Download Diagnostic Value of Only F-fluorodeocyglucose Positron Emission

Original Research—Head and Neck Surgery
Diagnostic Value of Only
18
F-fluorodeocyglucose Positron Emission
Tomography/Computed Tomography–
Positive Lymph Nodes in Head and Neck
Squamous Cell Carcinoma
Otolaryngology–
Head and Neck Surgery
147(4) 692–698
Ó American Academy of
Otolaryngology—Head and Neck
Surgery Foundation 2012
Reprints and permission:
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DOI: 10.1177/0194599812443040
http://otojournal.org
Sang-Hyuk Lee, MD1, Se-Hyung Huh, MD1, Sung-Min Jin, MD1,
Young-Soo Rho, MD2, Dae-Young Yoon, MD3, and
Chan-Hee Park, MD4
No sponsorships or competing interests have been disclosed for this article.
Abstract
Objective. The role of 18F-fluorodeocyglucose positron emission tomography (PET)/computed tomography (CT) in only
PET/CT–positive lymph nodes (LNs) is not well elucidated
yet. This study was conducted to evaluate the diagnostic
value of only PET/CT–positive LNs without correlating positive findings on conventional imaging modalities (CT, magnetic resonance imaging [MRI], and ultrasound [US]) in
patients with head and neck squamous cell carcinoma
(HNSCC).
Study Design. Case series with chart review.
Setting. Hallym University School of Medicine.
Subjects and Methods. From January 2006 to September
2009, 114 patients with HNSCC who underwent CT, MRI,
US, and PET/CT before definitive surgery with neck dissection were reviewed. All imaging tests were interpreted on
imaging-based nodal classification and were compared with
histopathological findings.
Results. Only PET/CT–positive LNs were found at 48 nodal
levels in 33 patients. Thirteen of 48 (27%) nodal levels were
true-positive (TP), and 35 of 48 (73%) were false-positive
(FP). Fourteen nodal levels were included on N1 necks, and
34 were included on N0 necks. In N0 necks, the FP rate
was significantly higher than the TP rate (28 vs 6, P = .034).
Eleven only PET/CT–positive nodal levels in 10 patients
were found on the contralateral neck side, and FP was significantly more prevalent than TP (8 vs 3, P = .041). No significant difference was observed for mean standardized
uptake value and LN sizes between TP and FP.
Conclusion. Only PET/CT–positive LNs can frequently be
found and do not predict LN metastasis, because a high percentage of results were FP. Our results suggest that only
PET/CT–positive LNs should be considered negative, especially in N0 and contralateral necks.
Keywords
PET/CT, head and neck, lymph node, metastases, squamous
cell carcinoma
Received October 31, 2011; revised January 2, 2012; accepted March
2, 2012.
T
he presence of cervical lymph node (LN) metastases
is one of the most important prognostic factors in
head and neck squamous cell carcinoma (HNSCC).1,2
Therefore, accurate pretreatment staging at the time of diagnosis is critical when selecting an appropriate treatment strategy.3
Assessing cervical LN metastases is extremely difficult clinically. Computed tomography (CT), magnetic resonance imaging (MRI), and ultrasonography (US) are usually used for
preoperative assessment of a primary tumor and cervical LN
status. Recently, positron emission tomography (PET)/CT has
played an increasing role in the diagnosis and management
planning of patients with HNSCC. Many studies have shown
that PET/CT is comparable to, or superior to, conventional
imaging modalities for detecting cervical LN metastases.4-6
A discordant case may occasionally arise between PET/
CT and other conventional imaging modalities (CT, MRI,
1
Department of Otorhinolaryngology-Head & Neck Surgery, Sungkyunkwan
University School of Medicine, Kangbuk Samsung Hospital, Seoul, Korea
2
Department of Otorhinolaryngology–Head and Neck Surgery, Ilsong
Memorial Institute of Head and Neck Cancer, Hallym University Medical
Center, Seoul, Korea
3
Department of Radiology, Hallym University Medical Center, Seoul, Korea
4
Department of Nuclear Medicine, Hallym University Medical Center,
Seoul, Korea
Corresponding Author:
Young-Soo Rho, MD, Department of Otorhinolaryngology–Head and Neck
Surgery, Ilsong Memorial Institute of Head and Neck Cancer, Hallym
University Medical Center, 445 Gil-dong, Kangdong-gu, Seoul, 134-701,
Korea
Email: [email protected]
Lee et al
and US). However, in clinical practice, pretherapeutic imaging is usually interpreted with knowledge of the results of
other modalities.7 The results of CT/MRI/US and PET/CT
appear to be supplementary to each other, and the combined
use of these imaging techniques is particularly useful in
cases with equivocal findings. In a previous study, we
demonstrated that combining CT, MR, US, and PET/CT
improved sensitivity (86.5%) without a loss of specificity
(99.4%) or accuracy (97.0%).7
Nodal necrosis may cause false-negative findings on
PET/CT because of low glycolytic activity of the necrotic
material. CT and MRI imaging can correct false-negative
PET/CT results attributed to small necrotic nodes.8 Falsepositive (FP) PET/CT results may be caused by inflammatory processes in benign LNs. Small nonnecrotic LNs, negative according to CT, MRI, and US criteria, may be positive
on PET/CT imaging. However, the diagnostic role of only a
PET/CT–positive LN is not well elucidated yet. This study
was performed to evaluate the diagnostic value of a PET/
CT–positive LN without correlating positive findings on
conventional imaging modalities in patients with HNSCC.
693
after injecting 2 mL/kg of nonionic contrast medium
(Omnipaque 300, GE Healthcare, Waukesha, Wisconsin;
Utravist 300, Schering, Berlin, Germany) using a detector configuration of 8 3 1.25 mm (ST) or 16 3 0.625 mm (STE),
table speed of 16.75 mm/rot (ST) or 13.5 mm/rot (STE), tube
voltage of 120 kVp, tube current time product of 100 to 300
mAs, slice thickness of 3.75 mm, and image interval of 3.27
mm. All images were acquired in non–breath-hold mode. The
attenuation-corrected PET and enhanced CT images were
reconstructed in the axial, coronal, and sagittal planes with a
slice thickness of 5 mm and fused at the workstation.
Conventional Imaging Modalities
From January 2006 to September 2009, 114 consecutive
patients with HNSCC, who were previously untreated and
underwent CT, MRI, US, and PET/CT within 3 weeks prior
to definitive surgery with neck dissection, were analyzed.
This study protocol was approved by Hallym University
Medical Center institutional review board, and all study participants signed written informed consent.
A diagnosis of squamous cell cancer was made through a
histopathological examination in all patients. Ninety men
and 24 women with a mean age of 59.8 years (range, 21-89
years) were enrolled in this retrospective study. Primary
tumor sites were the oral cavity in 41 patients (36%), oropharynx in 25 (22%), larynx in 25 (22%), hypopharynx in
16 (14%), and other sites in 7 (6%). Surgical and pathological staging of the primary tumors was T1 in 31 patients, T2
in 52, T3 in 25, and T4 in 6.
CT scans of the cervical region were obtained in all patients
with a conventional 16-detector-row CT scanner (MX8000
Infinite Detector Technology; Philips Medical Systems,
Best, The Netherlands) with the following parameters: 3mm section thickness, pitch of 1.5, 4- 3 1.5-mm collimation, 120 kV, and 200 mAs. Contrast material enhancement
was achieved by intravenous administration of 100 mL of
nonionic contrast medium (Omnipaque 300; GE Healthcare,
Princeton, New Jersey) with an injector rate of 2 mL/s.
All patients underwent axial, sagittal, and coronal spinecho T1-weighted MRI imaging (Gyroscan Intera; Philips
Medical Systems; repetition time [TR, ms]/echo time [TE,
ms], 600/10; field of view, 200-300 nm; slice thickness, 6
mm; interslice gap, 1.2-1.8 mm; flap angle, 90°; matrix, 256
æ 256; number of excitations) and 2 axial turbo spin-echo
T2-weighted images (with the same parameters, except for a
TR of 4000 milliseconds and TE of 100 milliseconds).
Furthermore, all patients underwent T1-weighted fatsuppressed imaging after intravenous administration of
gadodiamide (Omniscan; GE Healthcare) at a dose of 0.1
mmol/kg body weight.
US examinations were also performed in all patients with
an HDI 5000 or iU 22 ultrasound unit (Philips Medical
Systems, Bothell, Washington) using a 5- to 15-MHz linear
array transducer. Color Doppler US was performed at a
low-flow setting. A pulse-repetition frequency of 500 to 700
Hz and a low wall filter were used.
PET/CT Technique
Imaging Interpretation
PET/CT was acquired using 2 scanners (Discovery ST or
STE PET/CT; General Electric Medical Systems,
Milwaukee, Wisconsin) after an intravenous injection of
370 to 555 MBq (10-15 mCi) 18F-fluorodeocyglucose (18FFDG) 60 minutes before scanning. Patients had fasted for at
least 6 hours prior to scanning and presented with a blood
glucose level \150 mg/dL.
Patients were scanned from the base of the skull to the
upper thigh, applying a 2- or 3-dimensional mode with a 3minute acquisition per bed position. The PET intrinsic spatial
resolution was 6.1 mm (ST) and 5.1 mm (STE; full width
at half maximum) in the center of the field of view.
Transmission CT and emission PET images were reconstructed using a default vendor-implemented iterative reconstruction algorithm. Enhanced CT was obtained 10 seconds
All imaging tests were interpreted on an imaging-based nodal
classification and were compared with histopathological findings, which served as the reference standard. The neck was
divided into 10 levels (5 bilaterally, I-V), and the analysis was
made on a level-by-level basis. For example, if at least a single
LN met the diagnostic criteria, this was considered positive. All
CT, MR, and US images were interpreted independently by 2
radiologists. To minimize learning bias, CT, MR, and US
images were reviewed in 3 different random orders, and the
reviewing procedure was performed during 3 separate sessions
at 2-week intervals. PET/CT images were interpreted by 1
nuclear medicine physician who also had a certificate of qualification in radiology. Readers were blinded to the results of other
imaging modalities, of each other’s interpretation, and of the
histopathological examination.
Subjects and Methods
Patients
694
Otolaryngology–Head and Neck Surgery 147(4)
Table 1. Diagnostic Criteria for Malignant Lymph Node in CT, MRI, US, and PET/CT
CT, MRI
Maximum axial diameter larger than 15 mm on level I and II, and larger than 10 mm on the other levels
Central necrosis or cystic degeneration
Spherical in shape
Abnormal grouping of 3 or more
US
Short-diameter axis larger than 7 mm
Long-to-short axis ratio smaller than 2.0
Absence of an echogenic hilum
Absence of normal hilar blood flow and/or the presence of abnormal peripheral blood flow on color Doppler imaging
PET/CT
Focal 18F-FDG uptake greater than background activity and corresponding to nodular structures on CT, regardless of lymph node size
Maximum standardized uptake value (maxSUV) no less than 2.5
Abbreviations: CT, computed tomography;
ultrasound.
18
F-FDG,
18
F-fluorodeocyglucose; MRI, magnetic resonance imaging; PET, positron emission tomography; US,
The diagnostic criteria for malignant LNs on CT and MRI
were as follows: (1) maximum axial diameter .15 mm on
level I and II and .10 mm on the other levels, (2) central
necrosis or cystic degeneration, (3) spherical in shape, (4)
and abnormal grouping of 3 or more borderline size LNs.
The diagnostic US criteria were (1) short-diameter axis .7
mm, (2) long-to-short axis ratio \2.0, (3) absence of an
echogenic hilum, and (4) absence of normal hilar blood
flow and/or the presence of abnormal peripheral blood
flow on color Doppler imaging. The diagnostic PET/CT
criteria were (1) focal 18F-FDG uptake greater than background activity and corresponding to nodular structures on
CT, regardless of LN size, and (2) maximum standardized
uptake value (SUV) no less than 2.5. The criteria are summarized in Table 1.
Surgery and Histopathological Examination
Definitive surgery and the neck dissection were performed
according to standard surgical procedures. The type of neck
dissection was determined by the surgeon through clinical
and 3 conventional (CT, MRI, and US) imaging findings.
We defined negative findings on the 3 conventional imaging
modalities as a clinical N0 neck. A modified radical neck
dissection was performed for N1 necks and selective neck
dissection was performed for N0 necks, according to the primary cancer site. Specimens were labeled carefully in the
operating room by the surgeon to allow correlation of histopathological findings with preoperative imaging findings.
All specimens were examined by experienced pathologists,
and the total number of LNs including metastatic LNs at
each level were counted and reported.
Identification of Only PET/CT–Positive LNs and
Statistical Analysis
We classified the LNs that were positive on PET/CT but
negative on other conventional imaging modalities as ‘‘only
PET/CT–positive’’ LNs. We compared preoperative imaging with histopathological findings and calculated the
Figure 1. A case of a true-positive positron emission tomography
(PET)/computed tomography (CT) finding. Only the PET/CT–positive
lymph node with a standard uptake value (SUV) of 3.3 in the right
neck level II (arrow) of a 48-year-old man with right tonsil cancer
proved to be true-positive in the histopathological examination.
sensitivity, specificity, accuracy, negative predictive value
(NPV), and positive predictive value (PPV) for each imaging modality. We compared only the PET/CT–positive
LNs with the histopathological examination and sorted them
as true-positive (TP) LNs (Figure 1) and FP LNs (Figure
2). We also compared only PET/CT–positive LNs according
to surrounding LN status as N0 and N1 necks clinically.
We compared the clinical significance of each category
using the Fisher exact test. Commercially available software
(SPSS version 10.0; SPSS Inc, Chicago, Illinois) was used
for all statistical analyses. A P value \.05 was considered
significantly different.
Lee et al
695
Figure 2. A case of a false-positive positron emission tomography
(PET)/computed tomography (CT) finding. Only a PET/CT–positive
lymph node with a standard uptake value (SUV) of 3.8 in the right
neck level I (arrow) of a 69-year-old woman with right tongue
cancer proved to be true-negative in the histopathological
examination.
Results
A total of 114 patients underwent a neck dissection, and
167 neck sides were dissected (61 unilateral, 53 bilateral)
involving 702 nodal levels. Histopathology revealed nodal
metastases in 79 of 167 neck sides (47.3%) and at 150 of
702 nodal levels (21.4%).
Based on the histopathological examinations, PET/CT
correctly identified LN metastases with a sensitivity of
69.18% and a specificity of 88.67%. We also analyzed the
identification of LN metastases with CT, MRI, and US. CT,
MRI, and US visualized histologically proven LN metastases with a sensitivity of 63.01%, 66.44%, and 65.07% and
with a specificity of 94.06%, 95.32%, and 94.42%, respectively. The sensitivity, specificity, accuracy, PPV, and NPV
of these conventional imaging modalities are summarized
with those of PET/CT in Table 2.
LNs that were positive only on PET/CT but negative on
other conventional imaging modalities (only PET/CT–
positive LNs) were found at 48 nodal levels (7%) in 33
patients (29%) out of 702 nodal levels in 114 patients. The
mean age of patients with only a PET/CT–positive LN was
62.1 years (range, 21-85 years), including 27 men and 6
women. Among the patients with only PET/CT–positive
LNs, 16 primary tumors were localized in the oral cavity, 8
in the oropharynx, 6 in the larynx, 2 in the hypopharynx,
and 1 in the paranasal sinus. The number of dissected nodal
levels along with neck levels in patients with only PET/CT–
positive LNs are compared with all patients in Table 3.
Male-to-female ratio, mean age, and the distribution of primary sites were similar between the 2 groups.
Along with the histopathological examination, 13 of 48
(27%) nodal levels were TP and 35 of 48 (73%) were FP in
only PET/CT–positive LNs. Among the 48 only PET/CT–
positive nodal levels, 14 nodal levels were included in N1
necks and 34 were included in N0 necks. TP and FP were
found equally at 7 levels in each of the N1 necks. But FP
was significantly higher than TP in N0 necks (28 vs 6, P =
.034; Table 4).
Only PET/CT–positive LNs were found mainly on ipsilateral sides, but 11 nodal levels in 10 patients were found
on contralateral sides. In N0 necks, 7 nodal levels were
found on the contralateral side, and all were FP. But in N1
necks, 3 nodal levels were TP and 1 nodal level was FP
among 4 only PET/CT–positive LNs on the contralateral
side (Table 4). The mean SUV of only PET/CT–positive
LNs was 4.2 (range, 2.6-5.3) for TP and 3.2 (range, 2.5-5.7)
for FP. The mean size of only PET/CT–positive LNs was
1.10 (range, 0.46-2.06) for TP and 1.05 (range, 0.46-1.67)
for FP. No significant difference was observed in the mean
SUV or LN size between TP and FP.
Discussion
Radiological imaging modalities such as CT, MRI, and US
have been widely used to assess cervical LN status. These
imaging techniques are comparable with each other for
detecting LN metastases and may detect some occult LN
metastases.9,10 However, the capability of these techniques
to detect small metastatic LNs is limited,11,12 and it is
often difficult to distinguish metastatic from nonmetastatic
reactive LNs because the diagnosis of metastatic lymph
nodes is based mainly on measuring LN size and shape.
Table 2. Sensitivity, Specificity, Accuracy, PPV, and NPV of Each Imaging Modality
Sensitivity (%)
CT
MRI
US
PET/CT
63.01 (54.64-70.85)
66.44 (58.16-74.03)
65.07 (56.75-72.76)
69.18 (61.01-76.55)
Specificity (%)
94.06
95.32
94.42
88.67
(91.77-95.88)
(93.22-96.92)
(92.18-96.18)
(85.74-91.18)
Accuracy (%)
87.61
89.32
88.32
84.62
(85.00-90.21)
(86.90-91.74)
(85.79-90.85)
(81.72-87.52)
PPV (%)
NPV (%)
73.60 (64.97-81.08)
78.86 (70.58-85.70)
75.40 (66.93-82.63)
61.59 (53.68-69.06)
90.64 (87.97-92.89)
91.54 (88.97-93.67)
91.15 (88.52-93.34)
91.64 (88.97-93.83)
Abbreviations: CT, computed tomography; MRI, magnetic resonance imaging; NPV, negative predictive value; PET, positron emission tomography; PPV, positive
predictive value; US, ultrasound.
696
Otolaryngology–Head and Neck Surgery 147(4)
Table 3. Demographics of All Patients Compared with Patients
with Only PET/CT–Positive Lymph Nodes
Number of cases
Total
Only PET/CT–Positive
114 patients,
702 levels
90/24
59.8 (23-89)
33 patients (28.9%),
48 levels (6.8%)
27/6
62.1 (21-85)
Sex, M/F
Age, y, mean (range)
Dissected neck levels (%)
Ipsilateral
I
95 (13.5)
II
114 (16.2)
III
114 (16.2)
IV
105 (15.0)
V
81 (11.5)
Contralateral
I
23 (3.3)
II
54 (7.7)
III
54 (7.7)
IV
46 (6.6)
V
16 (2.3)
Primary site
Oral cavity
41 (36.0)
Oropharynx
25 (21.9)
Larynx
25 (21.9)
Hypopharynx
16 (14.1)
Etc
7 (6.1)
10
20
6
6
1
(20.8)
(41.6)
(12.5)
(12.5)
(2.0)
0
7
3
0
1
(0)
(14.5)
(6.2)
(0)
(2.0)
16
8
6
2
1
(48.5)
(24.2)
(18.2)
(6.1)
(3.0)
Abbreviations: CT, computed tomography; PET, positron emission tomography.
Thus, 18F-FDG PET has been successfully applied to evaluate various kinds of malignancies, including HNSCC.13-15
Growing evidence indicates that 18F-FDG PET imaging is
a very sensitive and valuable imaging tool to evaluate
HNSCC. PET/CT has proven superior to CT or PET alone
for detecting primary and metastatic cancer.5 Previous
studies have described a sensitivity of 91% to 98%, a specificity of 92% to 93%, and an accuracy from 72% to
94%.16-18 PET/CT has become the preferred imaging modality for the diagnosis and management of patients with
HNSCC.
However, PET and PET/CT have potential limitations.
First, false-negative findings may occur in the case of
micrometastases or necrotic LNs. Second, FP findings can
occur in the case of an inflammatory process in the LNs or
spatial inaccuracy because of adjacent metastatic LNs.19-21
Several studies have been reported that overcome these limitations. Ng et al8 showed that the visual correlation of
FDG-PET with CT/MRI is more accurate than FDG-PET
alone for detecting subclinical LN metastases. In 134
patients with oral squamous cell carcinoma, they found a
sensitivity of 51.4%, which increased to 57.1% after visual
correlation with CT/MRI. This increase resulted from the
correction of false-negative 18F-FDG PET results caused by
necrotic nodes and FP 18F-FDG PET results caused by spatial inaccuracy.8
In our study, only PET/CT–positive LNs were found at
48 (6.8%) of 702 nodal levels, and PET/CT was TP at 13
nodal levels (27%) and FP at 35 nodal levels (73%) of 48
only PET/CT–positive LNs. FP was a predominant finding
in N0 necks, which was found at 28 nodal levels (82.4%) of
34 only PET/CT–positive nodal levels, and TP was found at
only 6 nodal levels (17.6%). These results were comparable
with a previous study that evaluated 31 patients with oral
cancer and clinically and radiologically (CT, MRI) negative
necks who underwent 18F-FDG PET/CT before elective
neck dissection. In that study, 12 LN levels were positive
on PET/CT but negative on CT and MRI (8.5%) of 142
nodal levels, and the ratio of FP for PET/CT in only the
PET/CT–positive LNs was also very high (6 neck levels of
12 only PET/CT–positive neck levels, 50%).22
We also analyzed only PET/CT–positive LNs on the contralateral neck sides. Among the 11 total neck levels of only
PET/CT–positive LNs, which were found on the contralateral neck sides, 4 were in N1 necks and 7 were in N0
necks. In N0 necks, all of the only PET/CT–positive LNs
on the contralateral side were FP. We analyzed as to primary site, T stage, and N status in N0 necks, but no correlations were found between contralateral only PET/CT–
positive LNs and the above parameters (Table 5).
18
F-FDG, a glucose analog, is a marker of tumor viability,
based on the observation that malignant cells typically have
higher concentrations of FDG because of increased
Table 4. Number of Only PET/CT–Positive Lymph Node Levels in N1 and N0 Necks Analyzed according to TP and FP Findings
N1 Neck
Ipsilateral
Number of nodal levels
TP
N0 Neck
Contralateral
Ipsilateral
7a
4
FP
P Value
6
3
6
0
28a
7
6
Contralateral
1
21
Abbreviations: CT, computed tomography; FP, false-positive; PET, positron emission tomography; TP, true-positive.
a
P \.05.
7
.034
Lee et al
697
Table 5. Demographics of Patients with Only PET/CT–Positive Lymph Nodes in the Contralateral Neck Sides
No.
Sex
Age, y
Primary Site
T Stage
N Status
TP/FP
Neck Level
1
2
3
4
5
6
7
8
9
10
M
M
M
M
M
M
M
M
M
M
49
69
68
61
52
49
69
64
21
75
Tongue (Rt)
Supraglottis (Rt)
Hypopharynx (Lt)
Maxillary sinus (Rt)
Tonsil (Lt)
Tonsil (Rt)
Supraglottis (Rt)
Mouth floor (Rt)
Tongue (Rt)
Supraglottis (Rt)
T3
T2
T3
T4a
T2
T3
T2
T2
T1
T2
(1)
(1)
(1)
(1)
(–)
(–)
(–)
(–)
(–)
(–)
TP
TP
TP
FP
FP
FP
FP
FP
FP
FP
III
II
III
V
II
II
II
II
II
II, III
Abbreviations: CT, computed tomography; FP, false-positive; PET, positron emission tomography; TP, true-positive.
metabolism and a lack of glycolytic ability.23 The SUV basically describes the concentration of labeled 18F-FDG in
tissue, according to a standard formula. Although institutional
differences may exist for the cutoff value, we used an SUV
.2.5 as highly suspicious for malignancy in this study. In
our previous study using the same SUV reference value, the
sensitivity, specificity, and accuracy of PET/CT were 81.1%,
98.2%, and 95.0%. These results were comparable with other
imaging modalities but without a significant difference.7 This
SUV value was also supported by Fleming and Johansen.24
They evaluated 372 SUV sites in 269 patients with HNSCC
by calculating the accuracy of the SUV when it was changed
from 2.0 to 2.5 and 3.0. The accuracies were almost the same
at 78%, 77.6%, and 77.2%, respectively.24
We had some limitations. In this retrospective study, it was
unclear whether surgically dissected LNs were exactly the same
as those found during the radiological examinations. It is sometimes very difficult to measure aggregated multiple LNs.
However, we analyzed clinical N0 necks with only PET/CT–
positive lymph nodes, so there were no cases of LN aggregation. In contrast, very small LNs that are not detected in preoperative radiological examinations can be difficult to find in
the surgical field, particularly with a retrospective study design.
So, we used the nodal level as the data analysis unit in this
study and also because the surgical treatment for metastatic disease is at the nodal level rather than at an individual node.
Furthermore, for the difficulties to correlate an LN depicted on
an imaging study with the same LN in a neck dissection specimen, correlating imaging results with surgical pathology based
on a level-by-level basis is a more reliable method.
should not affect neck treatment selection. For example,
additional surgical management would not be needed even
if PET/CT detected a positive LN located outside the
planned neck dissection field. In conclusion, our results may
be helpful when assessing LN status in patients with
HNSCC, and only PET/CT–positive LNs would be considered negative, particularly in an N0 neck and on the contralateral side.
Conclusion
Disclosures
Although PET/CT probably has the best accuracy for evaluating LN status in HNSCC, this technique is still not reliable enough to avoid elective treatment of the neck. We
encountered a relatively large number of FP findings in
only PET/CT–positive LNs, and the FP findings found in
N0 necks and on the contralateral side were statistically significant. Management of the neck should not be based on
PET/CT findings alone, and only PET/CT–positive LNs
Competing interests: None.
Acknowledgments
We acknowledge the resident surgeons, nurses, anesthesiologist,
pathologists, and radiologists who assisted us in performing surgeries and in reviewing and analyzing the surgical, pathological,
and radiological records.
Author Contributions
Sang-Hyuk Lee, patient care including operation and postoperative
management, data collection and analysis, reviewing articles, editing, and final approval of the article to be submitted; Se-Hyung
Huh, patient care including postoperative management, data collection and analysis, chart review, reviewing articles, editing, and final
approval of the article to be submitted; Sung-Min Jin, patient care
including operation and postoperative management, data collection
and analysis, and final approval of the article to be submitted;
Young-Soo Rho, patient care including preoperative evaluation,
operation (operator of all cases in this study), study design, reviewing articles, editing, and final approval of the article to be submitted;
Dae-Young Yoon, radiologic evaluation (CT, MRI, and US), data
analysis, editing, and final approval of the article to be submitted;
Chan-Hee Park, PET/CT evaluation, data analysis, editing, and
final approval of the article to be submitted.
Sponsorships: None.
Funding source: None.
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