Imaging in head and neck cancer

Opinion statement The goals of imaging in head and neck cancer are to establish tumor extent and size, to assess nodal disease, to evaluate for perineural tumor spread, and to distinguish recurrent tumor from post-treatment changes. MRI is the preferred modality for assessment of nasopharyngeal, sinonasal, and parotid tumors, because of better contrast resolution, high frequency of perineural spread, and less prominent motion artifacts. MRI is the best modality to delineate the extent of intraorbital and intracranial extension of malignant tumors. Tumors of the oropharynx, larynx, and hypopharynx are frequently primarily imaged with CT, which is less affected by breathing and swallowing artifacts. MRI is also the initial study of choice for tumors confined to the oral tongue, and possibly also for other oral cavity locations because MRI is superior in detection of tumor spread into the bone marrow. There is no clear advantage of CT or MRI for evaluation of nodal disease. Positron emission tomography (PET) is very sensitive for metastatic lymph nodes that are at least 8 mm in size and is the technique of choice in dubious cases. Imaging-guided biopsies are performed whenever needed. For imaging of treated head and neck cancer, PET scans have been found to generally offer higher sensitivity than MRI or CT. Combined PET/CT may be the modality of choice because it almost completely eliminates the false-positive and false-negative PET findings. Patients with head and neck cancer who are referred to tertiary care centers commonly arrive with cross-sectional images obtained at other institutions. Reinterpretation of these studies by dedicated radiologists frequently leads to changes in findings, which alter treatment and affect prognosis.     

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.     

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.     

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.     

Diagnostic imaging in the follow-up of recurrent cervical carcinoma

The follow-up of a patient with recurrent cervical carcinoma treated with intracavitary radiotherapy and brachytherapy is reported. The role of CT and MRI was analyzed. MRI is considered the procedure of choice in follow-up. In the future, total body PET will probably play a major role in the detection of recurrence in patients with cervical cancer.     

Advances in imaging in the postoperative patient with a rising prostate-specific antigen level

Imaging prostate cancer continues to represent a clinical challenge for both primary and recurrent disease. In the evaluation of the persistent/recurrent/metastatic prostate cancer, knowledge of cancer location (local v distant), size, and extent are essential in order to design a treatment, tailored to each patient's needs. There are evidence-based guidelines for the use of imaging in assessing the presence of distant spread of prostate cancer. Radionuclide bone scans and computed tomography (CT), magnetic resonance imaging (MRI), and/or positron emission tomography (PET) supplement clinical and biochemical evaluations (prostate-specific antigen [PSA]) for suspected metastatic disease to bones and lymph nodes. There is no consensus about the use of imaging in the evaluation of local tumor recurrence. The use of ultrasound has been limited to biopsy guidance of the prostatic bed, or percutaneous biopsy of enlarged lymph nodes detected on CT or MRI. The use of MRI is evolving. Recent studies indicate that the use of MRI provides valuable information in the evaluation of local tumor recurrence, and nodal and bony metastases. In a patient post-radiation therapy, the method of combining MRI anatomic information with MR spectroscopic metabolic information is evolving. Another modality offering information about anatomy and metabolism of the local disease is PET/CT. The value of PET/CT at present is controversial, but new studies exploring the role of PET/CT in aggressive prostate cancer are promising.     

The usefulness of MRI and PET imaging for the detection of parametrial involvement and lymph node metastasis in patients with cervical cancer

OBJECTIVE: The purpose of this study is to elucidate the usefulness of magnetic resonance imaging (MRI) and positron emission tomography (PET) for the detection of parametrial involvement and lymph node metastasis in patients with cervical cancer. METHODS: Thirty-six patients with cervical cancer were retrospectively enrolled. MRI and PET scans were performed for all patients within a week before radical surgery. The criterion for malignancy on MRI was >1 cm short axis diameter of the suspected lymph node. On PET, only fluorodeoxyglucose (FDG) uptake was significantly higher than the background and, if this FDG uptake showed on at least two consecutive axial slices, then the lesion was considered as a malignancy. We compared the extent of tumor on the surgical findings with the FIGO staging, MRI and PET scans. RESULTS: The accuracy of FIGO and MRI staging was 67 and 84.4%, respectively. The accuracy for detecting pelvic lymph node metastasis was better for PET than for MRI (78 versus 67%, respectively). All FDG uptake lymph nodes were confirmed as metastatic lymph nodes by pathological evaluation; this included five lymph nodes <1 cm in diameter. CONCLUSION: MRI provides an improved evaluation of local tumor extension, but PET is more useful for the evaluation of pelvic lymph nodes than MRI; however, PET still misses microscopic disease. Further studies are necessary to evaluate the usefulness of PET/computed tomography (CT) for the accuracy of the disease extension and the cost-effectiveness of MRI, PET or PET/CT in patients with cervical cancer.     

Literature review: Imaging in prostate cancer

Imaging plays an increasingly important role in the detection and characterization of prostate cancer (PC). This review summarizes the key conventional and advanced imaging modalities including multiparametric magnetic resonance imaging (MRI) and positron emission tomography (PET) imaging and tries to instruct clinicians in finding the best image modality depending on the patient`s PC-stage. We aim to give an overview of the different image modalities and their benefits and weaknesses in imaging PC.Emphasis is put on primary prostate cancer detection and staging as well as on recurrent and castration resistant prostate cancer. Results from studies using various imaging techniques are discussed and compared. For the different stages of PC, advantages and disadvantages of the different imaging modalities are discussed. Moreover, this review aims to give an outlook about upcoming, new imaging modalities and how they might be implemented in the future into clinical routine.Imaging patients suffering from PC should aim for exact diagnosis, accurate detection of PC lesions and should mirror the true tumor burden. Imaging should lead to the best patient treatment available in the current PC-stage and should avoid unnecessary therapeutic interventions. New image modalities such as long axial field of view PET/CT with photon-counting CT and radiopharmaceuticals like androgen receptor targeting radiopharmaceuticals open up new possibilities. In conclusion, PC imaging is growing and each image modality is aiming for improvement.     

^18F-FDGPET／CT显像对宫颈癌诊断及治疗的影响

目的研究^18F-FDGPET／CT显像在宫颈癌诊断、分期及指导治疗方面的应用价值。方法88例患者行腹部或全身^18F-FDGPET／CT显像,其中初诊者30例（宫颈良性病变11例,宫颈癌19例）,宫颈癌治疗后58例。病灶确诊根据病理结果、多种影像诊断技术及临床随访而定,随访时间均大于6个月。结果30例初诊者PET／CT诊断宫颈癌的灵敏度、特异性和准确性分别为89．5％,90．9％和90．0％。58例治疗后患者中,11例存在肿瘤复发或残余,PET／CT诊断肿瘤复发、残余的灵敏度、特异性和准确性分别为90．9％,100．0％和98．3％。41例有肿瘤转移,PET／CT诊断转移灶的灵敏度、特异性和准确性分别为92．7％,88．9％和90．9％。77例宫颈癌患者中26．8％PET／CT发现直径小于1．0cm的小淋巴结转移灶、28．6％因PET／CT发现腹腔外远处转移灶而提高了临床分期,32．4％患者因PET／CT显像而改变和修改了原治疗方案。18例输尿管梗阻患者中,16例PET／CT发现为肿瘤侵犯压迫所致而促使临床及时地进行了输尿管内置管,减少了肾功能的损害。结论^18F-FDGPET／CT显像可提高宫颈癌诊断准确性,使治疗方案的制定更科学。     

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.     

Szintigraphie und Single-Photon-Emissions-Computertomographie (SPECT und PET)

Planar scintigraphy and single photon emission computed tomography (SPECT) or SPECT/computed tomography (CT) still play an important role in oncology, particularly in the detection of skeletal metastases, in thyroid cancer, in neuroendocrine tumours, and for imaging of the lymphatic system involved in drainage of the tumour area. Positron emission tomography (PET) or PET/CT has become an established modality in the management of many tumours. By far, the glucose analogue fluorodeoxyglucose (FDG) is the most frequently used radiotracer, used mainly for staging and detection of recurrences. Because inflammatory processes may be associated with increased glucose utilisation, bioptic confirmation of PET-positive findings may be required. For less dedifferentiated tumours, non-FDG PET tracers are increasingly employed, such as for prostate cancer and neuroendocrine tumours.     

New directions in head and neck imaging

Computerized tomography (CT) and magnetic resonance imaging (MRI), positron emission tomography (PET) and the hybrid modality of PET/CT are sensitive and reliable tools for detection and staging of head and neck cancers. This article describes the role of PET/CT in initial staging of head and neck squamous cell carcinoma, the utility of CT/MR perfusion imaging in qualitative analysis of tumor tissue, and the usefulness of diffusion weighted MR and dynamic contrast-enhanced MR imaging in head and neck oncological imaging.     

Positron emission tomography in gynecological malignancies

Positron emission tomography (PET) is a functional diagnostic imaging technique. F-18 fluoro-2-deoxy-d-glucose (FDG) is a commonly used radiopharmaceutical that is an analog of glucose. PET with FDG is now the standard of care in initial staging, monitoring the response to the therapy and management of various cancers. There is not sufficient data to support the use of PET in the initial diagnosis of cervical cancer; however, FDG-PET has a role in initial staging in the detection of distant metastases in patients with cervical cancer. PET has limited value in lesion localization in early stages of ovarian cancer, but plays a significant role in identifying recurrent tumors in patients with rising tumor markers. In this article, the clinical application of PET in gynecological malignancies is reviewed.     

To PET or not to PET? That is the question. Staging in anal cancer

BackgroundAnal cancer is a rare tumour accounting for ∼2% of all colorectal cancers between 1997 and 2000 in the UK. Staging is still dominated by DRE (digital rectal examination), computed tomography (CT) and magnetic resonance imaging (MRI) imaging. The role of PET as a definitive modality is still emerging and there are relatively few adequate studies in the literature.MethodsWe looked at patients treated radically for anal cancer at Mount Vernon Cancer Centre (UK) between 2009 and 2010. Eighty-eight patients underwent treatment according to data-based coding records of which 46 had positron emission tomography (PET)/CT scans. Notes were unavailable for three patients. We compared staging following conventional modalities (DRE, MRI and CT) and PET/CT scans for these 43 patients.ResultsIn 18 patients, the PET/CT stage differed from MRI. PET/CT altered the stage in 42% of patients but changes in subsequent management were not implemented.ConclusionsOur data show that PET/CT does alter staging in a significant number of cases although it did not lead to change in management under the current guidelines. Furthermore, there is agreement that PET/CT shows greater sensitivity for detection of lymph nodes and our study has demonstrated a distinct trend towards upstaging of anal cancer with PET/CT.     

Positron emission tomography in gynecological malignancies

Positron emission tomography (PET) is a functional diagnostic imaging technique. F-18 fluoro-2-deoxy-d-glucose (FDG) is a commonly used radiopharmaceutical that is an analog of glucose. PET with FDG is now the standard of care in initial staging, monitoring the response to the therapy and management of various cancers. There is not sufficient data to support the use of PET in the initial diagnosis of cervical cancer; however, FDG-PET has a role in initial staging in the detection of distant metastases in patients with cervical cancer. PET has limited value in lesion localization in early stages of ovarian cancer, but plays a significant role in identifying recurrent tumors in patients with rising tumor markers. In this article, the clinical application of PET in gynecological malignancies is reviewed.     

The utility of PET/CT in staging and assessment of treatment response of nasopharyngeal cancer

Introduction: The aim of this study was to evaluate the impact of positron emission tomography/computerised tomography (PET/CT) as an adjunct to conventional imaging (CI) in the management of nasopharyngeal cancer (NPC) both for initial staging and assessment of post‐treatment response. Methods: All NPC cases referred to the Peter MacCallum Centre for Metabolic Imaging between January 2002 and December 2007 were identified. In patients undergoing initial staging, any differences between the pre‐PET/CT management plan based on CI and that following performance of the PET/CT scan were noted. Clinical impact was scored using the Centre's published criteria: 'high' if PET/CT changed the primary treatment modality or intent, ‘medium’ if treatment modality was unchanged but the radiotherapy technique or dose was altered, and ‘low’ if there was no change in treatment modality or intent. Patients undergoing PET/CT following definitive treatment were scored according to whether or not they achieved a complete metabolic response. Results: Forty‐eight patients underwent a staging PET/CT. The clinical impact was high in 8%, medium in 25% and low in 66% of patients. Twenty‐one patients were scanned for post‐treatment response. PET/CT was less frequently equivocal than MRI (3 vs 8/21). A complete metabolic response on PET/CT was associated with a 93% negative predictive value for subsequent recurrence. Conclusion: PET/CT is a valuable staging tool for the detection of occult metastatic disease and defining the extent of neck nodal disease. Post‐treatment, a complete metabolic response on PET/CT has a very high negative predictive value with fewer equivocal results than MRI.     

PET-Bildgebung bei primären Knochentumoren am Beispiel des Osteosarkoms

The value of positron emission tomography (PET) for the diagnosis of osseous tumors remains unclear. Most experience has been gained using F-18-FDG. This radiopharmaceutical is particularly helpful for imaging malignant tumors such as osteosarcoma. For primary staging, conventional x-ray imaging and MRI are the methods of choice. High resolution CT is superior to FDG-PET for diagnosing lung metastases. A clear differentiation for tumor grading and the assessment of prognosis between low and high grade osteosarcoma and non-malignant giant cell tumors or osteomyelitis is difficult due to substantial overlap. Thus, biopsy cannot be replaced. However, FDG-PET may be helpful for guiding biopsies to the area of highest metabolic activity. For therapy control, response to neoadjuvant chemotherapy can be reliably assessed with FDG-PET; this has also been shown in esophageal and colorectal cancer. This is of particular interest as such an assessment cannot be achieved with any other imaging modality. FDG-PET appears to have high sensitivity and specificity for follow-up examinations after the completion of therapy. PET is also not hampered by metallic prosthetic material as is CT and MRI. In conclusion, FDG-PET may be used in patients suffering from osteosarcoma for the assessment of tumor response to neoadjuvant chemotherapy, for the differential diagnosis of postoperative changes and recurrent disease as well as for whole body imaging at follow-up.     

Diagnostic Challenges in Prostate Cancer and 68Ga-PSMA PET Imaging: A Game Changer?

Prostate cancer (PC) is the most frequent solid tumor in men and the third most common cause of cancer mortality among men in developed countries. Current imaging modalities like ultrasound (US), computerized tomography (CT), magnetic resonance imaging (MRI) and choline based positron emission (PET) tracing have disappointing sensitivity for detection of nodal metastasis and small tumor recurrence. This poses a diagnostic challenge in staging of intermediate to high risk PC and restaging of patients with biochemical recurrence (PSA >0.2 ng/ml). Gallium-68 labeled prostate specific membrane antigen (68Ga-PSMA) PET imaging has now emerged with a higher diagnostic yield. 68Ga-PSMA PET/CT or PET/MRI can be expected to offer a one-stop-shop for staging and restaging of PC. PSMA ligands labeled with alpha and beta emitters have also shown promising therapeutic efficacy for nodal, bone and visceral metastasis. Therefore a PSMA based theranostics approach for detection, staging, treatment, and follow-up of PC would appear to be highly valuable to achieve personalized PC treatment.     

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.