Joint Program in Nuclear Medicine
The Significance of Thallium Uptake in the Scapular Region
Jac D. Scheiner, MD
Annick Van den Abbeele, MD
September 26, 1995
Presentation
A 32 year old male presented with night sweats and abdominal cramping.
Ultrasound showed a mass in the region of the pancreas. Computed tomography
(CT) of the abdomen showed extensive lymphadenopathy in the mesentery and
retroperitonium. An exploratory laparotomy was then performed, along with
mesenteric lymph node biopsies, and a diagnosis of nodular, small cell,
cleaved, malignant lymphoma was made. CT of the chest
(116k bytes) and pelvis was then performed, showing only small bilateral
pleural effusions. Specifically, the scapular regions had a normal appearance.
A bone marrow biopsy was performed, which was negative for lymphoma. The
patient was then discharged without further intervention, given the lack
of significant symptomatology and the low grade of his lymphoma.
Two months later, a whole body thallium planar and single photon emission
computed tomography (SPECT) scan was performed, followed by a whole body
gallium planar and SPECT study
Imaging Technique
All imaging was performed using a Siemens Multispect-2 gamma camera (two
heads).
Thallium Imaging
Planar thallium imaging was performed using the following parameters: dose
= 3 mCi of Tl-201 Chloride intravenously; delay = 20 minutes; collimator
= low energy, high resolution, parallel hole; matrix size = 256 x 256;
images = lateral head (600, 000 counts per view on one side, followed by
the same amount of time on the other side), anterior and posterior chest
(2 million counts per view), anterior and posterior abdomen and pelvis
(1 million counts per view), anterior and posterior femora (image for the
same amount of time as the abdomen and pelvis).
SPECT thallium imaging was performed immediately after planar imaging
using the following parameters: collimator = low energy, high resolution,
parallel hole; matrix size = 64 x 64; orbit = 180 degrees per camera head;
projections = 32 per camera head; time per projection = 60 seconds; images
= nasopharynx to lung bases, followed by lung bases to the pelvis. Processing
parameters: Butterworth filter, 0.6 cycles/pixel critical frequency, alpha
= 1, order = 7, reconstruction planes = axial, sagital , and coronal.
Gallium Imaging
Planar gallium imaging was performed using the following parameters: dose
= 10 mCi of Ga-67 Citrate intravenously; delay = 72 hours; collimator =
medium energy, high resolution, parallel hole; matrix size = 256 x 256;
images = lateral head (600, 000 counts per view on one side, followed by
the same amount of time on the other side), anterior and posterior chest
(2 million counts per view), anterior and posterior abdomen and pelvis
(1 million counts per view), anterior and posterior femora (image for the
same amount of time as the abdomen and pelvis).
SPECT gallium imaging was performed immediately after planar imaging
using the following parameters: collimator = medium energy, high resolution,
parallel hole; matrix size = 64 x 64; orbit = 180 degrees per camera head;
projections = 32 per camera head; time per projection = 50 seconds; images
= nasopharynx to lung bases, followed by lung bases to the pelvis. Processing
parameters: Butterworth filter, 0.6 cycles/pixel critical frequency, alpha
= 1, order = 7, reconstruction planes = axial, sagital , and coronal.
Imaging Findings
The thallium scintigraphy (99k bytes) demonstrated
uptake in the left scapular region (shown by arrow);
the same side as the upper extremity injection. The gallium
scan (83k bytes) demonstrated mild uptake in the abdomen (consistent
with the previously noted CT abnormalities of lymphadenopathy), without
a corresponding scapular region abnormality. Given that the patient's disease
was stable and the patient continued to be asymptomatic, therapy was not
initiated and the patient was observed with close follow-up.
Follow Up
Two months later, a thallium scan (99k bytes) was
performed. The previously noted increased tracer uptake in the left scapular
region was no longer evident. A gallium scan was performed, demonstrating
minimal activity in the sites of patient's known abdominal lymphadenopathy
(decreased from prior exam), without evidence of abnormal scapular region
uptake. A CT of the abdomen and pelvis showed stable retropertioneal and
mesenteric lymph nodes (when compared to the initial CT performed 4 months
ago). A chest x-ray revealed no evidence of active disease. Again, given
the lack of definitive disease progression and lack of patient symptoms,
therapy was not initiated and the patient was observed with close follow-up.
Three months later, a thallium scan (66k bytes)
was performed, which showed increased tracer uptake in the right scapular
region, on the same side of upper extremity thallium injection (shown
by arrow). The gallium scan failed to demonstrate abnormalities in
the right scapular region, and was overall unchanged. The CT of the abdomen
and pelvis demonstrated resolving lymphadenopathy in the mesentery and
retroperitonium. The patient continues to be asymptomatic and is being
closely observed.
Diagnosis
Normal variant
Discussion
Thallium is a radioisotope that acts as a potassium analog. Its primary
mode of cellular uptake is thought to be via a thallium-potassium-sodium
chloride cotransport system, although uptake is also achieved via calcium
dependent ion channels and ATPase pumps (1). It is rapidly cleared from
circulation, and distributes normally at 20 minutes into contracting skeletal
muscle (heart), liver, stomach, small and large bowel, kidneys, thyroid,
salivary glands, testes, and eyes (2). The normal intense uptake in the
liver and colon often limits the usefulness of thallium in the evaluation
of abdominal disease. However, it has proven quite efficacious in the evaluation
of a number of supra-diaphragmatic disease processes. Current uses include
evaluation for pneumocystis carinii pneumonia and pulmonary Kaposi's sarcoma
(3), differentiation of intracranial lymphoma from toxoplasmosis in patients
with acquired immunodeficiency syndrome (4), thymic rebound from recurrent
Hodgkin1s lymphoma (5), and evaluating tumor response to therapy in patients
with sarcomas and brain tumors (6). Thallium may also be more sensitive
for detection of low and intermediate grade non Hodgkin's lymphomas (NHL)
than gallium (7).
In the case presented here, thallium uptake in the scapular region was
noted on two separate occasions. Each time this occurred, the uptake was
on the same side as the upper extremity thallium injection. This uptake
never corresponded to a site of active lymphoma by clinical exam, gallium
scan, or CT. We have noticed this phenomenon of non-pathologic scapular
region uptake in other patients as well.
The etiology of this nonspecific uptake pattern is unknown. It may simply
be a reflection of muscle contraction at the time of thallium administration.
Specifically, the tracer uptake may be in the teres minor, infraspinatus,
supraspinatus, and deltoid muscles , which are normally in a state of contraction
in the abducted, externally rotated arm (8). Uptake in other
patients (99k bytes) has been seen (shown
by arrows) in contracting myocardium (left image), in the sartorius
muscle in a patient twitching his leg (center image), and in the scapular
region in the index case (right image).
Conclusions:
It is important to recognize this characteristic pattern of Tl-201 uptake
in the scapular region on the same side of upper extremity injection, so
as to not misinterpret it as a site of active pathology. Furthermore, should
a patient be suspected of having active disease in the scapular region,
it is important to perform the upper extremity thallium injection on the
contralateral side, so as not to mask true pathology.
References
1. Sessler MJ, Geck P, Maul FD, Hor G, Munz DL. New Aspects of Cellular
Thallium Uptake: Tl-Na-2Cl - Cotransport Is the Central Mechanism of Ion
Uptake. Nucl.Med. 1986; 25:24-27.
2. Krasnow AZ, Collier BD, Isitman AT, Hellman RS, Peck DC. The Clinical
Significance of Unusual Sites of Thallium-201 Uptake. Seminars in Nuclear
Medicine 1988; 18:350-358.
3. Abdel-Dayem HM, Di Fabrizio L, Kowalsky W, et al. Diffuse Thallium
Lung Uptake in Pneumocystis Carinii Pneumonia. Clinical Nuclear Medicine,
Volume 19, Number 4, pp 287-291.
4. O'Malley JP, Ziessman HA, Kumar PN, Harkness BA, Tall JG, Pierce
PF. Diagnosis of Intracranial Lymphoma in Patients with AIDS: Value of
Tl-201 Single Photon Emmision Computed Tomography. AJR 1994; 163:417-421.
5. Harris EW, Rakow JI, Weiner M, Agress H. Thallium-201 Scintigraphy
for Assessment of a Gallium-67 Avid Mediastinal Mass Following Therapy
for Hodgkin's Disease. J Nucl Med 1993; 34:1326-1330.
6. Nadel HR Thallium-201 for Oncological Imaging in Children. Seminars
in Nuclear Medicine 1993; 23:243-254.
7. Kaplan WD, Southee AE, Annese ML, Jochelson MS, Nadler LM. Evaluating
low and intermediate grade non-hodgin's lymphoma with gallium-67 and thallium-201
imaging. J Nucl Med 1990;31:793 (abstr).
8. Snell RS. Clinical Anatomy for Medical Students. 3rd Edition, p.447,
1986.
Click here to go to Joint
Program in Nuclear Medicine home page and Copyright notice.
J. Anthony Parker, MD PhD, Tony_Parker@bidmc.harvard.edu
