Color-coded duplex sonography showed nearly equal results to CT scan in primary tumor detection but was better in recurrent carcinoma. The demonstration of the local vascularization pattern by this method helped to identify lesions not found by CT. A major disadvantage is the fact that not all regions of interest are accessible. Infratemporal and pterygopalatinal fossa, skull base, parts of the parapharyngeal space, nasopharynx, hypopharyx, and the larynx cannot be sonographically investigated, in part or whole.
This is a serious limitation for a more general use of the procedure. Some authors 5 , 10 reported good results of CCDS. Hence, the application of CCDS was of limited value only for the detection of a primary tumor site. Although we do not consider CCDS the procedure of choice for the identification of all primary tumor sites in the head and neck, we routinely apply it for this purpose while we search for suspected lymph nodes.
From our experience, CCDS occasionally can provide useful supplementary information about a suspected tumor site. Despite the progress and refinement of various imaging procedures, panendoscopy is still a valuable diagnostic procedure for the detection of tumors in the upper aerodigestive tract and cannot be replaced by any imaging procedure tested in this study. Early mucosal lesions, often undetected or overlooked by all imaging procedures applied here could be successfully demonstrated by panendoscopy. The higher figures for false-positive results in panendoscopy in recurrent disease depend in part on the experience of the clinician.
After therapeutic treatment, it can be difficult in some instances with panendoscopy, too, to distinguish scarring from a recurrent carcinoma. The results in the detection of nodal neck metastases differ from those obtained in the comparison of primary tumor lesions.
In neck imaging all procedures showed exactly the same sensitivity. As expected, the palpation was significantly less sensitive. Various studies demonstrated that leukocytes have a high glucose utilization and, therefore, store high amounts of 18 FDG. In CCDS, lymph nodes larger than 10 mm or problems in the demonstration of the vascularization pattern yielded false-positive results. False-negative results occurred in patients with lymph nodes smaller than 10 mm and unsuspicious shape and in patients in whom depiction of vascularization was uncertain. The results of the our study show that panendoscopy is still a first-choice procedure for the detection of primary tumor and recurrent carcinomas in the head and neck region.
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Particularly for the detection of recurrent carcinoma after irradiation and surgery, PET was the most reliable imaging procedure in this study. Owing to its limited anatomical depiction, functional imaging cannot replace morphologic-based imaging procedures such as CT or magnetic resonance imaging in the planning of the therapeutic procedure at the moment.
Advanced technology that provides better resolution of the PET scans might help to solve this problem in the future. At present, the most promising strategy is to combine the advantages of both procedures by coregistration of PET imaging with CT or magnetic resonance imaging. This approach can efficiently support a more reliable localization of a malignancy suspected in PET. Computed tomography and, to a more limited extent, CCDS have their place in the detection and evaluation of the local spread in suspected tumor localization.
Our study demonstrated that for routine evaluation of lymph nodes in the neck, CCDS is a first-choice procedure. Tracer uptake values failed to prove significant correlation to the tumor grading in this study. Because of the high costs, PET is not a part of the standard diagnostic program and is limited to specialized medical centers at the moment. All Rights Reserved. Table 1. View Large Download. Primary and Recurrent Tumor Diagnoses in 50 Patients. J Otolaryngol. Otolaryngol Head Neck Surg. Head Neck. Eur J Nucl Med. Hematol Oncol Clin North Am. Otorhinolaryngol Nova. J Oral Maxillofac Surg.
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Am J Otolaryngol. Can we detect or predict the presence of occult nodal metastases in patients with squamous carcinoma of the oral tongue? Computer-assisted three-dimensional reconstruction of head and neck tumors. Thallium single-photon emission CT versus CT for the detection of recurrent squamous cell carcinoma of the head and neck. Detection of recurrent head and neck squamous cell carcinomas after radiation therapy with F-fluoro 2-deoxy-D-glucose positron emission tomography. PET scanning in head and neck oncology: a review.
Use of positron emission tomography with fluorodeoxyglucose in patients with extracranial head and neck cancers. The role of positron emission tomography in occult primary head and neck cancers. Cancer J Sci Am. Detection of unknow occult primary tumors using positron emission tomography.
Change induced by radiation therapy in FDG uptake in normal and malignant structures of the head and neck: quantition with PET. Prediction of survival with fluorinefluoro-deoxyglucose and PET in head and neck cancer. J Nucl Med.
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Noninvasive imaging biomarkers can play a crucial role in assessment of the entire tumor sample and can be repeated longitudinally to monitor treatment response, and guide decision-making process. Diffusion MRI can assess cellular density and cytoarchitecture based on the measurement of water diffusivity. For the purpose of diffusion MRI, two strong opposed gradient pulses are applied along a certain diffusion direction, with the first diffusion-sensitizing gradient dephasing the water molecules, and the second gradient completely rephasing the stationary molecules.
Such a signal intensity decrease depends on the degree of molecule movement and respective speed along the diffusion-sensitizing gradient, as well as the strength of the gradient itself, and the duration of the diffusion-encoding gradients b-value 6 , 7.
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Thus, diffusion abnormalities of water molecules, captured by DWI, can reflect changes of tissue organization and impediments in water molecule motion at a cellular level. The b-values are defined by the gradient strength, duration, and the time interval between the gradient pulses 8. Mono- and biexponential models can be used for quantifying the diffusion 9.
However, while fast-moving water molecules quickly lose their phase coherence and signal intensity, even at low b-values, slow-moving molecules will retain high signal intensities far into the higher ranges of b-values Thus, mono-exponential ADC values cannot separate pure molecular diffusion from motion of water molecules in the capillary network; whereas, multi-exponential models using several b-values are more suitable for accurate quantification of diffusion without perfusion contamination 10 , For biexponential models, the metrics related to IVIM for each b-value are calculated using 12 :.
In DKI, multiple b-values are applied to assess the extent to which the diffusion pattern of water molecules deviates from a perfect Gaussian curve that is assumed when calculating monoexponential ADC values 14 :. There are limited number of studies examining the optimal combination and number of b-values for IVIM.
Lemke et al. However, Gurney-Champion et al. Sasaki et al. Noij et al. Regarding the fit model used for estimation of diffusion parameters, the majority of studies listed in Table 1 have applied bi-exponential with Levenberg Marquard algorithm for the IVIM fit—with the exception of Dikaios et al. The SS-EPI is relatively insensitive to motion but prone to susceptibility artifacts, chemical shift, and geometric distortion, with a limited spatial resolution and relatively thick sections Compared to SS-EPI, turbo spin echo technique requires longer echo time but less susceptibility artifacts and better spatial resolution The SS version of turbo spin echo is a diffusion-weighted HASTE sequence with lower sensitivity to motion and susceptibility artifacts as well as geometric distortion compared to the EPI sequence Overall, the non-echo planar diffusion can improve image quality with lower susceptibility artifacts and higher spatial resolution; however, they non-EPI DWI scans take longer to acquire which can introduce more motions and have lower signal-to-noise ratio, which requires multiple averages and prolongs scanning time Hence, non-echo planar diffusion is usually reserved for problem solving rather than routine clinical practice.
Tissue sampling and pathologic examination remain the gold standard for assessing the malignant nature of a head and neck lesion; however, tissue biopsy is not without risk, and cannot examine the whole lesion. Multiple studies have demonstrated the ability and reliability of quantitative diffusion MRI in distinction of benign from malignant lesions and differentiation of different HNT Although there are many factors affecting the ADC, it is generally accepted that the ADC of a given voxel is inversely proportional to the cellularity of the tissue included in that voxel, and malignant tumors likely demonstrate lower ADC values compared with benign lesions owing to their relatively higher cellularity.
Some authors have focused on distinction of malignant from benign lesions using average ADC values. Using a 1. They found cysts to have higher mean ADC 2. Quantitative diffusion MRI can also help with differentiation of various histopathologies; for example, differentiation of various salivary gland lesions.
Accurate preoperative differentiation of a salivary gland tumor is important in establishing the surgical indication and preoperative planning. While the majority of salivary gland tumors are benign either pleomorphic adenomas or Warthin tumors , some can be malignant adenoid cystic carcinoma or mucoepidermoid carcinoma. Prior studies suggest that pleomorphic adenomas which contain myxoid tissue have the highest ADC; whereas, Warthin tumors which contain lymphoid tissue have the lowest ADC values Ikeda et al.
And Kikuchi et al. Quantitative diffusion MRI can also help with differentiation between benign and malignant thyroid nodules, with latter showing lower average ADC values 6. Similarly, using a 1. Nodal metastases herald poor prognosis in patients with head and neck cancer, and their detection is important for treatment planning, extent of radiation treatment field, or surgical neck dissection method.
Currently, the differentiation of metastatic lymphadenopathy primarily relies on size criteria; however, nonenlarged nodes may harbor malignancy, and reactive nodes may be prominently enlarged In addition, in patients presenting with suspicious cervical lymphadenopathy, differentiation of lymphoma from metastatic lymph nodes of unknown primary cancer site can be challenging. Distinction of metastatic from lymphomatous lymphadenopathy is particularly crucial since they demand radically different treatment approaches.
Quantitative diffusion MRI can help with distinction of these entities. Table 2 summarizes the results of studies comparing non-malignant, metastatic, and lymphomatous lymph nodes in head and neck 46 - Except for Sumi et al. On the other hand, Hejduk et al. Abdel Razek et al.
Holzapfel et al. For distinction of lymphomatous from metastatic lymphadenopathy, Zhang et al. They proposed an ADC value threshold of 0. The classical description of HPV-positive oropharyngeal cancer histology is non-keratinizing and basaloid differentiated SCC as opposed to keratinizing and poorly differentiated form which is commonly seen with HPV-negative forms Chan et al.
Nakahira et al. This is particularly important since distinction of HPV status dictates the cancer staging and treatment strategy in patients with oropharyngeal SCC In addition to prediction of HPV status, some studies have shown the application of quantitative diffusion MRI in evaluation of HNT microstructure and histopathological characteristics.
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