Use of lymphoscintigraphy with SPECT/CT for sentinel node localization in a case of vaginal melanoma

A 45-year-old woman with vaginal melanoma underwent Tc-99m sulfur colloid (filtered) lymphoscintigraphy with the acquisition of planar and SPECT/CT images for localization of a sentinel node before surgery. The study identified both inguinal and perirectal sentinel nodes, which proved beneficial in mapping potential anatomic spread of disease for staging and therapy planning. These results provide evidence for the use of routine SPECT/CT imaging for pelvic lymphoscintigraphic studies or as an adjunct tool for localizing sentinel nodes in cases that would not be demonstrated with planar imaging alone.     

The yield of SPECT/CT for anatomical lymphatic mapping in patients with breast cancer

Purpose  The recently introduced hybrid single-photon emission computed tomography camera with integrated CT (SPECT/CT) fuses tomographic lymphoscintigrams with anatomical data from CT. The purpose of this study was to explore this sophisticated technique in lymphatic mapping in breast cancer patients. Methods  We studied 134 patients who underwent SPECT/CT immediately after late planar imaging when these images showed an unusual drainage pattern (85 patients), a pattern that was difficult to interpret (27 patients), or nonvisualization (22 patients). Results  Planar imaging suggested 271 sentinel nodes in 112 of the 134 patients (84%). SPECT/CT showed 269 of these same nodes and indicated that two sites of radioactivity were caused by skin contamination. SPECT/CT visualized 19 additional sentinel nodes in 15 patients, of whom 11 had non-visualization on planar images. One or more tumour-positive sentinel nodes were seen in 27 patients, and in 4 of these patients (15%), these were visualized only by SPECT/CT. SPECT/CT had no additional value for the surgical approach in 11 patients with persisting nonvisualization (8%), and was of questionable value in 67 other patients (50%). Based on the SPECT/CT images, a more precise incision was made in 48 patients (36%), an extra incision was made in 6 (4%), and an incision was omitted in 2 (1.5%). Conclusion  SPECT/CT detected additional sentinel nodes and showed the exact anatomical location of sentinel nodes in breast cancer patients with inconclusive planar images. SPECT/CT was able to visualize drainage in patients whose planar images did not reveal a sentinel node. Therefore, SPECT/CT facilitates surgical exploration in difficult cases and may improve staging.     

Evaluation and localization of lymphatic drainage and sentinel lymph nodes in patients with head and neck melanomas by hybrid SPECT/CT lymphoscintigraphic imaging

In patients with head and neck tumors, preoperative lymphoscintigraphy can be used to map lymphatic drainage patterns and identify sentinel lymph nodes. However, it is very difficult to determine the exact locations of head and neck sentinel nodes on preoperative lymphoscintigraphy without the use of anatomic landmarks. Lymph nodes in the head and neck are grouped into 7 regions, or levels, on the basis of anatomic landmarks. In patients undergoing standard lymphoscintigraphy, obtaining lateral marker images that show important anatomic landmarks can help with the localization of sentinel nodes. However, technical problems often render marker images of little or no use. Hybrid SPECT/CT lymphoscintigraphic imaging facilitates the localization of sentinel nodes by reliably showing the relationships between sentinel nodes and important anatomic structures. After reading this article, the reader should understand the lymph node level classification system for head and neck melanomas, be able to describe the technique used for the imaging of sentinel nodes in the head and neck region, and be able to demonstrate how SPECT/CT lymphoscintigraphic imaging can enable precise sentinel node localization and thus help to ensure minimal dissection.     

The additional value of SPECT/CT in lymphatic mapping in breast cancer and melanoma.

The recently introduced SPECT/CT integrates the physiologic data of SPECT with the anatomic data of CT into a single image. The purpose of this pilot study was to explore the additional value of SPECT/CT in breast cancer patients and melanoma patients with inconclusive planar image findings. METHODS: Thirty-one patients had planar lymphoscintigrams showing unexpected lymphatic drainage, 6 had lymphoscintigrams that were difficult to interpret, and 3 showed no drainage on planar imaging. SPECT/CT was performed immediately after delayed planar imaging. RESULTS: In 4 patients, SPECT/CT showed 6 additional sentinel nodes, of which 2 were tumor-positive and led to upstaging and tailored management in 5% of patients. SPECT/CT depicted sentinel nodes in 3 patients whose delayed planar imaging had shown no drainage. CONCLUSION: SPECT/CT was of additional value in finding the exact anatomic location of sentinel nodes in patients with inconclusive planar image findings. SPECT/CT also detected sentinel nodes in addition to those found on planar images, and SPECT/CT detected sentinel nodes in patients whose planar images had shown none.     

Three-dimensional localization of sentinel lymph nodes using combined emission and transmission SPECT data

PURPOSE: With conventional planar imaging, preoperative anatomic localization of a sentinel lymph node is possible in only two dimensions. To improve spatial localization of sentinel lymph nodes, a dual-head camera equipped with a transmission source was used to create combined transmission-emission SPECT images in a patient with a malignant melanoma of the left forearm. METHODS: Lymph node scintigraphy was performed after injection of Tc-99m-labeled nanocolloid around the tumor site 1 day before operation. SPECT was performed using a gamma camera equipped with a transmission collimator system originally designed to correct attenuation. Transmission and emission images were created simultaneously, matched, and displayed in three dimensions. RESULTS: In the combined emission-transmission images, the sentinel lymph node was clearly located in the left axilla. The lymph nodes could be identified during operation at the same location as that detected by SPECT. Based on preoperative information, the sentinel lymph node was identified rapidly and the extent and duration of the operation were minimized. CONCLUSIONS: This method provides better anatomic information, especially in deep structures such as the axilla or pelvis. With accurate three-dimensional preoperative information, intraoperative access is quicker and less invasive for the patient.     

Evaluation of the sentinel lymph node combining SPECT/CT with the planar image and its importance for the surgical act

The sentinel node biopsy procedure is based on the hypothesis of the existence of an orderly and predictable pattern of lymphatic drainage to a regional lymph node basin. This results in the consideration of all lymph nodes with direct drainage from the primary tumor as sentinel nodes. The sentinel node is not necessarily the hottest or the most nearby node, although this is often the case. Lymphoscintigraphy has been an essential component for preoperative sentinel node identification. With the new generation of multimodality gamma cameras, SPECT/CT has been incorporated into the sentinel node procedure. The resulting SPECT/CT fused images depict sentinel nodes in an anatomical landscape providing a helpful roadmap for surgeons. Therefore, it is necessary to define the role of SPECT/CT in relation to the classical planar lymphoscintigraphy for the identification of sentinel nodes. To understand the combined use of lymphoscintigraphy and SPECT/CT, the criteria for sentinel node identification on preoperative images must be specified. The authors, based on their experience in this field, present tentative criteria to identify lymph nodes as sentinel nodes both in planar and SPECT/CT images and classify them into different categories. The use of these scintigraphic categories to characterize radioactive lymph nodes is also helpful for surgical decision making.     

The hidden sentinel node and SPECT/CT in breast cancer patients

Purpose  In a minority of breast cancer patients, lymphoscintigraphy shows no lymphatic drainage and ‘hidden’ sentinel nodes may remain undiscovered. The purpose of this study was to explore the additional value of the recently introduced hybrid SPECT/CT in breast cancer patients with axillary non-visualisation on planar images. The role of blue dye and careful palpation of the axilla was evaluated in patients in whom axillary sentinel nodes remained hidden after SPECT/CT. Methods  Fifteen breast cancer patients with non-visualisation on planar lymphoscintigraphy and 13 women with only extra-axillary sentinel nodes underwent SPECT/CT following late planar imaging without re-injection of the radiopharmaceutical. Results  SPECT/CT visualised lymphatic drainage in eight of the 15 patients (53%) with non-visualisation on planar imaging, depicted nine of the 14 harvested sentinel nodes (64%) and three of five tumour-positive sentinel nodes. In two of the 13 patients (15%) with only extra-axillary sentinel nodes on their planar lymphoscintigram, SPECT/CT showed an axillary sentinel node that appeared to be uninvolved. Careful exploration of the axilla with the combined use of blue dye, a gamma probe and intra-operative palpation revealed an axillary sentinel node in the remaining 18 patients. SPECT/CT showed the exact anatomical location of all visualised sentinel nodes. Conclusion  SPECT/CT discovered ‘hidden’ sentinel nodes in the majority of patients with non-visualisation, but was less valuable in patients with only extra-axillary lymphatic drainage on the planar images. Exploration of the axilla in patients with persistent non-visualisation improved the identification of axillary (involved) sentinel nodes.     

Fusion of SPECT and multidetector CT images for accurate localization of pelvic sentinel lymph nodes in prostate cancer patients

OBJECTIVE: The present study was performed to investigate the feasibility of fusion of images obtained by SPECT and multidetector CT (MDCT) for the accurate localization of sentinel lymph nodes in prostate cancer patients. METHODS: To facilitate the fusion of both SPECT and CT images, a pelvic MDCT scan was performed with 3 markers of small plastic bullets attached to the skin over the bilateral iliac crests and the ventral midline at the same height. SPECT was performed after the same locations were marked with needle caps containing (99m)Tc-pertechnetate. The images were superimposed by use of free software (MRIcro). The results of hot lymph node detection with fusion images were compared with those of surgery. RESULTS: The images could be successfully superimposed for all 11 patients examined. Surgeons accurately confirmed 27 (87.1%) of 31 regional lymph nodes on fusion images. CONCLUSION: Fusion of SPECT and MDCT images is useful for the precise localization of sentinel lymph nodes in prostate cancer patients.     

SPECT/CT in the Treatment of Differentiated Thyroid Cancer

Single-photon emission computed tomography with integrated computed tomography (SPECT/CT) systems has been applied in a wide range of clinical circumstances, and differentiated thyroid cancer (DTC) is one of the most important indications of SPECT/CT imaging. In the treatment of DTC, SPECT/CT images have been reported to have many advantages over conventional planar whole-body scintigraphy based on its precise localization and characterization of abnormal foci of radioactive iodine (RAI) accumulation, influencing the staging, risk stratification, and clinical management as well as reader confidence. On the other hand, SPECT/CT has limitations including additional radiation exposure from the CT component, additional imaging time, and cost-related issues. Each SPECT/CT image acquired at different time points throughout the management of DTC may have a different clinical meaning and significance. This review article addresses the clinical usefulness of RAI SPECT/CT images acquired during the pre-ablation period, post-therapy period, and long-term follow-up period, respectively.     

Single-photon emission computed tomography/computed tomography in lung cancer and malignant lymphoma

In nuclear oncology, despite the fast-growing diffusion of (18)F-fluorodeoxyglucose positron emission tomography (FDG-PET), single-photon emission computed tomography (SPECT) studies can still play an useful clinical role in several applications. The main limitation of SPECT imaging with tumor-seeking agents is the lack of the structural delineation of the pathologic processes they detect; this drawback sometimes renders SPECT interpretation difficult and can diminish its diagnostic accuracy. Fusion with morphological studies can overcome this limitation by giving an anatomical map to scintigraphic data. In the past, software-based fusion of independently performed SPECT and CT images proved to be time-consuming and impractical for routine use. The recent development of dual-modality integrated imaging systems that provide functional (SPECT) and anatomical (CT) images in the same scanning session, with the acquired images coregistered by means of the hardware, has opened a new era in this field. The first reports indicate that SPECT/CT is very useful in cancer imaging because it is able to provide further information of clinical value in several cases. In SPECT, studies of lung cancer and malignant lymphomas using different radiopharmaceutical, hybrid images are of value in providing the correct localization of tumor sites, with a precise detection of the involved organs, and the definition of their functional status, and in allowing the exclusion of disease in sites of physiologic tracer uptake. Therefore, in lung cancer and lymphomas, hybrid SPECT/CT can play a role in the diagnosis of the primary tumor, in the staging of the disease, in the follow-up, in the monitoring of therapy, in the detection of recurrence, and in dosimetric estimations for target radionuclide therapy.     

Single-photon emission computed tomography/computed tomography in brain tumors

Anatomic imaging procedures (computed tomography [CT] and magnetic resonance imaging [MRI]) have become essential tools for brain tumor assessment. Functional images (positron emission tomography [PET] and single-photon emission computed tomography [SPECT]) can provide additional information useful during the diagnostic workup to determine the degree of malignancy and as a substitute or guide for biopsy. After surgery and/or radiotherapy, nuclear medicine examinations are essential to assess persistence of tumor, to differentiate recurrence from radiation necrosis and gliosis, and to monitor the disease. The combination of functional images with anatomic ones is of the utmost importance for a full evaluation of these patients, which can be obtained by means of imaging fusion. Despite the fast-growing diffusion of PET, in most cases of brain tumors, SPECT studies are adequate and provide results that parallel those obtained with PET. The main limitation of SPECT imaging with brain tumor-seeking radiopharmaceuticals is the lack of precise anatomic details; this drawback is overcome by the fusion with morphological studies that provide an anatomic map to scintigraphic data. In the past, software-based fusion of independently performed SPECT and CT or MRI demonstrated usefulness for brain tumor assessment, but this process is often time consuming and not practical for everyday nuclear medicine studies. The recent development of dual-modality integrated imaging systems, which allow the acquisition of SPECT and CT images in the same scanning session, and their co-registration by means of the hardware, has facilitated this process. In SPECT studies of brain tumors with various radiopharmaceuticals, fused images are helpful in providing the precise localization of neoplastic lesions, and in excluding the disease in sites of physiologic tracer uptake. This information is useful for optimizing diagnosis, therapy monitoring, and radiotherapy treatment planning, with a positive impact on patient management.     

Mediastinal lymph node involvement in non-small cell lung cancer: evaluation with 99mTc-tetrofosmin SPECT and comparison with CT.

In patients with non-small cell lung cancer (NSCLC), surgical resection offers the best chance of cure. The preoperative assessment of mediastinal lymph node involvement is crucial to selecting those patients for whom surgery is indicated. METHODS: To evaluate the possible clinical role of (99m)Tc-tetrofosmin scintigraphy in the presurgical detection of mediastinal node metastases from NSCLC, we performed a prospective comparative study with CT on 83 patients (48 men, 35 women; age range, 38-81 y) with primary NSCLC (36 adenocarcinomas, 39 epidermoid squamous cell carcinomas, and 8 large cell anaplastic carcinomas). They underwent chest SPECT 20 min after (99m)Tc-tetrofosmin injection (740 MBq intravenously). The metastatic involvement of mediastinal nodes was assessed by histologic examination after mediastinoscopy or thoracotomy. Both chest CT and (99m)Tc-tetrofosmin scintigraphy were performed within 2 wk before the surgical staging. RESULTS: Metastatic mediastinal lymph nodes were found in 35 patients. (99m)Tc-Tetrofosmin imaging in assessing the mediastinal involvement yielded a sensitivity of 85.7%, a specificity of 89.6%, and an accuracy of 88.0%; CT results were 68.6%, 75.0%, and 72.3%, respectively. SPECT accuracy was significantly higher than CT accuracy (P < 0.05). However, precise anatomic localization of (99m)Tc-tetrofosmin uptake in the mediastinum was not always present on SPECT images. (99m)Tc-Tetrofosmin SPECT precisely detected the presence or absence of lymph node metastases in 33 of the 36 patients with positive CT findings (enlarged mediastinal nodes with a short axis > or =1 cm), with an accuracy (91.7%) significantly higher (P < 0.05) than that of CT (66.7%). CONCLUSION: (99m)Tc-Tetrofosmin SPECT is a useful presurgical noninvasive method to assess mediastinal lymph node involvement in NSCLC. In particular, it could play a clinical role in reducing the number of invasive staging surgical procedures in selected patients, especially in those with enlarged lymph nodes at CT. Fusing SPECT with CT images could further improve the interpretation of the scintigraphic data.     

SPECT/CT.

In view of the commercial success of integrated PET/CT scanners, there is an increasing interest in comparable SPECT/CT systems. SPECT in combination with CT enables a direct correlation of anatomic information and functional information, resulting in better localization and definition of scintigraphic findings. Besides anatomic referencing, the added value of CT coregistration is based on the attenuation correction capabilities of CT. The number of clinical studies is limited, but pilot studies have indicated a higher specificity and a significant reduction in indeterminate findings. The superiority of SPECT/CT over planar imaging or SPECT has been demonstrated in bone scintigraphy, somatostatin receptor scintigraphy, parathyroid scintigraphy, and adrenal gland scintigraphy. Also, rates of detection of sentinel nodes by biopsy can be increased with SPECT/CT. This review highlights recent technical developments in integrated SPECT/CT systems and summarizes the current literature on potential clinical uses and future directions for SPECT/CT in cardiac, neurologic, and oncologic applications.     

Impact of <Superscript>131</Superscript>I-SPECT/CT images obtained with an integrated system in the follow-up of patients with thyroid carcinoma

Purpose The purpose of the study was to determine the diagnostic impact of ¹³¹I-SPECT/CT imaging compared with conventional scintigraphic evaluation in the follow-up of patients with thyroid carcinoma.Methods Seventy-one patients with thyroid carcinoma underwent concurrent ¹³¹I-SPECT/CT, using an integrated imaging system, at various stages of their disease in order to evaluate foci of uptake detected on planar whole-body images.Results SPECT/CT imaging had an incremental diagnostic value in 57% (41/71) of patients. Uptake in the neck was evaluated in 61 patients, and SPECT/CT imaging in this region had an incremental diagnostic value in 27% of the whole patient population (19/71). Low-resolution integrated CT images allowed for the precise characterization of equivocal neck lesions on planar imaging in 14/17 patients and changed the assessment of the lesion location in five patients as compared with planar studies. Thirty-six patients underwent SPECT/CT for evaluation of foci of uptake distant from the neck. SPECT/CT imaging improved characterization of equivocal foci of uptake as definitely benign in 13% (9/71) of patients. Precise localization of malignant lesions to the skeleton was possible in 17% (12/71) and to the lungs versus the mediastinum in 6% (5/71) of patients.Conclusion Integrated ¹³¹I-SPECT/CT was found to have an additional value over planar imaging in patients with thyroid cancer for correct characterization of equivocal tracer uptake seen on planar imaging as well as for precise localization of malignant lesions in the neck, chest, and skeleton. SPECT/CT optimized the localization of ¹³¹I uptake to lymph node metastases versus remnant thyroid tissue, to lung versus mediastinal metastases, and to the skeleton. It also had a further clinical impact on patient management by influencing referral for ¹³¹I treatment, tailoring of the administered radioiodine dose, and/or the addition of surgery or external radiation therapy when indicated.     

Lymphoscintigraphy and SPECT/CT in multicentric and multifocal breast cancer: does each tumour have a separate drainage pattern?

Purpose

To investigate whether lymphoscintigraphy and SPECT/CT after intralesional injection of radiopharmaceutical into each tumour separately in patients with multiple malignancies in one breast yields additional sentinel nodes compared to intralesional injection of the largest tumour only.

Methods

Patients were included prospectively at four centres in The Netherlands. Lymphatic flow was studied using planar lymphoscintigraphy and SPECT/CT until 4?h after administration of ^99mTc-nanocolloid in the largest tumour. Subsequently, the smaller tumour(s) was injected intratumorally followed by the same imaging sequence. Sentinel nodes were intraoperatively localized using a gamma ray detection probe and vital blue dye.

Results

Included in the study were 50 patients. Additional lymphatic drainage was depicted after the second and/or third injection in 32 patients (64?%). Comparison of planar images and SPECT/CT images after consecutive injections enabled visualization of the number and location of additional sentinel nodes (32 axillary, 11 internal mammary chain, 2 intramammary, and 1 interpectoral. A sentinel node contained metastases in 17 patients (34?%). In five patients with a tumour-positive node in the axilla that was visualized after the first injection, an additional involved axillary node was found after the second injection. In two patients, isolated tumour cells were found in sentinel nodes that were only visualized after the second injection, whilst the sentinel nodes identified after the first injection were tumour-negative.

Conclusion

Lymphoscintigraphy and SPECT/CT after consecutive intratumoral injections of tracer enable lymphatic mapping of each tumour separately in patients with multiple malignancies within one breast. The high incidence of additional sentinel nodes draining from tumours other than the largest one suggests that separate tumour-related tracer injections may be a more accurate approach to mapping and sampling of sentinel nodes in patients with multicentric or multifocal breast cancer.     

The role of single-photon emission computed tomography/computed tomography for precise localization of metastases in patients with differentiated thyroid cancer

PurposeIt is very important in the management of patients with differentiated thyroid cancer (DTC) to precisely localize the foci of I-131 uptake, but it is difficult because of a lack of anatomic landmarks. The purpose of this study was to investigate the added value of I-131 single-photon emission computed tomography (SPECT)/computed tomography (CT) fusion imaging using a hybrid system in patients with DTC.MethodsNinety-four patients with DTC underwent I-131 SPECT/CT using a hybrid tomography consisting of a dual-head variable-angle gamma camera and a low-dose X-ray tube. Results were compared with I-131 whole-body scan (WBS). SPECT/CT was performed 5–7 days after administration of a therapeutic dose of I-131. Fusion images were constructed by combining the digital CT and SPECT images on a computer workstation.ResultsCompared with I-131 WBS, SPECT/CT imaging had improved the precise localization in 21% (20/94) of patients. In addition, SPECT/CT provided additional clinical data in 12 of the patients examined (12/94) and also caused physicians to reconsider the ¹³¹I therapeutic approach in 22 patients.ConclusionThe results of the current study indicate that the addition of I-131 SPECT/CT to WBS can improve the localization of metastases in patients with DTC. It may also detect metastases missed by WBS and adjust the therapy plan.     

A preliminary study on sentinel lymph node biopsy: feasibility and predictive ability in oral cavity cancer

The main factor that affects the prognosis of patients with head and neck cancer (HNC) is regional lymph node metastases. For this reason, the accurate evaluation of neck metastases is required for neck management. This study investigates the sentinel lymph node identification and the accuracy of the histopathology of the sentinel lymph node in patients with HNC. Eleven patients with histologically proven oral squamous cell carcinoma accessible to radiocolloid injection were enrolled in this study. Using both lymphoscintigraphy and a handheld gamma probe, the sentinel lymph node could be identified in all 11 patients. Subsequently, the sentinel lymph nodes and the neck dissection specimen were examined for lymph node involvement due to tumor. The histopathology of sentinel lymph nodes was consistent with the pathological N classification in all 11 patients. Furthermore, the histopathology of sentinel lymph nodes was superior to physical examination, computed tomography (CT), magnetic resonance imaging (MRI) and positron emission tomography (PET) scan. The results of this study indicate that sentinel lymph node identification is technically feasible and predicts cervical metastases in patients with oral cavity cancer. This may be a useful diagnostic technique for identifying lymph node disease in staging lymph node dissection.     

^99mTc—平阳霉素显像在肺癌分期中的临床应用研究

肺癌的分期对其获得适当的治疗尤为重要。对３０例原发性肺癌行９９ｍＴｃ－平阳霉素（ＰＹＭ）显像分期研究，单光子发射计算机断层（ＳＰＥＣＴ）对纵隔及肺门淋巴结浸润的发现能力与Ｘ－ＣＴ一致（肺门９／９，纵隔１３／１３），肝转移显示３／４。对恶性胸水除可显示积液外，尚可较好地显示原发病灶（平面６／７，ＳＰＥＣＴ７／７），提示该显像可用于肺癌分期检查     

Imaging in primary penile cancer: current status and future directions

Penile cancer is a rare neoplasm in the developed world. Clinical assessment often results in inaccurate staging and radiological techniques have a key role in staging and postoperative assessment. Magnetic resonance imaging (MRI) depicts penile anatomy in detail and is the most accurate technique for local staging and postoperative follow-up. MRI and ultrasound (US), although helpful for assessment of lymph nodes, are not reliable enough for accurate nodal staging. US-guided fine needle aspiration cytology (FNAC), however, remains a valuable tool to confirm metastases in suspicious inguinal nodes. Lymphoscintigraphy with dynamic sentinel node biopsy (DSNB) is a promising technique used to predict occult lymph node metastases. Novel imaging techniques such as positron emission tomography/computed tomography (PET-CT) and nanoparticle enhanced MRI have high sensitivity and specificity for lymph node metastases but their availability is limited and clinical utility is not fully established. The radiologist needs to be familiar with the normal penile anatomy, imaging appearances of pre- and post-treatment penile cancer, and the advantages and limitations of the available imaging techniques. This review highlights the above points and presents a systematic approach to make the best use of imaging in the management of patients with penile cancer.     

Fusion of Freehand SPECT and Ultrasound to Perform Ultrasound-Guided Fine-Needle Aspiration Cytology of Sentinel Nodes in Head and Neck Cancer

BACKGROUND AND PURPOSE:Criteria for ultrasound-guided fine-needle aspiration cytology (USgFNAC) for the detection of occult lymph node metastasis in patients with clinically negative head and neck cancer are based on the morphology of cervical lymph nodes. To improve the selection of lymph nodes for USgFNAC, we examined the feasibility of fused freehand single-photon emission tomography ultrasound-guided fine-needle cytology (freehand SPECT-USgFNAC) of sentinel nodes in patients with early stage oral and head and neck skin cancer.MATERIALS AND METHODS:Six patients with early-stage head and neck cancer (4 oral and 2 head and neck skin cancers) and a clinically negative neck who were scheduled for transoral or local excision and a sentinel node procedure underwent USgFNAC and freehand SPECT-USgFNAC preoperatively.RESULTS:All freehand SPECT sonographic examinations were technically successful in terms of identifying sentinel nodes. All aspirates of sentinel nodes obtained by freehand SPECT-USgFNAC contained substantial radioactivity, confirming puncture of the sentinel nodes. USgFNAC evaluated 13 lymph nodes; freehand SPECT-USgFNAC, 19 nodes; and sentinel node biopsy, 13 nodes. Three sentinel nodes were histopathologically positive and were selected for aspiration cytology by freehand SPECT-USgFNAC, but not by conventional ultrasound. The cytologic examination findings of the aspirations were negative or inconclusive.CONCLUSIONS:Freehand SPECT ultrasound can identify sentinel nodes and could potentially improve USgFNAC in patients with head and neck cancer by better selection of lymph nodes at highest risk of having metastases (sentinel nodes), but its sensitivity is limited by sampling error and insufficient aspirated material for cytology.

Head and neck cancer has a high propensity for metastasizing through the lymphatics to regional lymph nodes rather than spreading hematogenously. It is universally accepted that the neck has to be treated by either surgery with or without adjuvant radiation or chemoradiation or by primary radiation or chemoradiation when lymph node metastases are present.In patients with clinically node-negative (cN0) tumors, occult metastases or micrometastases are still present in approximately 30% of cases. Clinical staging by palpation is typically followed by imaging with CT, MR imaging, positron-emission tomography, ultrasound (US), and/or ultrasound-guided fine-needle aspiration cytology (USgFNAC).^1,2 USgFNAC is the most reliable of these diagnostic techniques, with a sensitivity of 48%–73% and a specificity approaching 100%.²In an attempt to select the lymph nodes most likely to contain metastases, the sentinel node (SN) concept has been introduced. Sentinel node biopsy (SNB) is a diagnostic staging procedure that is applied in a variety of tumor types, including head and neck skin cancers and oral squamous cell carcinoma (OSCC). The procedure aims to identify the first draining lymph nodes, the SNs that are most likely to have metastases. The histopathologic status of the SN should reflect that of the rest of the nodal basin, and additional treatment of the nodal basin (eg, lymph node dissection) should only be performed in case of metastatic involvement of the SN.³SNB is a reliable diagnostic procedure for staging of the cN0 neck and identifying patients with occult nodal metastatic disease. A recent meta-analysis on SNB in early OSCC showed a pooled sensitivity of 92% and a negative predictive value of 88%–100%.⁴ More recently, a retrospective study of 90 previously untreated patients with early OSCC with a cN0 neck who underwent SNB (only neck dissection after positive findings on SNB) was performed: A lymphoscintigraphic identification rate of 98%, a surgical detection rate of 99%, and an upstaging rate of 30% were found.⁵ SNB has been extensively used in skin cancer, particularly melanoma.⁶Although less invasive compared with elective neck dissection, SNB is still a surgical procedure. Moreover, SNB is more complex and costly than USgFNAC. Therefore, in most centers in which SNB is used, patients are selected for SNB after negative findings of USgFNAC. USgFNAC may thus avoid unnecessary SNB but would also decrease the risk of false-negative SNB when gross metastatic involvement of the node prohibits tracer uptake. If the sensitivity of USgFNAC can be improved, the better yield of this procedure as a first-line technique may reduce the number of SNBs without jeopardizing oncologic outcome. Additionally, SNB may result in fibrosis, making subsequent neck dissection more difficult. Finally, patients can be scheduled immediately for neck dissection and do not have to wait for the results of the time-consuming and labor-intensive SN procedure.Criteria for USgFNAC in patients with cN0 OSCC are based on the morphology of the cervical lymph nodes. Lymph nodes with a minimal axial diameter of >4 mm in level II of the neck and 3 mm in other levels of the neck are selected for USgFNAC to obtain a high sensitivity.⁷ Inaccurate results of USgFNAC are attributed to an absence of enlarged lymph nodes, aspiration of the wrong lymph node, failure of cytologic analysis due to insufficient material for cytopathologic diagnosis, or the presence of micrometastases in parts of the lymph nodes not aspirated (sampling error). Whereas the conventional selection is based on standard drainage patterns and lymph node size and morphology, lymphatic mapping identifying the SN may improve selection of the lymph nodes with the highest risk of having metastases to be aspirated.Freehand single-photon emission tomography is an innovative technique aiming to guide the physician to the exact localization of the radioactive area of interest (eg, the SN). Freehand SPECT is a 3D tomographic technique based on the imaging concepts of SPECT, but with the major difference being that it is based on data acquisition by hand-held detectors instead of gantry-based gamma cameras. The technology is designed to use a conventional gamma probe or hand-held gamma camera for the detection of radiation and positioning systems to determine the position of the detector relative to the patient. On the basis of the integration of the acquired set of detector readouts and their position and orientation, the system is capable of generating 3D nuclear images similar to a SPECT image, thus providing visualization of the SN at any time.^8,9 Freehand SPECT can be integrated with video or other imaging modalities.¹⁰ Recently, the fusion of these 3D nuclear images with US, making SN visualization on US possible, was introduced.^11,12 In this setup, functional (fully 3D freehand SPECT) and anatomic (2D ultrasound) information are combined in real-time.We performed a pilot study to examine the feasibility of freehand SPECT-USgFNAC of SNs in patients with early OSCC and head and neck skin cancer.