Technology insight: PET and PET/CT in head and neck tumor staging and radiation therapy planning

The evolving utilization of functional imaging, mainly 2-[18F]fluoro-2-deoxyglucose (18FDG) imaging, with positron emission tomography (PET) and PET/CT, is profoundly altering head and neck tumor staging approaches, radiation treatment planning, and follow-up management. Tumor-node-metastasis staging with PET/CT has improved the characterization of patient disease versus CT, MRI, or PET alone, thereby affecting patient disease management. Therefore, the utilization of PET/CT is appropriate for head and neck cancer staging in the initial presentation and in the recurrent setting. In the setting of radiation therapy treatment planning, PET-directed tumor volume contouring is not ready for clinical practice without further technological improvements in imaging specificity/sensitivity and resolution. Patient or organ motion might interfere with the accuracy of anatomical co-alignment, and variability in defining the threshold of imaging signals on PET images can affect the contour of the biological tumor volume. The use of PET/CT for staging and detecting both primary and recurrent head and neck cancer is valuable; however, its application in radiation treatment planning should be viewed as investigational.     

What Does PET Imaging Add to Conventional Staging of Head and Neck Cancer Patients?

PURPOSE: To determine the value of PET scans in the staging of patients with head and neck carcinoma. METHODS AND MATERIALS: The charts of 25 patients who underwent neck dissection, computed tomography (CT) scan, and F-18-fluorodeoxyglucose positron emission tomography (FDG-PET) imaging as part of their initial work-up for a head and neck squamous cell cancer between 2000-2003 were reviewed. All patients underwent clinical examination, triple endoscopy, and chest radiograph as part of their clinical staging, adhering to American Joint Commission for Cancer criteria. In addition to the clinical nodal (N) stage, PET findings were incorporated to determine a second type of N staging: clinical N + PET stage. The number of neck sides and nodal levels involved on CT or PET and on pathologic examination were recorded. RESULTS: The sensitivity and specificity for detection of nodal disease were similar for CT and FDG-PET. Positive and negative likelihood ratios were similar for both diagnostic tests. None of our 25 patients had unsuspected distant disease detected by PET. CONCLUSION: The addition of PET imaging did not improve diagnostic accuracy in our patients compared with CT. PET scanning did not alter clinical management in any of the patients.     

Role of PET/CT in Treatment Planning for Head and Neck Cancer Patients Undergoing Definitive Radiotherapy

Background: In this study, we aimed to investigate the benefits of 18F-deoxyglucose positron emissiontomography/computed tomography (FGD-PET/CT) imaging for staging and radiotherapy planning in patientswith head and neck cancer undergoing definitive radiotherapy. Materials and Methods: Thirty-seven headand neck cancer patients who had undergone definitive radiotherapy and PET/CT at the Uludag UniversityMedical Faculty Department of Radiation Oncology were investigated in order to determine the role of PET/CTin staging and radiotherapy planning. Results: The median age of this patient group of 32 males and 5 femaleswas 57 years (13-84years). The stage remained the same in 18 cases, decreased in 5 cases and increased in 14cases with PET/CT imaging. Total gross tumor volume (GTV) determined by CT (GTVCT-Total) was increasedin 32 cases (86.5%) when compared to total GTV determined by PET/CT (GTVPET/CT-Total). The GTV of theprimary tumor determined by PET/CT (GTVPET/CT) was larger in 3 cases and smaller in 34 cases comparedto that determined by CT (GTVCT). The GTV of lymph nodes determined by PET/CT (GTVLNPET/CT) waslarger in 20 cases (54%) and smaller in 12 cases (32.5%) when compared to GTV values determined by CT(GTVLNCT). No pathological lymph nodes were observed in the remaining five cases with both CT and PET/CT. Conclusions: We can conclude that PET/CT can significantly affect both pretreatment staging and assessedtarget tumor volume in patients with head and neck cancer. We therefore recommend examining such cases withPEC/CT before treatment.     

Utility of 18F-fluorodeoxyglucose positron emission tomography in the preoperative staging of squamous cell carcinoma of the oropharynx.

BACKGROUND: 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET) has been reported to be superior to computed tomography (CT)/magnetic resonance imaging (MRI) in the evaluation of head and neck cancers, but little is known about its usefulness in oropharyngeal squamous cell carcinoma (SCC). We therefore compared FDG PET and CT/MRI in the preoperative staging of previously untreated oropharyngeal SCC. METHODS: Thirty-two consecutive patients with oropharyngeal SCC underwent FDG PET and CT/MRI before surgery. Each method was interpreted separately to assess primary tumor and cervical node status. Their sensitivity and specificity were compared relative to histopathologic analysis. RESULTS: Histopathology revealed metastases in 29 of 39 dissected neck sides and in 47 of 163 dissected cervical levels. FDG PET had higher sensitivities than CT/MRI for primary tumor detection (25/32 vs. 30/32, P=0.063) and for identification of cervical metastases on neck side (22/29 vs. 28/29, P<0.05) and level-by-level (37/47 vs. 45/47, P<0.05) bases. In contrast, the specificity of the two methods did not differ significantly (P>0.5). FDG PET correctly interpreted the false-negative results of CT/MRI in 6 of 7 primary tumors and 8 of 10 cervical levels. CONCLUSIONS: The improved preoperative staging of FDG PET may help in planning treatment, but its accuracy is insufficient to replace pathologic staging based on neck dissection.     

Functional imaging in head and neck cancer

Functional imaging has become an increasingly important diagnostic tool for head and neck cancer, and as its availability increases so will its utilization. Positron emission tomography (PET) with the radiotracer 18-fluorodeoxyglucose (¹⁸FDG) is the most commonly used functional imaging technology, and it has the potential to improve the staging and detection of head and neck tumors compared with conventional cross-sectional imaging techniques such as CT or magnetic resonance imaging. Specifically, PET contributes valuable information for localizing a primary tumor in patients with an unknown primary and neck metastasis, in the staging of untreated head and neck cancer, in the detection of residual disease after definitive radiotherapy or chemoradiotherapy, and in the detection of recurrent disease. New technologies have been introduced using the combination of CT and PET, which allows exact anatomic correlation with areas of increased tracer uptake. In addition, new tracers may allow quantification of important cellular processes related to tumor proliferation or identification of tumors that may respond to certain targeted therapies. This strategy will eventually enable physicians to tailor therapy to molecular characteristics and therefore improve outcomes for patients with head and neck cancer.     

The role of PET-CT in the management of patients with advanced cancer of the head and neck

The development of functional imaging using positron emission tomography (PET) has been a major advancement in clinical oncology. In addition, the integration of functional imaging with CT anatomical imaging (PET-CT) has dramatically increased the clinical applicability of PET. This review discusses the current role of PET-CT in head and neck cancer, focusing on its role in staging, detection of unknown primaries, radiotherapy planning, assessment of treatment response, and biological characterization of disease. We also demonstrate why PET-CT should be an integral part of modern management of head and neck cancer.     

Utility of 2-[18F] fluoro-2-deoxy-D-glucose positron emission tomography and positron emission tomography/computed tomography imaging in the preoperative staging of head and neck squamous cell carcinoma

The combination of 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET) and computed tomography (CT) has been reported to be more accurate than CT or PET alone in a preoperative setting. We compared the diagnostic utility of preoperative PET/CT, PET and CT/MRI in 167 patients with newly diagnosed head and neck squamous cell carcinoma (HNSCC), of whom 104 underwent FDG PET and 63 underwent combined PET/CT with all receiving CT/MRI. These preoperative PET, PET/CT, and CT/MRI results were reviewed and their accuracies were compared in patients in whom diagnosis was confirmed histopathologically. Age, sex, primary sites and stage, and nodal involvement were comparable between two groups. The accuracy of PET and PET/CT for detecting primary tumors and cervical metastases was comparable, but significantly higher than that of CT/MRI (98%-97% vs. 86-88% for primary; 92%-93% vs. 85%-86% for neck on a level-by-level basis; P<.05). PET and PET/CT gave false negative results: in 2 (2%) and 2 (3%) patients for primary tumors; in 6 (6%) and 3 (5%) patients for neck metastases, respectively. PET and PET/CT also gave false-positive results for cervical metastases in 5 (5%) and 4 (6%) patients, respectively. Compared with PET alone, preoperative FDG PET/CT may not yield significantly improved diagnostic accuracy in patients with HNSCC. Moreover, despite their high accuracy, PET and PET/CT may not abrogate the need for conventional imaging and pathologic staging based on primary resection and neck dissection.     

18F-脱氧葡萄糖PET判断头颈部癌复发的价值

目的：探讨^18F-脱氧葡萄糖（FDG）正电子发射型体层摄影术（PET）在头颈部癌瘤复发的临床价值。方法：37例头颈部恶性肿瘤，临床疑复发行FDG PET显像（19例全身显像，18例局部显像），其中34例同期行CT或MRI检查，最后诊断依靠病理检查和临床随访。结果：37例患者中FDG PET显像阳性25例，其中3例假阳性；阴性12例，其中假阴性2例。FDG PET显像的敏感性、特异性和准确率分别为91．7％、76．9％和86．5％，CT或MRI检查的分别为68．2％、75．0％和61．8％。在19例FDG PET全身显像中，11例除头颈FDG异常浓聚外，6例还发现有远地转移。结论：评价头颈部癌瘤复发，FDG PET比CT或MRI有更高准确性。     

Imaging of distant metastases of prostate cancer

The detection of distant metastases at the initial diagnosis of prostate cancer (PCa) establishes the treatment approach and has a prognostic value, nevertheless it is not well established. Since proposed staging approaches often contradict each other, we aimed to compare the current imaging techniques for staging of advanced PCa, including future applications of the most innovative methods. Conventional imaging techniques, including computed tomography (CT), magnetic resonance imaging (MRI), and positron emission tomography (PET) have been employed for metastatic staging (both N and M staging) of men with high-risk PCa, but surgical pelvic dissection remains the gold standard for N staging. However, functional MRI by using diffusion-weighted imaging, MR lymphography (MRL) with ultra-small paramagnetic iron oxide particles (USPIO), and hybrid PET/MRI imaging showed both high sensitivity and high specificity for nodal staging and depicting metastases. The standard of practice for M staging in PCa includes the radionuclide bone scan and targeted X-ray film, but their performance has generally been poor. Recently, MRI showed promising results with applications in both local and distant staging. Finally, with the development of new PET tracers, PET/CT and PET/MRI offer a combination of excellent pharmacokinetic characteristics, functional information, and precise anatomic localization and morphological correlation of tumor lesions.     

头颈部淋巴瘤计算机体层摄影、磁共振成像影像特点及临床病理分析

 【摘要】 目的 探讨头颈部结内型及结外型淋巴瘤的计算机体层摄影（CT）与磁共振成像（MRI）影像特点及临床病理特点。方法 分析46例经手术病理或穿刺活检证实的头颈部淋巴瘤患者临床病理及CT、MRI资料,结合文献复习,评价头颈部淋巴瘤的影像特点及临床、病理特点。结果 46例中38例为非霍奇金淋巴瘤（NHL）,8例为霍奇金淋巴瘤（HL）。结外型21例（45.65 %）,包括原发鼻腔10例、咽环（Waldeyer环）7例、喉部2例、甲状腺及腮腺各1例,其中13例伴发颈部淋巴结转移;结内型25例（54.35 %）,主要累及颈部Ⅱ～Ⅳ区淋巴结。Ann Arbor分期：Ⅰ期14例,Ⅱ期19例,Ⅲ期0例,Ⅳ期13例。根据病变形态分为4型：多发结节型25例,肿块型11例,弥漫肿胀型8例,溃疡坏死型2例。结论 头颈部淋巴瘤的CT、MRI影像表现有一定特点,影像检查对淋巴瘤的诊断、鉴别诊断及观察侵犯范围有一定临床价值。     

Random Synchronous Malignancy in Male Breast: A Case Report

We report here a case of a random synchronous male breast malignancy in a patient with a known base of tongue malignancy that was incidentally detected on a whole body 18-fluorine deoxyglucose positron emission tomography and computed tomography (¹⁸F-FDG PET/CT). Patient was referred to us for PET/CT staging and radiotherapy planning for a poorly differentiated squamous cell carcinoma of base of tongue. Histopathologically, the incidentally detected breast lesion was proven to be an invasive ductal carcinoma. ¹⁸F-FDG PET/CT being a whole body imaging modality is known to detect a considerable number of synchronous primaries. Synchronous malignancies in the head and neck area and the upper aerodigestive tract are well established. However, synchronous malignancy in male breast is reportedly uncommon. Our case is unique for the fact that a random synchronous dual malignancy of base of tongue and breast in a male patient was detected during a whole body ¹⁸F-FDG PET/CT imaging.     

What’s New in Imaging for Gynecologic Cancer?

Magnetic resonance imaging (MRI) is the optimal modality for local staging of gynecological tumors. Advances in functional MRI with diffusion-weighted and dynamic contrast-enhanced sequences provide more detailed information regarding tumor cellularity, vascularity, and viability. Fluorodeoxyglucose positron emission tomography/computed tomography (FDG PET/CT) now has an established role in imaging for gynecological cancers, particularly staging of locally advanced cervical cancers and pre-salvage exenterative therapy in relapsed gynecologic tumors. Novel PET tracers, targeting other aspects of tumor biology, are being evaluated although none are currently in routine clinical use. New PET/MR scanners have the potential to combine the strengths of both modalities in one sitting. This review covers advances in gynecologic imaging concentrating on cervical, endometrial, and ovarian cancers.     

Current applications and future developments of positron emission tomography in head and neck cancer]

Positron emission tomography (PET-scan) is a well-established imaging modality in oncology. Using FDG, PET has also a wide range of applications in head and neck tumors for diagnosis, staging, monitoring of response to therapy, and detection of relapse. After a short technical introduction, the current indications of PET-FDG in head and neck tumors are reviewed. Present and future developments of PET are twofold: the use of new tracers for protein synthesis, cellular proliferation or detection of hypoxia etc., and the introduction of metabolic imaging as a adjunct to CT and MRI to determine target-volumes in radiation treatment planning. However, it has to be emphasized that a thorough clinical validation of the methods used is mandatory before their implementation in routine practice.     

Hybrid Imaging in Oncology

In oncology various imaging modalities play a crucial role in diagnosis, staging, restaging, treatment monitoringand follow up of various cancers. Stand-alone morphological imaging like computerized tomography (CT) andmagnetic resonance imaging (MRI) provide a high magnitude of anatomical details about the tumor but arerelatively dumb about tumor physiology. Stand-alone functional imaging like positron emission tomography(PET) and single photon emission tomography (SPECT) are rich in functional information but provide littleinsight into tumor morphology. Introduction of first hybrid modality PET/CT is the one of the most successfulstories of current century which has revolutionized patient care in oncology due to its high diagnostic accuracy.Spurred on by this success, more hybrid imaging modalities like SPECT/CT and PET/MR were introduced. Itis the time to explore the potential applications of the existing hybrid modalities, developing and implementingstandardized imaging protocols and train users in nuclear medicine and radiology. In this review we discussthree existing hybrid modalities with emphasis on their technical aspects and clinical applications in oncology.     

Staging performance of carbon-11 choline positron emission tomography/computed tomography in patients with bone and soft tissue sarcoma: comparison with conventional imaging

The present study was conducted to compare the diagnostic accuracy between carbon-11 choline (11C-choline) positron emission tomography (PET)/computed tomography (CT) and conventional imaging for the staging of bone and soft tissue sarcomas. Sixteen patients who underwent 11C-choline PET/CT prior to treatment were evaluated retrospectively for staging accuracy. Conventional imaging methods consisted of 99,mTc-hydroxymethylene diphosphonate bone scintigraphy, chest CT and magnetic resonance imaging of the primary site. The images were reviewed and a consensus was reached by two board-certified radiologists who were unaware of any clinical or radiological information using hard-copy films and multimodality computer platform. Tumor stage was confirmed by histological examination and/or by an obvious progression in number and/or size of the lesions on follow-up examinations. Reviewers examining both 11C-choline PET/CT and conventional imaging classified T stage in all patients. Interpretation based on 11C-choline PET/CT, the Node (N) stage was correctly diagnosed in all patients, whereas the accuracy of conventional imaging in N stage was 63%. Tumor Node Metastasis (TNM) stage was assessed correctly with 11C-choline PET/CT in 15 of 16 patients (94%) and with conventional imaging in eight of 16 patients (50%). The overall TNM staging and N staging accuracy of 11C-choline PET/CT were significantly higher than that of conventional imaging (P < 0.05). 11C-choline PET/CT is more accurate than conventional imaging regarding clinical staging of patients with bone and soft tissue sarcomas. A whole body 11C-choline PET/CT might be acceptable for imaging studies of tumor staging prior to treatment.     

Combined [18F]fluorodeoxyglucose positron emission tomography and computed tomography for detecting contralateral neck metastases in patients with head and neck squamous cell carcinoma

We evaluated the clinical utility of combined [(18)F]fluorodeoxyglucose (FDG) positron emission tomography (PET) and computed tomography (CT), as well as CT and magnetic resonance imaging (MRI) in identifying nodal metastases in the contralateral neck in patients with head and neck squamous cell carcinoma (HNSCC). A total of 114 patients were preoperatively evaluated with PET/CT and CT/MRI. Histopathologic analysis from bilateral neck dissection tissues was used as the gold standard in assessing these imaging techniques. Of the 114 patients, 63 (55%) had neck metastases and 26 (23%) had contralateral neck metastases. On a per-level basis, FDG PET/CT was significantly more sensitive and accurate than CT/MRI in the ipsilateral (88% vs. 70%, P<0.01 and 93% vs. 89%, P<0.01, respectively) and contralateral (52% vs. 36%, P<0.01 and 91% vs. 90%, P=0.039, respectively) neck. PET/CT and CT/MRI were less sensitive in detecting contralateral than ipsilateral neck metastases due to the lower incidence of metastases and smaller nodes on the contralateral side. Combined PET/CT is superior to CT/MRI in detecting metastatic neck nodes in HNSCC patients. However, PET/CT may not abrogate the need for contralateral neck surgery or radiotherapy in these patients.     

Impact of combined (18)F-FDG PET/CT in head and neck tumours

To compare the interobserver agreement and degree of confidence in anatomical localisation of lesions using 2-[fluorine-18]fluoro-2-deoxy-D-glucose ((18)F-FDG) positron emission tomography (PET)/computed tomography (CT) and (18)F-FDG PET alone in patients with head and neck tumours. A prospective study of 24 patients (16 male, eight female, median age 59 years) with head and neck tumours was undertaken. (18)F-FDG PET/CT was performed for staging purposes. 2D images were acquired over the head and neck area using a GE Discovery LS PET/CT scanner. (18)F-FDG PET images were interpreted by three independent observers. The observers were asked to localise abnormal (18)F-FDG activity to an anatomical territory and score the degree of confidence in localisation on a scale from 1 to 3 (1=exact region unknown; 2=probable; 3=definite). For all (18)F-FDG-avid lesions, standardised uptake values (SUVs) were also calculated. After 3 weeks, the same exercise was carried out using (18)F-FDG PET/CT images, where CT and fused volume data were made available to observers. The degree of interobserver agreement was measured in both instances. A total of six primary lesions with abnormal (18)F-FDG uptake (SUV range 7.2-22) were identified on (18)F-FDG PET alone and on (18)F-FDG PET/CT. In all, 15 nonprimary tumour sites were identified with (18)F-FDG PET only (SUV range 4.5-11.7), while 17 were identified on (18)F-FDG PET/CT. Using (18)F-FDG PET only, correct localisation was documented in three of six primary lesions, while (18)F-FDG PET/CT correctly identified all primary sites. In nonprimary tumour sites, (18)F-FDG PET/CT improved the degree of confidence in anatomical localisation by 51%. Interobserver agreement in assigning primary and nonprimary lesions to anatomical territories was moderate using (18)F-FDG PET alone (kappa coefficients of 0.45 and 0.54, respectively), but almost perfect with (18)F-FDG PET/CT (kappa coefficients of 0.90 and 0.93, respectively). We conclude that (18)F-FDG PET/CT significantly increases interobserver agreement and confidence in disease localisation of (18)F-FDG-avid lesions in patients with head and neck cancers.     

Bildgebung in der Diagnostik des CUP-Syndroms

Diagnostic imaging in patients with CUP (cancer of unknown primary) is aimed at identification of well treatable subgroups, staging (local versus disseminated disease), and early detection of complications in addition to the search for a primary tumor. The basic diagnostic imaging modality is contrast-enhanced whole-body computer tomography (neck to pelvis). Additional PET/CT is recommended as the next step in cases with negative or solitary findings and the possibility for a radical therapy. Mammography, breast sonography and in negative cases breast MRI are recommended for female patients with axillary CUP. In cervical CUP with negative CT or MRI of the neck and thorax, there is strong evidence for PET/CT. Special imaging of the somatostatin receptors is indicated in neuroendocrine metastases with unknown primary.     

The role of PET-CT fusion in head and neck cancer

The fusion of 18-fluorodeoxyglucose (FDG) positron-emission tomography (PET) with computed tomography (CT) offers both anatomic and physiologic delineation of head and neck cancers. PET-CT is useful in the staging of head and neck carcinomas and may identify unsuspected distant metastasis that may alter treatment. PET-CT may also help in target volume delineation during radiotherapy (RT) treatment planning. Better characterization of the target may improve local control as well as spare normal tissues from RT sequelae.     

PET-CT in clinical oncology

Anatomic imaging techniques such as computed tomography (CT) and magnetic resonance imaging (MRI) have been used for many years in clinical oncology. The emergence of positron emission tomography (PET) more than a decade ago was a major breakthrough in the early diagnosis of malignant lesions, as it was based on tumour metabolism and not on anatomy. The merger of both techniques into one thanks to PETCT cameras has made this technology the most important tool in the management of cancer patients. PET/CT with ¹⁸F-FDG is increasingly being used for staging, restaging and treatment monitoring for cancer patients with different types of tumours (lung, breast, colorectal, lymphoma, melanoma, head and neck etc.). At many institutions, PET/CT has replaced separately acquired PET and CT examinations for many oncologic indications. This replacement has occurred despite the fact that only a relatively small number of well designed prospective studies have verified imaging findings against the gold standard of histopathologic tissue evaluation. However, a large number of studies have used acceptable reference standards, such as pathology, imaging and other clinical follow-up findings, for validating PET/CT findings. The impact on the management of patients and the benefits from the information obtained from this anatomo-metabolic procedure justify the term “clinical oncology based on PET-CT” as a new concept to be applied in clinical practice. Supported by an unrestricted educational grant from Roche Farma S.A.