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Occult Primary Tumors of the Head and Neck
Accuracy of Thallium 201 Single-Photon Emission Computed Tomography and Computed Tomography and/or Magnetic Resonance Imaging
S. A. J. M. van Veen, MD;
A. J. M. Balm, MD;
R. A. Valdés Olmos, MD;
C. A. Hoefnagel, MD;
F. J. M. Hilgers, MD;
I. B. Tan, MD;
F. A. Pameijer, MD
Arch Otolaryngol Head Neck Surg. 2001;127:406-411.
ABSTRACT
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Objective To determine the accuracy of thallium 201 single-photon emission computed
tomography (thallium SPECT) and computed tomography and/or magnetic resonance
imaging (CT/MRI) in the detection of occult primary tumors of the head and
neck.
Design Study of diagnostic tests.
Setting National Cancer Institute, Amsterdam, the Netherlands.
Patients and Methods Thirty-two patients with a neck node metastasis of an epithelial tumor
and negative findings by mirror examination at initial presentation were included
in the study. Twenty-nine patients underwent thallium SPECT and CT/MRI before
examination under general anesthesia (EUA). In 3 patients only thallium SPECT
was performed before EUA. Histological confirmation of an occult primary tumor
during EUA was used as the gold standard. Negative radiodiagnostic and nuclear
findings in the upper aerodigestive tract in the presence of a primary carcinoma
other than of the head and neck were interpreted as true-negative findings.
Results For thallium SPECT the following results were recorded: sensitivity,
67%; specificity, 69%; accuracy, 69%; positive predictive value, 33%; and
negative predictive value, 90%. In 1 patient, thallium whole body scan indicated
a primary carcinoma beyond the mucosal lining of the upper aerodigestive tract.
The CT/MRI results were as follows: sensitivity, 71%; specificity, 73%; accuracy,
72%; positive predictive value, 45%; and negative predictive value, 89%.
Conclusions Thallium SPECT and CT/MRI showed comparable results for detection of
occult primary tumors of the head and neck. A potential advantage of thallium
SPECT is that it allows total body screening.
INTRODUCTION
PATIENTS WITH squamous cell carcinoma of the head and neck frequently
present with a neck node metastasis as the first symptom. Most primary tumors
are diagnosed during the first routine head and neck evaluation. In a few
cases (1% to 6%), the primary tumor, if present, remains occult after careful
clinical examination, imaging (computed tomography and/or magnetic resonance
imaging [CT/MRI]), and panendoscopy.1, 2, 3, 4, 5, 6, 7, 8, 9, 10
Examination under general anesthesia (EUA) with biopsy specimens of various
head and neck sites at risk and/or tonsillectomy have been recommended for
the detection of the occult primary tumor.10, 11, 12
However, these diagnostic procedures remain relatively inaccurate and are
directed to subsites where occult primary tumors may be expected. Based on
epidemiological evidence, occult primary tumors most frequently occur, in
decreasing order, in the tonsillar fossa, nasopharynx, base of tongue, and
piriform sinus.2, 5, 6, 9, 10, 11
Prebiopsy radiodiagnostic workup may increase the yield of the panendoscopy
by identification of potential biopsy sites. The use of CT/MRI under these
circumstances has increased the detection of occult head and neck primary
tumors.4, 11, 13 On
the other hand, normal radiodiagnostic findings are usually not followed by
positive findings with EUA. In our earlier experience, thallium 201 single-photon
emission CT (thallium SPECT) appeared to be a possible adjunct in detecting
occult primary head and neck tumors.14, 15, 16
To investigate the role of these imaging modalities in the diagnostic workup,
we set up a prospective study of patients presenting with a neck node metastasis
of an unknown primary origin.
PATIENTS AND METHODS
Thirty-two patients with cytologically proven lymph node metastases
from an epithelial tumor were included after negative mirror and/or endoscopic
evaluation results by 2 independent head and neck surgeons (A.J.M.B. and I.B.T.)
between
1995 and 1999. There were 25 men and 7 women, with a median age of 58.3 years
(range, 40-87 years).
Cytological results were as follows: squamous cell carcinomas (n = 20),
undifferentiated carcinomas (n = 9), and adenocarcinomas (n = 3). The distribution
of lymph node metastases among the different levels was as follows: level
I (n = 0), II (n = 26), III (n = 16), IV (n = 6), and V (n = 3).
The CT scan images were obtained with the patient in a supine position
and with quiet respiration (Philips Tomoscan AV; Best, the Netherlands). Contiguous
3- to 5-mm sections were made through the skull base, nasopharynx, oropharynx,
larynx, hypopharynx, and entire neck. The optimal field of view varied between
14 and 18 cm, depending on the size of the patient. Prescanning bolus administration
followed by drip infusion of intravenous (nonionic) contrast medium was used
for all studies.
For MRI studies, a 1.5-T scanner (Siemens Magnetom 63 SP4000; Siemens,
Erlangen, Germany) was used. Section thickness was 4 mm or less, with interslice
gap of 1 mm or less. The optimal field of view for the axial views was 16
to 18 cm for T1-weighted sequences and 18 to 20 cm for T2-weighted sequences.
Intravenous paramagnetic contrast material was injected routinely. T1-weighted
images were obtained before and after injection of intravenous paramagnetic
contrast material. Fourteen patients were studied using MRI, 5 patients with
CT, and 10 patients with both modalities.
A thallium SPECT scan was performed in all patients with the use of
a Vertex dual-head gamma camera (ADAC Laboratories, Milpitas, Calif) equipped
with low-energy, high-resolution collimators 60 minutes after intravenous
injection of 150 MBq of thallous chloride Tl 201. Acquisition was based on
360° noncircular rotation with 6° step angles, 60 seconds per frame,
64 x 64 x 16 matrix, and zoom factor of 1.85 (pixel size, 5 mm).
The images were reconstructed with a Butterworth filter (order 5, cutoff 0.35,
1-pixel images) obtained in the sagittal, coronal, and transverse planes.
Additional 3-dimensional volume reconstructions were used to identify tumor
sites. In addition, simultaneous anterior and posterior planar, 30-minute,
whole body studies (512 x 1024 matrix) were performed just before the
SPECT studies.16
After the imaging procedures, panendoscopy under general anesthesia
was performed with special attention to sites suggestive of carcinoma by CT/MRI
and thallium SPECT. Biopsy specimens were taken from sites suggestive of carcinoma,
and histological proof of the occult primary tumor of the upper aerodigestive
tract was used as the gold standard, meaning that a true-positive finding
represents the histological confirmation of a imaging finding suggestive of
carcinoma. In case of negative imaging findings, nondirected biopsy specimens
were taken from the nasopharynx, tonsil, and base of tongue. Negative radiodiagnostic
and isotope imaging of the upper aerodigestive tract in the presence of a
histologically confirmed primary tumor beyond this area was interpreted as
a true-negative finding. Based on this protocol, sensitivity, specificity,
and accuracy rates were calculated according to the following definitions:
true positive, a; false positive, b; false negative, c; true negative, d;
where sensitivity = a/(a + c); specificity = d/(b + d); accuracy = (a + d)/(a
+ b + c + d); positive predictive value = a/(a + b); and negative predictive
value = d/(c + d).
Rereading of the initial CT/MRI studies and thallium SPECT examinations
by 4 of the authors (S.A.J.M.V.V., A.J.M.B., R.A.V.O., and F.A.P.) was done
for all primary tumors that originated in the mucosal lining of the upper
aerodigestive tract (n = 7) with knowledge of the biopsy-proven primary tumor
site.
RESULTS
A primary site related to the neck node metastasis was identified in
11 patients (34%). Seven primary squamous cell carcinomas originated in the
mucosal lining of the upper aerodigestive tract: nasopharynx (T1), hypopharynx
(T4), supraglottic larynx (T1), tonsillar fossa (T1, T1), and base of tongue
(T1, T2). Furthermore, a primary thyroid carcinoma, a primary carcinoma of
the submandibular gland, a primary gastric carcinoma, and a metastatic bladder
carcinoma, located in the nasopharynx, were found. A bladder carcinoma was
diagnosed and successfully treated 2 years previously in the last patient
(patient 14, Table 1). The T4
hypopharynx carcinoma was a submucosally growing tumor of low volume not seen
at initial ear, nose, and throat examination. Thus, 8 biopsy-proven mucosal
sites in the upper aerodigestive tract were identified. The primary tumor
or metastatic disease were correctly identified by thallium SPECT in 4 of
8 and by CT/MRI in 5 of 8 cases. The imaging findings are summarized in Table 1 and Table 2.
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Table 1. Summary of Imaging Findings in 32 Patients With a Neck Node
Metastasis of Occult Primary Tumor*
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Table 2. Nuclear and Radiodiagnostic Findings for Upper Aerodigestive
Tract*
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The following sensitivity and specificity rates and predictive values
were calculated (Table 3): thallium
SPECT: sensitivity, 67%; specificity, 69%; accuracy, 69%; positive predictive
value, 33%; and negative predictive value, 90%; CT/MRI: sensitivity, 71%;
specificity, 73%; accuracy, 72%; positive predictive value, 45%; and negative
predictive value, 89%. No patient with negative findings on any of the imaging
modalities studied subsequently demonstrated evidence of a primary tumor during
follow-up.
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Table 3. Calculated Values for Thallium SPECT and CT/MRI*
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The results of CT and MRI were similar. Only in 1 of 10 cases was a
discrepancy found. In this case (patient 14, Table 1), CT suggested a primary tumor in the nasopharynx, whereas
MRI was not conclusive due to motion artifacts. For this reason, we excluded
this MRI scan. In 14 patients who were examined with MRI only, the accuracy
rate was 57%. In 5 patients who were examined with CT only, the accuracy rate
was 80%.
The thallium whole body scan detected 1 lesion outside the mucosal lining
of the upper aerodigestive tract. In this case (patient 10, Table 1), an area of increased uptake was found in the right thyroid
lobe. In this patient, thallium SPECT produced a false-positive result for
the aerodigestive tract. The MRI study in this patient produced a true-negative
result for the aerodigestive tract and showed enlargement and pathologic signal
intensity of the right thyroid lobe. This lesion was found to be a primary
thyroid carcinoma. A gastric carcinoma, found at obduction, was not seen on
thallium whole body scan. In patient 11 (Table 1), a carcinoma of the submandibular gland was found after
neck dissection. Both metabolic and radiodiagnostic study results were negative
for a primary tumor.
Rereading with the knowledge of the biopsy-proven primary tumor site
changed the initial reading of thallium SPECT in 1 case. This patient had
a primary tumor in the base of tongue visible on CT and MRI (patient 28, Table 1). The initial reading of the thallium
SPECT study located this lesion in the hypopharynx. In 3 MRI studies, false-positive
(n = 1) and false-negative (n = 2) results changed to true-positive results,
retrospectively (Table 4). In
2 cases (patients 8 and 26, Table 1),
the primary site could only be appreciated retrospectively. In patient 8,
there was minimal asymmetry of the epiglottis ipsilateral to the nodal disease
visible on 1 MRI section. In patient 26, the MRI showed complete symmetry
of the tonsils, but (retrospectively) the side ipsilateral to nodal disease
showed minimal increase in signal intensity. In the third case (patient 1, Table 1), there was a focal mass in the
nasopharynx that was missed at initial reading (ie, reading error).
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Table 4. Summary of Initial Imaging Results and After Rereading With
Knowledge of the Biopsy-Proven Primary Tumor Site*
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COMMENT
Imaging-based detection of clinically occult primary tumors in patients
presenting with a neck node metastasis as the first symptom allows elective
treatment of the primary lesion. Instead of irradiating the laryngopharyngeal
axis, which is the current treatment at many institutions, radiation portals
can be reduced and a higher dose on the primary site may be given, reducing
the treatment-related morbidity caused by wide-field external beam irradiation.1, 5 Panendoscopy has its limitations in
detecting small, superficially growing lesions or submucosal tumors. In current
clinical practice, biopsy specimens are taken from subsites known for harboring
primary lesions, such as the nasopharynx, tonsil, base of tongue, and piriform
sinus.2, 5, 6, 9, 10, 11
To reduce the chance of missing a primary lesion by this approach, imaging
techniques may be of value to indicate areas suggestive of carcinoma. The
use of CT/MRI has been advocated for this purpose.4, 5, 11, 13
In a prospective study of 12 patients with a neck node from unknown primary
squamous cell carcinoma, CT identified a primary occult lesion in 33% of patients.13 In a more recent series, CT/MRI correctly identified
the primary site in 28 (50%) of 56 patients.11
In the present study, the primary tumor (n = 7) or metastatic disease (n =
1) at the mucosal lining of the upper aerodigestive tract was correctly identified
by CT/MRI in 5 of 8 patients. Most of these occult tumors consisted of T1
and T2 lesions (Table 1). One
T4 hypopharynx carcinoma, with a nonbulky submucosal growth pattern, remained
undetected during routine ear, nose, and throat mirror examination. This again
emphasizes the need for careful radiologic and endoscopic evaluation of these
patients, since submucosally growing carcinomas often stay clinically occult
(Figure 1).
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Figure 1. Axial single-photon emission computed
tomogram (SPECT) (A), coronal SPECT (B), axial magnetic resonance image (C),
and coronal short TI inversion recovery (D) of patient 17 demonstrating a
submucosally growing primary tumor in the base of tongue (solid arrows) and
an enlarged lymph node in the left side of the neck (dotted arrows).
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Radiodiagnostic and/or nuclear findings can be helpful in these cases.
However, even when guided by imaging findings, it can still be difficult to
locate the primary site. This was the case in patient 28 with a T1 carcinoma
of the base of tongue undetected at initial routine ear, nose, and throat
examination (Figure 2). Even when
guided by CT/MRI findings, it was still difficult to locate the lesion under
general anesthesia.
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Figure 2. Axial single-photon emission computed
tomogram (A); initial reading located this lesion in the hypopharynx (arrow).
SM indicates submandibular gland. Axial computed tomographic scan (B) demonstrating
a small focal mass in the base of tongue (arrows).
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The efficacy of CT/MRI depends on the use of optimal radiographic techniques.
If imaging is to help identify occult primary tumors, it has to be performed
before endoscopy and biopsy. In prebiopsy imaging, any asymmetric mucosal
thickening ipsilateral to the site of nodal involvement may be suspected of
harboring a primary tumor. In our study, we have mainly used MRI (n = 14)
or the combination of CT and MRI (n = 9, after exclusion of the MRI scan in
patient 14, Table 1). In this
era of cost concern, it seems to be a good principle to do a cross-sectional
study that accurately answers the clinical question for the lowest price.
For evaluation of the head and neck for "suspected unknown primary," several
authors use contrast-enhanced CT as a first choice. In this case, MRI is used
as a supplement for focused evaluation of areas suggestive but not definitively
positive on CT or when CT results are normal.4, 5
Radiodiagnostic imaging will be able to localize or suggest a possible primary
site in about 20% to 50% of cases.4, 5, 11, 13
To our knowledge, there are no firm data available comparing the efficacy
of CT vs MRI in the detection of occult head and neck primary tumors. In the
present study, we found a higher accuracy rate for CT (80%) compared with
MRI (57%). Although the number of examinations is low (MRI, n = 14; CT, n
= 5), these results seem to support the approach suggested by Million et al4 and Mukherji et al.5
Metabolic imaging has been undertaken to improve the detection level of occult
primary tumors.
Fluorine 18–labeled deoxyglucose (FDG) SPECT imaging seems to
have modest value for the detection of occult primary lesions.11
In a series of 18 patients, Mukherji et al found a specificity of 38% for
this technique and a sensitivity of 81%. The authors suggest a complementary
role for FDG SPECT and CT in the detection of occult lesions, increasing the
sensitivity to 91%.5 In a series of 17 patients,
AAssar et al1 suggest a substantial contribution
by FDG positron emission tomography for detection of occult primary tumors.
With this technique, the number of patients with established primary sites
increased to 47% (7/15) compared with 33% (5/15) identified with CT/MRI.1 Similar encouraging results were reported by Braams
et al.17 The results of the aforementioned
studies must be interpreted with caution, because relatively small numbers
of patients were included. AAssar et al1 accept
a small number of false-positive results given the accessibility and minimal
risk of taking biopsy specimens in the head and neck and the importance of
establishing a definitive diagnosis. Compared with other metabolic studies,1, 5, 11 we confirmed a higher
specificity (69%) with an accuracy of 69%. However, the additional value of
thallium SPECT was limited to 1 case in which the MRI result was false positive
(patient 1, Table 1).
In a comparative study on thallium and FDG SPECT in 5 patients with
biopsy-proven squamous cell carcinoma of the head and neck, Mukherji et al18 showed that FDG SPECT had advantages over thallium
SPECT in detecting the primary tumors (5/5 vs 3/5), mainly because of its
reduced salivary gland activity.18 In the present
study, we have not found false-negative results of thallium SPECT due to "masking"
of salivary gland uptake.
A thallium whole body scan has potential value in the detection of occult
primary tumors other than in the head and neck area. In 1 patient, the thallium
whole body scan showed a primary thyroid carcinoma outside the mucosal lining
of the upper aerodigestive tract. In 1 patient, a gastric carcinoma was not
visible on the whole body scan.
Earlier, we stated that normal radiodiagnostic imaging is usually followed
by negative findings with EUA. The high negative predictive value of CT/MRI
(89%) supports this statement. The negative predictive value of thallium SPECT
was 90%, indicating that negative findings with EUA are also very likely after
normal nuclear imaging findings.
Low positive predictive values for both thallium SPECT (33%) and CT/MRI
(45%) were found. This indicates that when panendoscopy shows no macroscopic
abnormality at the site that was indicated by imaging as a possible primary
site, biopsies should always be performed on other sites that are known for
harboring occult primary tumors, ie, nasopharynx, tonsil, base of tongue,
and hypopharynx. Some authors argue in favor of routine ipsilateral (to nodal
disease) or bilateral tonsillectomy in these circumstances.10, 11, 12
On the other hand, the high negative predictive values for both cross-sectional
and nuclear imaging suggest that it is not necessary to repeat a subsequent
negative panendoscopy in this setting.
In this study, thallium SPECT showed comparable results to CT/MRI in
the detection of occult primary lesions. Although thallium SPECT scanning
did not provide better detection of occult head and neck primary tumors in
this study, its role may increase in the future. Potentially, metabolic techniques
can detect subtle mucosal abnormalities not seen on cross-sectional imaging.
In addition, thallium SPECT may reveal the site of the occult primary lesion
in case of false-positive cross-sectional findings (patient 1, Table 1). Future developments in computerized fusion of radiodiagnostic
and metabolic images may help improve localization of radioisotope uptake,19 reducing difficulties in interpreting anatomical
sites (Figure 2). This needs to
be investigated in future prospective correlative studies. For such studies,
we would recommend the algorithm currently used in our institution, based
on the results of the present study (Figure
3). If thallium SPECT is not available, this algorithm (excluding
the metabolic study) can be used in daily practice for imaging analysis of
patients presenting with a neck node metastasis of a squamous cell carcinoma
of unknown origin (Figure 3).
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Figure 3. Algorithm for analysis of patients
presenting with a neck node metastasis of a squamous cell carcinoma of unknown
origin. ENT indicates ear, nose, and throat; CT, computed tomography; MRI,
magnetic resonance imaging; thallium SPECT, thallium 201 single-photon emission
computed tomography; minus sign, negative; and plus sign, positive.
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Rereading of the initial radiodiagnostic studies with knowledge of the
biopsy-proven primary tumor site changed false-negative (n = 2) and false-positive
(n = 1) results to true-positive results in 3 patients. This underscores the
importance of the use of optimal scanning protocols for both CT and MRI. The
reading error in 1 case might have been prevented by double reading. Rereading
of the metabolic studies in these cases changed a false-positive result to
a true-positive result in 1 case (patient 28, Table 1). The hypopharynx, anatomically, is in close proximity to
the base of tongue. It may be difficult to separate these subsites on a thallium
SPECT study. When the cross-sectional studies and the thallium SPECT study
were reread together, it became clear that the location of the increased uptake
on the SPECT study matched the abnormality in the base of tongue seen on CT
and MRI (Figure 2).
In summary, the results of the present study suggest that in the search
for the unknown primary tumor in patients with a cervical metastasis and negative
findings with mirror and/or endoscopic examination at initial presentation,
CT/MRI and thallium SPECT scanning are comparable.
Considering the choice between CT and MRI, the results of the present
study support the approach advocated by several authors, with contrast-enhanced
CT as a first choice. In this case, MRI is used as a supplement for focused
evaluation of areas suggestive but not definitively positive on CT or when
CT results are normal (Figure 3).
When, in addition, a thallium SPECT study is performed, we recommend
simultaneous interpretation of both radiodiagnostic and metabolic studies.
Whole body thallium scan has potential value in the detection of occult primary
tumors beyond the mucosal lining of the upper aerodigestive tract.
AUTHOR INFORMATION
Accepted for publication September 22, 2000.
Presented as a poster at the spring meeting of The Netherlands Society
for Otorhinolaryngology and Cervico-Facial Surgery, Amsterdam, April 22-23,
1999.
From the Departments of Head and Neck Oncology (Drs van Veen, Balm,
Hilgers, and Tan), Nuclear Medicine (Drs Valdés Olmos and Hoefnagel),
and Radiology (Dr Pameijer), The Netherlands Cancer Institute, Antoni van
Leeuwenhoek Hospital, Amsterdam, the Netherlands.
Corresponding author: A. J. M. Balm, MD, The Netherlands Cancer Institute,
Antoni van Leeuwenhoek Hospital, Plesmanlaan 121, 1066 CX Amsterdam, the Netherlands
(e-mail: fbalm{at}nki.nl).
REFERENCES
| |
1. AAssar OS, Fischbein NJ, Caputo GR, et al. Metastatic head and neck cancer: role and usefulness of
FDG PET in locating occult primary tumors. Radiology. 1999;210:177-181.
FREE FULL TEXT
2. De Braud F, Al-Sarraf M. Diagnosis and management of squamous cell carcinoma of unknown primary
tumor site of the neck. Semin Oncol. 1993;20:273-278.
ISI
| PUBMED
3. Jones AS, Cook JA, Phillips DE, Roland NR. Squamous cell carcinoma presenting as an enlarged cervical lymph node. Cancer. 1993;72:1756-1761.
FULL TEXT
|
ISI
| PUBMED
4. Million RR, Cassisi NJ, Mancuso AA. The unknown primary. In: Million RR, Cassisi NJ, eds. Management of
Head and Neck Cancer: A Multidisciplinary Approach. 2nd ed. Philadelphia,
Pa: JB Lippincott; 1994:311-320.
5. Mukherji SK, Drane WE, Mancuso AA, Parsons JT, Mendenhall WM, Stringer S. Occult primary tumors of the head and neck: detection with 2-[F-18]fluoro-2-deoxy-D-glucose
SPECT. Radiology. 1996;199:761-766.
FREE FULL TEXT
6. Lam KH, Lau WF. Metastatic cervical lymph node with an occult primary tumor. In: Aryan S, ed. Cancer of the Head and Neck.
St Louis, Mo: Mosby; 1987:553-559.
7. Nguyen C, Shenouda G, Black MJ, Vuong T, Donath D, Yassa M. Metastatic squamous cell carcinoma to cervical lymph nodes from unknown
primary mucosal sites. Head Neck. 1994;16:58-63.
ISI
| PUBMED
8. Rodriguez J, Bataini JP, Brugere J, Ghossein NA, Jaulerry C. Treatment of metastatic neck nodes secondary to an occult epidermoid
carcinoma of the head and neck. Laryngoscope. 1987;97:1080-1084.
ISI
| PUBMED
9. Oen AL, de Boer MF, Hop WCJ, Knegt P. Cervical metastasis from the unknown primary tumor. Eur Arch Otorhinolaryngol. 1995;252:222-228.
PUBMED
10. McQuone SJ, Eisele DW, Lee DJ, Westra WH, Koch WM. Occult tonsillar carcinoma in the unknown primary. Laryngoscope. 1998;108:1605-1610.
FULL TEXT
|
ISI
| PUBMED
11. Mendenhall WM, Mancuso AA, Parsons JT, Stringer SP, Cassisi NJ. Diagnostic evaluation of squamous cell carcinoma metastatic to cervical
lymph nodes from an unknown head and neck primary site. Head Neck. 1998;20:739-744.
FULL TEXT
|
ISI
| PUBMED
12. Righi PD, Sofferman RA. Screening unilateral tonsillectomy in the unknown primary. Laryngoscope. 1995;105:548-550.
ISI
| PUBMED
13. Muraki AS, Mancuso AA, Harnsberger HR. Metastatic cervical adenopathy from tumors of unknown origin: the role
of CT. Radiology. 1984;152:749-753.
FREE FULL TEXT
14. Gregor RTh, Valdés Olmos R, Koops W, Balm AJ, Hilgers FJ, Hoefnagel CA. Preliminary experience with thallous chloride Tl 201–labeled
single-photon emission computed tomography scanning in head and neck cancer. Arch Otolaryngol Head Neck Surg. 1996;122:509-514.
ABSTRACT
15. Valdés Olmos RA, Balm AJM, Hilgers FJM, et al. Thallium-201 SPECT in the diagnosis of head and neck cancer. J Nucl Med. 1997;38:873-879.
FREE FULL TEXT
16. Valdés Olmos RA, Koops W, Loftus BM, et al. Correlative 201thallium SPECT, MRI and ex vivo 201Tl uptake in detecting and characterizing cervical lymphadenopathy in
head and neck squamous cell carcinoma. J Nucl Med. 1999;40:1414-1419.
FREE FULL TEXT
17. Braams JW, Pruim J, Kole AC, et al. Detection of unknown primary head and neck tumors by positron emission
tomography. Int J Oral Maxillofac Surg. 1997;26:112-115.
ISI
| PUBMED
18. Mukherji SK, Drane WE, Tart RP, Landau S, Mancuso AA. Comparison of thallium-201 and F-18 FDG SPECT uptake in squamous cell
carcinoma of the head and neck. AJNR Am J Neuroradiol. 1994;15:1837-1842.
ABSTRACT
19. de Munck JC, Verster FC, Dubois EA, et al. Registration of MR and SPECT without using external fiducial markers. Phys Med Biol. 1998;43:1255-1269.
FULL TEXT
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ISI
| PUBMED
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