Correlation of fine needle aspiration biopsy and fluoride-18 fluorodeoxyglucose positron emission tomography in the assessment of locally recurrent and metastatic head and neck neoplasia

PET Molecular Imaging-Directed Biopsy: A Review

OBJECTIVE

The purpose of this review is to summarize the applications of PET molecular imaging-directed biopsy of a variety of organs in the management of various diseases with a focus on cancers.

CONCLUSION

PET can yield metabolic information at the cellular and molecular levels, and PET-directed biopsy is playing an increasing role in the diagnosis and staging of diseases.

Correlation of fine-needle aspiration with fluorodeoxyglucose positron emission tomography and ultrasonography imaging in head and neck lymph nodes

INTRODUCTION

Fluorodeoxyglucose positron emission tomography (FDG-PET) is a well-established tracer technique, particularly useful for oncologic conditions. However, in the head and neck region, this modality may have limitations due to the complex anatomy and high frequency of normal variants in FDG-PET uptake resulting in diagnostic errors. Hence, FDG-PET results often require additional diagnostic investigations including ultrasonography (US), and guided fine-needle aspirations (FNAs) in order to improve diagnosis and patient care.

MATERIALS AND METHODS

A total of 87 cases of head and neck lymph node FNA were accessioned in the cytopathology laboratory between 2010 and 2013, 75 cases with corresponding standard uptake values (SUVs) were selected to form the current study cohort. Patient demographics, primary tumor site, size of the biopsied lymph node, PET SUV, and US findings, as well as FNA diagnoses and surgical follow-ups were reviewed. SUVs were grouped into 5 ranges: A (2.2-2.9), B (3.0-4.9), C (5.0-6.9), D (7.0-9.9), and E (10.0 +).

RESULTS

The SUV cutoff of 5.0 was seen in the groups C, D, and E, which increased the probability of malignancy in the FNA specimens from 67% to 100%. The average size of the lymph nodes was 18.57 mm (range 6-41 mm); it was 13.4, 14.2, 19.7, 18.4, and 20.2 for groups A, B, C, D, and E, respectively. The lymph node measurements represented similarities in groups A and B (13.4, 14.2), and groups C, D, and E (19.7, 18.4, 20.2). Albeit a few exceptions, an increase in the lymph node size 14.2 to 19.7 (ie, from groups A and B to groups C, D, and E) correlated with SUV and US abnormalities. Abnormal US findings were pronounced (100%) in group E, and ranged between 67% and 73% of the cases in other groups.

CONCLUSIONS

This study documents the usefulness of SUV range in FDG-PET results and not an absolute "cutoff" number for diagnosing suspicious head and neck lymph nodes due to an overlap in the SUVs between malignant and benign lesions. False positive and negative results may occur in hyperplastic and necrotic lymph nodes. An increase in the lymph node size generally compares well with SUVs and US abnormalities; use of US-guided FNAs in these cases can be helpful to achieve definite diagnosis.

Imaging-guided biopsy of (18)F-FDG-avid extrapulmonary lesions: do lesion location and morphologic features on CT affect the positive predictive value for malignancy?

OBJECTIVE

The purpose of our study was to analyze the effect of lesion location and morphologic appearance on CT on the positive predictive value (PPV) for malignancy of all extrapulmonary lesions that were (18)F-FDG avid on PET/CT and that were biopsied under imaging guidance.

MATERIALS AND METHODS

Between January 2004 and December 2010, 227 patients underwent imaging-guided biopsy of 231 PET-positive extrapulmonary lesions with diagnostic pathologic results. The PET PPV for malignancy was retrospectively calculated and stratified according to lesion location and morphologic appearance.

RESULTS

The overall PET PPV for malignancy was 72%. Inflammatory processes accounted for the majority of benign biopsy results. Lesion location significantly affected the PPV (p < 0.001). Bone (96%) and liver (90%) lesions had significantly higher PPVs for malignancy compared with other locations, whereas lymph nodes (60%) had a significantly lower PPV for malignancy. Lesions that were morphologically suspicious and morphologically benign according to CT findings alone were associated with PPVs of 74% and 57%, respectively (p = 0.05). FDG-avid subcentimeter lymph nodes (n = 8) had a PPV for malignancy of 38%.

CONCLUSION

Over half of PET-avid morphologically benign-appearing lesions and one third of PET-avid subcentimeter lymph nodes were found to be malignant at biopsy, suggesting that benign morphologic appearance alone should not preclude further workup of a PET-positive lesion. Biopsies of FDG-avid lesions in liver and bone yielded high rates of true malignancy, whereas biopsies of lymph nodes yielded a lower rate of malignancy compared with other lesion locations.

¹⁸F-FDG-PET imaging in radiotherapy tumor volume delineation in treatment of head and neck cancer

PURPOSE

To determine the impact of (18)F-fluorodeoxyglucose positron emission tomography (PET) in radiotherapy target delineation and patient management for head and neck squamous cell carcinoma (HNSCC) compared to computed tomography (CT) alone.

MATERIALS AND METHODS

Twenty-nine patients with HNSCC were included. CT and PET/CT obtained for treatment planning purposes were reviewed respectively by a neuroradiologist and a nuclear medicine specialist who were blinded to the findings from each other. The attending radiation oncologist together with the neuroradiologist initially defined all gross tumor volume of the primary (GTVp) and the suspicious lymph nodes (GTVn) on CT. Subsequently, the same radiation oncologist and the nuclear medicine specialist defined the GTVp and GTVn on (18)F-FDG-PET/CT. Upon disagreement between CT and (18)F-FDG-PET on the status of a particular lymph node, an ultrasound-guided fine needle aspiration was performed. Volumes based on CT and (18)F-FDG-PET were compared with a paired Student's t-test.

RESULTS

For the primary disease, four patients had previous diagnostic tonsillectomy and therefore, FDG uptake occurred in 25 patients. For these patients, GTVp contoured on (18)F-FDG-PET (GTVp-PET) were smaller than the GTVp contoured on CT (GTVp-CT) in 80% of the cases, leading to a statistically significant volume difference (p=0.001). Of the 60 lymph nodes suspicious on PET, 55 were also detected on CT. No volume change was observed (p=0.08). Ten biopsies were performed for lymph nodes that were discordant between modalities and all were of benign histology. Distant metastases were found in two patients and one had a newly diagnosed lung adenocarcinoma.

CONCLUSIONS

GTVp-CT was significantly larger when compared to GTVp-PET. No such change was observed for the lymph nodes. (18)F-FDG-PET modified treatment management in three patients, including two for which no curative radiotherapy was attempted. Larger multicenter studies are needed to ascertain whether combined (18)F-FDG-PET/CT in target delineation can influence the main clinical outcomes.

Detection of locoregional recurrent head and neck cancer after (chemo)radiotherapy using modern imaging

After radiotherapy with or without chemotherapy differentiation between residual and recurrent head and neck cancer and (chemo)radiation sequelae is often difficult. Currently, most physicians aggressively pursue potential recurrences, leading to a high rate of futile invasive diagnostic, e.g. examinations under general anaesthesia with taking of biopsies, and surgical procedures, e.g. planned neck dissections, and a waste of health care resources. Therefore, diagnostic techniques which reliably select patients who should undergo these procedures are warranted. Conventional imaging techniques are not reliable enough for this purpose. Potential imaging techniques to detect residual and recurrent locoregional disease after chemoradiation are (serial) CT or MRI and FDG-PET, eventually in combination with specific response criteria or scoring systems. Diffusion MRI and PET/CT may further improve these techniques. FDG-PET may help to select patients clinically suspected of recurrent laryngeal carcinoma after radiotherapy for direct laryngoscopy under general anaesthesia. It is not yet clear whether FDG-PET can reliable avoid futile routine evaluation by examination under general anaesthesia in oral and oropharyngeal cancer and planned neck dissection when a residual mass persists in the neck after (chemo)radiation. The most reliable scoring criteria and the optimal time interval between completion of radiation and FDG-PET still has to be assessed.

FDG-PET Evaluation of Response to Treatment

This article discusses evaluating response after and during therapy in various settings and for the types of cancers for which ample evidence demonstrates that PET imaging with flourodeoxyglucose provides a valuable surrogate for response to therapy. It also briefly discusses pitfalls in obtaining an optimal assessment of response and issues that need further attention for this modality to become established as an independent predictor of response to anticancer therapy.

[Evaluation of efficacy and clinical impact of positron emission tomography with 18F fluoro-deoxyglucose (FDG) in patients with suspicion of recurrent laryngeal carcinoma]

AIMS

To evaluate the efficacy and clinical impact of FDG-PET in patients with suspected recurrent laryngeal carcinoma.

MATERIALS AND METHODS

15 patients, with suspicion of recurrent laryngeal carcinoma and ambiguous conventional imaging modalities. In all patients a whole body scan was performed with FDG-PET in fasting patients following i.v. administration of 370-444 MBq FDG. The results were confirmed by histology and clinical evolution (follow-up period > 12 months).

RESULTS

Prevalence of recurrence was 86.6%. FDG-PET was positive in 13 patients, with confirmation in all cases, and 2 were true negative (TN). Overall sensitivity, specificity, PPV, NPV and accuracy were 100%. FDG-PET changed the modality of treatment in 10 patients (clinical impact 63.3%).

CONCLUSIONS

FDG-PET has high clinical impact in patients with a suspicion of recurrent laryngeal carcinoma, and should be incorporated to the diagnostic protocols before making a therapy decision.

Investigation of thyroid, head, and neck cancers with PET

PET with [(18)F]-fluorodeoxyglucose (FDG) has been accepted as a useful imaging modality for the diagnosis of a variety of malignancies. This article discusses the use of FDG-PET in the management of patients with thyroid and head or neck cancers.

F-18-fluoro-deoxy-glucose positron-emission tomography scanning in detection of local recurrence after radiotherapy for laryngeal/ pharyngeal cancer

BACKGROUND

The objective of this investigation was to determine whether F18-fluoro-deoxy-glucose (FDG) positron-emission tomography (PET) could differentiate between local recurrence and late radiation effects after radiotherapy for laryngeal/pharyngeal cancer.

METHODS

In a prospective study of 75 patients (67 larynx, eight oro/hypopharynx), 160 laryngoscopies and 109 FDG PET scans were performed on the head and neck region. The mean follow-up time after the first FDG PET scan was 23 months (minimum 1 year).

RESULTS

Local recurrence was diagnosed in 37 patients: 19 after the first biopsy and 18 after follow-up biopsies. For all of the negative initial FDG scans (27), the biopsies that were taken at the same time were negative and no recurrence was seen for at least 1 year. The first FDG scan was a true positive in 34 of 48 patients. In 12 of the 14 patients with false-positive results, FDG scans were repeated; a decreased FDG uptake was found in 9 of the 12. The sensitivity and specificity of the first scan were respectively 92% and 63%; including subsequent FDG scans, the rates were 97% and 82%, respectively.

CONCLUSIONS

When a local recurrence is suspected after radiotherapy for cancer of the larynx/pharynx, an FDG PET scan should be the first diagnostic step. No biopsy is needed if the scan is negative. If the scan is positive and the biopsy negative, a decreased FDG uptake measured in a follow-up scan indicates that a local recurrence is unlikely.