore evaluated the additional benefit of whole body
FDG/PET scanning. (7) The purpose of this evaluation was to
assess the clinical utility of whole body positron emission
tomography with [ 18 F] fluorodeoxyglucose (FDG/PET) in
patients with multiple myeloma and related monoclonal diseases,
such as MGUS and solitary plasmacytoma.
Methods: Between July 1, 1996 and December 2001, 84 patients
underwent 122 FDG/PET scans with 34 patients having 2 or more
scans. Results were compared with routine clinical and staging
information including MRI and CT scans, as indicated. Of the 84
patients: 21 had previously untreated active myeloma, 16 had
monoclonal gammopathy of undetermined significance (MGUS),
13 were in remission and 34 had relapsing disease.
Results: Negative whole body FDG/PET reliably predicted stable
MGUS. Of the 16 MGUS patients with follow-up of 3-55+
months, only 1 (6%) has developed myeloma at 8 months.
Conversely, the 21 previously untreated (PU) patients with active
myeloma all had focal and/or diffusely positive scans. 5/21 (24%)
PU patients with positive FDG/PET scans had negative full
radiologic surveys. Another 5/21 (24%) patients had focal extra
medullary disease. This was confirmed by biopsy and/or other
imaging techniques. Extra medullary uptake also occurred in 8/34
(23%) relapse patients. This extra medullary uptake was a very
poor prognostic factor both pretreatment and at relapse: e.g.,
median survival 7 months for relapsing patients. Persistent
positive FDG/PET post induction therapy and/or stem cell
transplantation predicted early relapse. 13/16 (81%) relapsing
patients had new sites of disease identified. The FDG/PET scan
results were especially helpful in identifying focal recurrent
disease in patients with nonsecretory or hyposecretory disease
amenable to local irradiation therapy used in 6 patients. Serum
Freelite testing is being cross correlated with serial FDG/PET
imaging. Serum Freelite levels > 200mg/L correlate with discrete
changes on FDG/PET.
Conclusions: Whole body FDG/PET imaging provides important
staging and prognostic information, which reliably identifies
active myeloma versus MGUS. FDG/PET also identifies poor
risk patients pretreatment and the potential for early relapse post
induction and/or stem cell transplantation. Identification of focal
relapse in nonsecretory patients is especially helpful. Formal cost
effectiveness analysis is recommended.
Prior to our investigations of the role of 18F-FDG PET (2), we
and others had evaluated the role of 99m Tc-MIBI (8-11). The
new question is: what are the relative merits of 99m Tc-MIBI
versus 18F-FDG PET? From an ongoing comparative analysis
with serial 99m Tc-MIBI scanning, a few comments can be made.
Both are positive in approximately 25% of patients with negative
radiographs. Both can give helpful prognostic information. Since
multi-drug resistant, p-glycoprotein positive myeloma is negative
with 99m Tc-MIBI and FDG/PET is positive, there is differential
utility in this setting (10). Both 99m Tc-MIBI and FDG/PET are
usually negative in MGUS. However, slow growing, smoldering
or asymptomatic myeloma can be positive with 99m Tc-MIBI,
often in the form of a diffuse marrow “superscan” effect (11).
FDG/PET is much better for detection and monitoring of discrete
sites of more rapidly growing active myeloma both within bone
and in extra medullary sites. The detection of lesions, especially
“hot spot” foci, is enhanced by tomographic nuclear medicine
techniques. PET offers the advantage of being a whole body,
tomographic study and can often detect lesions not seen with
planar (non tomographic) imaging. SPECT MIBI may be helpful
in selected sites. The unpredictable GI activity as well as other
abdominal organ uptake is a disadvantage for MIBI compared to
FDG-PET. Our results have been much more favorable with
FDG-PET in the lower spine and pelvis regions. Nonetheless, it is
very helpful to have two nuclear imaging techniques capable of
providing different types of clinical information and correlations.
Overall, having several complementary imaging techniques with
excellent results gives greater flexibility in evaluating patients
with myeloma.
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