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5 patients with no primary tumor uptake had uptake in the different sites, and all of the positive and two negative
lymph nodes [Table 2]. lymph nodes. [20]

Mean values for T/Bg index in all patients was 5.44 ± Another study found a higher percentages for sensitivity
1.28 for primary tumor and 4.25 ± 1.67 for lymph nodes. (88%) and specificity (94%). [21] Shiau et al. reported a
[22]
Statistical difference was found with histological grade, 64% sensitivity for 99m Tc-MIBI in primary tumor detection
after categorizing the patients according to their grade, and 73% for tumor recurrence. Shen et al. reported
[15]
[23]
tumor and lymph node size. Thus, concerning histological higher specificity, but lower sensitivity for 99m Tc-TF, as
grade, patients with tumor grades 0 or I had mean values compared to CT. Finally, other researchers suggested that
for 4.5 ± 0.71, whereas patients with tumor grades II or III both 201 Tl and 99m Tc-MIBI have the same accuracies in
had T/Bg indexes of 6.68 ± 0.36. Statistically significant locating primary, recurrent and lymph node involvement
difference between the 2 groups was found (P = 0.034, and thus could also be valuable. [24]
Mann-Whitney U test) [Table 3]. Regarding tumor size,
T/Bg index was lower in tumors < 3 cm (4.05 ± 0.74) than In the study, no relation of the 99m Tc-TF sensitivity with the
in tumors ≥ 3 cm (5.99 ± 0.99). After statistical analysis, pathological grade of the tumor was observed, but there was
there was a trend towards a positive correlation of T/Bg a potential correlation of 99m Tc-TF sensitivity with tumor
index with increasing tumor size (P = 0.053) [Table 3]. size. Thus, it appeared to be a trend toward positive uptake
Mean values for T/Bg index of lymph nodes < 3 cm were with increasing tumor size, which did not reach statistical
2.55, and in lymph nodes ≥ 3 cm, was 3.99 ± 1.5. There significance, probably a result of a relatively small number
was no statistical difference (P = 0.180), possible due to of cases. In contrast, 99m Tc-TF result from previous studies
99m
the small number of cases [Table 3]. No metastatic lesions with Tc-MIBI did correlated tumor size, stage, or histology
were found on whole body images. and it did not affect the tracer uptake. [25] Five patients did
not have any 99m Tc-TF uptake and no tumor was visualized.
DISCUSSION All but one of these tumors had a size < 3 cm and were
in the pharyngeal wall, with close proximity to the tonsils
The study showed as sensitivity of SPECT in pathological and the pyriform fossa. Lower sensitivity in this area could
sites (either primary tumor or regional lymph nodes) of be due to the complex anatomy and physiological uptake,
75%. SPECT sensitivity for only primary tumor diagnosis which make tumor distinction more difficult. Although not
was 58% while for infiltrated lymph nodes it was 57%. verified in the present study, another possibility for negative
In accordance with our findings, a previous study in 10 radiotracer uptake by some tumors could be a possible
patients with nasopharyngeal carcinoma reported the molecular mechanism that pumps the radiopharmaceutical
99m Tc-TF uptake in 7 out of 10 patients (70%). Fattori out of the tumor cells. Such mechanisms attributed
[15]
[26]
et al. studied exclusively patients with laryngeal cancer to membrane multidrug resistance proteins have been
[14]
using 99m Tc-TF and reported 96% sensitivity for detecting associated with resistance to chemotherapy, [27-29] and or
the primary mass and 50% for lymph node involvement. linked to limited or no radiotracer uptake in a variety of
Variations of sensitivities using 99m Tc-TF uptake in primary tumors. [30-33] if this mechanism proves to be significant in
cancers of the head and neck between studies may be head and neck cancers, then the 99m Tc-TF scintigrams may
caused by a small study sample, but it may be higher in be useful in therapy planning for these patients.
patients with exclusively laryngeal cancer according to
other trials. [14] Although the tumor grade was not correlated to radiotracer
uptake sensitivity, it was positively correlated to T/Bg
In another study of 21 patients with nasopharyngeal index. In another study, false-positive cases were reported
carcinoma that evaluated 99m Tc-MIBI, sensitivity was 97% when T/Bg index were ≤ 1.7. In our study, no patient with
[13]
and specificity 100%. A study that compared 99m Tc-MIBI radiotracer uptake had a T/Bg index ≤ 1.7.
[16]
to 99m Tc-TF in nasopharyngeal cancers found that both
radiotracers detected all primary tumors, 99m Tc-MIBI was In conclusion, the study showed that 99m Tc-TF SPECT
superior in detecting pathological lymph nodes (sensitivity had an overall sensitivity for visualization of a head and
95% vs. 79%). The same authors also reported better neck primary cancer site of 58%. However, sensitivity
[13]
sensitivity for 99m Tc-MIBI compared to 201 Tl during was lower for certain tumor locations than others. For
monitoring response to radiotherapy. Similarly, another example, patients with tonsillar and pyriform fossa tumors
[17]
study reported a limited role of 201 Tl in detection of the didn’t have any uptake (false negative exam). Since these
primary tumor with a sensitivity of 54%, specificity 75% sites are difficult to assess, even with SPECT, the results
and accuracy 57%. [18] in these locations should be interpreted with caution.
Generally, SPECT should be accurate for visualization of
In contrast, Wang et al. reported that 201 Tl was more tumors of > 3 cm in any other location. The T/Bg ratio was
[19]
sensitive than 99m Tc-MIBI, with 201 Tl SPECT identifying correlated with malignancy grade. Larger studies will help
94% of the primary lesions in head and neck cancers with to increase the statistic power (as well as comparison with

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Journal of Cancer Metastasis and Treatment ¦ Volume 2 ¦ April 15, 2016 ¦