2005 Proceedings - ASNR

Paper 101 Starting at 3:16 PM, Ending at 3:24 PM
Positron Emission Tomography/CT of Cystic Neck
Masses: Trust Your CT
Branstetter,IV, B. F. · Ferris, R.
University of Pittsburgh
Pittsburgh, PA
PURPOSE
Positron emission tomography (PET)/CT has become an
accepted means of staging and monitoring head and neck
cancer. In the setting of a neck mass without a histopathologic
diagnosis, PET/CT also can be useful to distinguish
benign from malignant cases. However, the PET component
of the examination can be misleading in the setting of a cystic
neck mass because the cystic component of the mass will
not have FDG uptake. The purpose of this study is to determine
whether PET/CT is a valuable modality for the evaluation
of cystic neck masses.
MATERIALS & METHODS
Four consecutive patients with cystic neck masses equivocal
for malignancy were included in this study. After equivocal
fine needle aspiration, each patient underwent a combined
PET/CT evaluation. The PET component of each exam was
evaluated by a nuclear medicine physician, and the CT component
was evaluated by a head and neck radiologist; each
had access to the full fused dataset. Discrepancies between
the PET and CT readings were noted and compared to final
pathology.
RESULTS
One of the four patients had a benign branchial cleft cyst,
and three had squamous cell carcinoma. In each of the four
cases, the PET reading was either equivocal or misleading,
whereas the CT reading suggested the correct diagnosis.
CONCLUSION
Before a diagnosis of malignancy has been established, combined
PET/CT of a cystic neck mass is of little value over CT
alone. Cystic lymphadenopathy is evaluated inadequately
with PET alone.
KEY WORDS: PET/CT, neck cyst, neck mass
Paper 102 Starting at 3:24 PM, Ending at 3:32 PM
Role of Apparent Diffusion Coefficient Map in
Differentiating Benign from Malignant Parotid Tumors
Abdel Razek, A. A. · Elhawarey, G. · Albadrawey, A. ·
Elserougy, L. · Kamel, Y.
Mansoura University Faculty of Medicine
Mansoura, EGYPT
PURPOSE
To determine the role of apparent diffusion coefficient map
in differentiating benign from malignant parotid tumors.
MATERIALS & METHODS
This study included 41 patients (21M, 20F aged 10-72 years:
mean 47 years) with parotid mass. They underwent routine
pre and postcontrast MR imaging and diffusion-weighted
imaging on a 1.5 T MR unit (Symphony-Siemens). Diffusion
51
MR imaging was done using spin-echo type of single-shot
echo-planar imaging (EPI) with a diffusion-weighted factor,
factor b of 0.500 and 1000 sec/mm 2 . The apparent diffusion
coefficient (ADC) map was reconstructed. The signal intensity
was assessed visually on ADC maps and ADC value was
measured in parotid lesion. The mean ADC values correlated
with histopathologic results.
RESULTS
Adequate ADC maps were obtained in 39 patients. The
benign tumors shows high SI (n = 23) or mixed SI (n = 4)
and malignant tumors showed low SI (n = 11) or mixed SI (n
= 3). The mean ADC values of benign tumors was 1.49 ±
0.18 X 10 -3 mm 2 /sec and in malignant tumors was 0.89 ± 0.12
X 10 -3 mm 2 /sec. The mean ADC value of the malignant
tumor was significantly different than that of benign parotid
tumors (P < 0.004).
CONCLUSION
Apparent diffusion coefficient map is a new imaging modality
for differentiating benign from malignant parotid tumors.
Also, it can be used for characterization of parotid tumors.
KEY WORDS: Parotid, tumors, diffusion
Paper 103 Starting at 3:32 PM, Ending at 3:40 PM
Role of Apparent Diffusion Coefficient Map in
Differentiating Recurrent Head and Neck Tumors from
Postradiation Changes
Abdel Razek, A. A. · Soliman, N. · Kandeel, A. · Kamel, Y ·
Elshenshawy, H.
Mansoura University Faculty of Medicine
Mansoura, EGYPT
PURPOSE
To evaluate the role of apparent diffusion coefficient (ADC)
map in differentiating recurrent head and neck tumors from
postradiation changes.
MATERIALS & METHODS
This study included 29 patients (21M, 8F aged 53-72 years:
mean 67 years) with suspected clinically recurrent head and
neck tumor after complete course of radiotherapy. Ten of
these patients underwent previous operation. They underwent
routine postcontrast MR imaging. Diffusion-weighted
imaging was done on a 1.5 T whole body scanner
(Symphony, Siemens) using spin-echo type of single-shot
echo-planar imaging. The parameters used were TR/TE:
4200/38 msec, B value = 0, 500 and 1000 sec/mm 2 . From
these images apparent diffusion coefficient (ADC) maps
were generated. The signal intensity was assessed visually
on ADC maps and ADC value was measured in suspected
lesion. The mean ADC values correlated with histopathologic
results. Statistical analysis was done.
RESULTS
Adequate ADC maps were obtained in 28 patients. The
smallest recurrent tumor detected was 1.2 cm. On ADC map,
the recurrent tumor showed low (n = 17) or mixed (n = 4)
signal intensity and postradiation changes revealed relatively
high (n = 5) or mixed (n = 3) signal intensity. The mean
ADC value of the recurrent tumor (1.19 ± 0.23 X 10 -3
mm 2 /sec) was smaller than that of postradiation changes
Monday