The detection of unknown primary tumors in patients with cervical metastases by dual-head positron emission tomography

A dilemma may occur in relation to patients with cervical metastases appearing as the first sign of malignancy in the head and neck region. In these patients, the location of the involved lymph nodes may indicate the location of the primary tumor. However, in two or three per cent of the patients, the primary tumor cannot be identified in the diagnostic workup. The aim of the present study was to investigate the possibility of identification of primary tumors in patients with cervical metastases of unknown origin, by the use of 2-(fluorine-18)fluoro-deoxy-D-glucose (FDG) dual-head positron emission tomography (PET). Ten consecutive patients with a cervical metastases of unknown origin were studied with FDG, using a dual-head PET camera. After the injection of 185 MBq (5 mCi) of FDG, images were performed of the head, neck and chest. In addition, endoscopy and biopsies were carried out with knowledge of the PET study. In patients in whom a primary tumor could not be identified, a follow-up of at least 6 months was used as a control. In five out of 10 patients a primary tumor was identified by FDG-PET. In one patient multiple sites of uptake were seen, and this was found to be consistent with non-Hodgkin lymphoma. In five patients, additional sites of increased uptake were found, these being consistent with unknown metastatic disease. Finally, in six patients, the initial treatment plan was changed due to the PET result in five of them. In one patient, the primary tumor was resected revealing a lesion with a diameter of 6 mm. The detection of FDG in patients with cervical metastases of unknown origin by the use of a dual-head PET camera is a valuable diagnostic tool in the identification of primary lesions.     

Combined 18F-fluorodeoxyglucose-positron emission tomography and computed tomography as a primary screening method for detecting second primary cancers and distant metastases in patients with head and neck cancer.

BACKGROUND: The aim of this study was to evaluate the ability of (18)F-fluorodeoxyglucose-positron emission tomography/computed tomography (FDG-PET/CT) to detect second primary cancers and distant metastases in patients with head and neck cancer (HNC). PATIENTS AND METHODS: Patients with previous untreated HNC, between 2004 and 2005, underwent head and neck CT and whole-body FDG-PET/CT, before and at fixed intervals after therapy, for staging and detection of second primary cancers and distant metastases. Patients with malignant or equivocal findings on FDG-PET/CT underwent further imaging, endoscopy and/or biopsy. RESULTS: Of the 349 eligible patients (267 men and 82 women), 14 (4.0%) had second primary cancers and 26 (7.4%) had distant metastases at initial staging or during mean follow-up of 15 months after treatment. FDG-PET/CT correctly identified second cancers or distant metastases in 39 of these 40 patients; there was one false negative and 23 false positive FDG-PET/CT results. Therefore, FDG-PET/CT had a sensitivity of 97.5%, a specificity of 92.6%, a positive predictive value of 62.9% and a negative predictive value of 99.7% in detecting second primary cancers and distant metastases. CONCLUSION: Combined FDG-PET/CT is useful as a primary method for detecting second cancers and distant metastases in patients with HNC.     

18F-fluorodeoxyglucose positron emission tomography-computed tomography as a diagnostic tool in patients with cervical nodal metastases of unknown primary site: A meta-analysis

BackgroundWe performed a meta-analysis to evaluate the value of ¹⁸F-fluorodeoxyglucose positron emission tomography-computed tomography (¹⁸FDG PET-CT) for the detection of primary sites in patients with cervical nodal metastases of unknown origin.MethodsStudies were systematically searched for relevant PET-CT original articles in the MEDLINE and EMBASE databases. We calculated the primary tumor detection rate, sensitivity, specificity, and likelihood ratios for ¹⁸FDG PET-CT. We also constructed the hierarchic summary receiver operating characteristic curve for ¹⁸FDG PET-CT.ResultsThis present study analyzed a total of 7 selected studies (246 patients). The primary tumor detection rate, sensitivity and specificity of PET-CT were 0.44 (95% confidence interval [CI] = 0.31–0.58), 0.97 (95% CI = 0.63–0.99), and 0.68 (95% CI = 0.49–0.83). Area under the curve was 0.83 (95% CI = 0.80–0.86).Conclusions¹⁸FDG PET-CT has high sensitivity and low specificity for the detection of primary sites in patients with cervical nodal metastases of unknown origin.     

18F-FDG whole body positron emission tomography (PET) in patients with unknown primary tumours (UPT)

The management of patients with unknown primary tumours (UPT) often includes a large number of radiographical studies and invasive procedures, but the occult primary tumour is detected in less than 25%. In this prospective study we explored whether non-invasive whole body PET scans using FDG (18-F-fluorodeoxyglucose) are of clinical value in detection of UPT. Whole-body FDG-PET scans were performed in 20 patients following standard staging procedures according to histology. PET results were verified either histologically or by the clinical course of the disease. 11 patients had neck metastases (5 squamous cell, 5 adenocarcinomas and 1 poorly differentiated carcinoma). The remaining patients had metastases located in bone (3), bone marrow (1), brain (1), pericardium (1), skin (1), pleura (1) and chest wall (1). All metastatic lesions were visible with PET. In 13 patients PET suggested the site for the primary tumour and this was verified in 9 (45%), either histologically or by the clinical course of disease. 8 of these had primary lung cancer and 1 had carcinoma at the basis of the tongue. In most patients PET had no treatment related implications. 3 patients with non-small cell lung cancer (NSCLC) received chemotherapy prompted by the PET result. The rest received either radical radiotherapy to the head and neck region (7), palliative radiotherapy to the metastatic lesion (8), chemotherapy based on signet ring cell carcinoma in bone marrow (1) or no therapy (1). These results indicates that PET is useful in UPT preceding expensive and invasive diagnostic procedures and can result in a faster diagnosis in approximately one third of the patients who then avoid unnecessary extensive procedures. Furthermore, a larger proportion of patients will receive treatment aimed at the correct diagnosis. A prospective cost-effectiveness analysis of PET in this setting is warranted     

The role of fluorodeoxyglucose positron emission tomography in cervical lymph node metastases from an unknown primary tumor

BACKGROUND: The authors performed a comprehensive review of the efficacy of fluorodeoxyglucose positron emission tomography (FDG-PET) in the detection of primary tumors in patients with cervical metastases from unknown primary tumors. METHODS: Sixteen studies (involving a total of 302 patients) published between 1994 and 2003 were reviewed. These studies evaluated the role of FDG-PET in the detection of unknown primary tumors after conventional workup. In all studies, conventional workup included either panendoscopy or computed tomographic/magnetic resonance imaging, and in 10 of 16 studies, both of these diagnostic techniques were performed before diagnosis. RESULTS: The overall sensitivity, specificity, and accuracy rates of FDG-PET in detecting unknown primary tumors were 88.3%, 74.9%, and 78.8%, respectively. Furthermore, FDG-PET detected 24.5% of tumors that were not apparent after conventional workup. FDG-PET imaging also led to the detection of previously unrecognized metastases in 27.1% of patients (regional, 15.9%; distant, 11.2%). FDG-PET had notably low specificity and a high false-positive rate (39.3%) in the tonsils. In contrast, the false-positive rates for FDG-PET of the base of tongue and hypopharynx were only 21.4% and 8.3%, respectively. FDG-PET exhibited decreased sensitivity to tumors in the base of tongue (81.5%). The sensitivity of this technique at other sites was 90.5%. CONCLUSIONS: FDG-PET detected primary tumors that went undetected by other modalities in approximately 25% of cases and was sensitive in the detection of previously unrecognized regional or distant metastases in 27% of cases. FDG-PET had low specificity for tonsillar tumors and low sensitivity for base-of-tongue malignancies.     

18F-fluorodeoxyglucose-positron emission tomography and bone scintigraphy for detecting bone metastases in patients with malignancies of the upper aerodigestive tract

The role of 18F-fluorodeoxyglucose (FDG)-positron emission tomography (PET) in identifying bone metastases in patients with head and neck cancer is not clear. We compared the ability of FDG-PET and bone scintigraphy (BS) to detect bone metastases in patients with upper aerodigestive tract (UADT) malignancies. Patients with histologically confirmed malignancies in the UADT underwent both FDG-PET and BS at initial staging or follow-up. The two methods were compared in patients and in seven skeletal regions. Maximum standard uptake value (SUVmax) on PET was calculated in each lesion and compared between true- and false-positive lesions. This study included 564 eligible patients, of whom 17 had bone metastases. The spine was the most frequently involved site, followed by the lungs and liver. Both FDG-PET and BS had high specificity, accuracy, and negative predictive values for detecting bone metastases (>95% each), and the two methods did not differ in sensitivity, specificity, and predictive values (P>0.05). Both FDG-PET (n=15) and BS (n=14) yielded a significant number of false-positive results, which could be corrected by further work-ups and follow-up imaging. Compared with true-positive lesions, the false-positive lesions on FDG-PET were usually single (86.7% vs. 12.5%, P<0.001) and had lower mean SUVmax (2.4 vs. 5.6, P<0.001). FDG-PET is not more accurate than BS for detecting bone metastasis in patients with UADT cancer. Positive findings on FDG-PET or BS require further confirmation.     

Assessment of 18F-fluorodeoxyglucose positron emission tomography combined with computed tomography in the preoperative management of patients with gastric cancer

Background

The significance of ¹⁸F-2-deoxy-2-fluoro-glucose positron emission tomography combined with computed tomography imaging (FDG-PET/CT) in the diagnosis of gastric cancer remains controversial. This study aimed to evaluate the efficacy of preoperative FDG-PET/CT in staging of gastric cancer.

Methods

FDG-PET/CT results for 90 patients with gastric cancer were retrospectively examined. For quantitative PET analysis, FDG uptake was assessed based on the maximum standardized uptake values (SUV_max).

Results

FDG-PET/CT detected the primary gastric cancer in 71 of the 90 patients (sensitivity 78.9 %). The median SUV_max was significantly higher in patients with T3/T4 disease than in those with T1/T2 (9.0 vs. 3.8; P < 0.001), in patients with distant metastasis than in those with no metastasis (9.5 vs. 7.7; P = 0.018), and with stage III/IV tumors than in those with stage I/II (9.0 vs. 4.7; P = 0.017). The SUV_max of the primary tumor was significantly correlated with tumor size (r = 0.461, P < 0.001). The sensitivity, specificity, and accuracy of FDG-PET/CT in assessing metastasis to regional lymph nodes were 64.5, 85.7, and 71.1 %, respectively.

Conclusions

FDG-PET/CT results are significantly associated with tumor progression in gastric cancer, and such findings can reliably identify cancer cell populations.     

Detection of unsuspected spinal cord compression in melanoma patients by 18F-fluorodeoxyglucose-positron emission tomography.

AIM: Positron emission tomography (PET) using (18)F-fluorodeoxyglucose can detect early or small metastatic deposits of melanoma and guide subsequent correlative anatomical imaging and treatment. The aim of this study was to assess the value of PET in demonstrating spinal cord compression by otherwise unsuspected metastatic disease. METHODS: Reports of 1365 PET studies performed on patients with melanoma were reviewed. Fifty patients considered to be at risk of spinal cord compression on the basis of PET were identified and 35 patients were analysed. Magnetic resonance imaging and computed tomography were used to confirm or refute the diagnosis. The symptoms and signs at the time of PET and follow-up status were compared between patients with and without confirmed spinal cord compression. RESULTS: In nine patients (26%) compression of the spinal cord or adjacent neurological structures was confirmed and eight of these patients had immediate treatment. Survival was poor in both patient groups, but three patients with confirmed compression maintained good neurological functional status following treatment. CONCLUSION: PET can detect imminent, unsuspected spinal cord compression in patients with metastatic melanoma. Immediate anatomical imaging of the spine is recommended in patients who have evidence of spinal cord compression on PET.     

A study on the clinical value of 18F-fluorodeoxyglucose positron emission tomography/computed tomography combined with serum squamous cell carcinoma antigen in diagnosing recurrence/metastases in patients with early metaphase cervical cancer

Cervical cancer (CC) is the most common female genital tract malignancy, with repercussions on the psychophysiological health of female patients. Patients with CC are faced with a high risk of postoperative recurrence and metastases. The present study aimed to evaluate the clinical value of 18F-fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) combined with serum squamous cell carcinoma antigen (SCC-Ag) in the diagnosis of postoperative recurrence/metastases in patients with early stage CC. This was a prospective follow-up study on 246 patients who received surgery for early stage CC. The results of clinical follow-up and pathological examination were taken as the gold standard. The diagnostic sensitivity, specificity, positive predictive value, negative predictive value and area under the receiver operating characteristic (ROC) curve were calculated for PET/CT, serum SCC-Ag determination and the combined PET/CT and serum SCC-Ag method. Results demonstrated that 90.11% patients completed the follow-up, and the median follow-up time was 22 months (range, 7–42 months). Tumor recurrence or metastasis was confirmed in a total of 137 patients (55.7%), including 18 deaths. The diagnostic sensitivity of PET/CT scan combined with serum SCC-Ag determination for postoperative metastases/recurrence in patients with early stage CC was 93.43% (95% CI, 0.875–0.967). The specificity was 92.67% (95% CI, 0.856–0.965), the positive predictive value was 94.12% (95% CI, 0.884–0.972), the negative predictive value was 91.81% (95% CI, 0.846–0.959) and the area under the ROC curve was 0.930±0.019 (95% CI, 0.893–0.968; P<0.001). The results also revealed that the serum SCC-Ag level was positively correlated with SUVmax (r=0.458; P<0.001). The results from the present study demonstrated that for patients with early metaphase CC, PET/CT scan combined with serum SCC-Ag determination during the follow-up was capable of earlier, more comprehensive and more accurate detection of recurrence/metastatic lesions, which is of high clinical application value.     

Value of fused positron emission tomography CT in detecting primaries in patients with primary unknown cervical lymph node metastasis

Objective: Identification of the primary tumour can prolong the life expectancy of patients with primary unknown cervical lymph node metastasis (PUCLNM) through targeted therapy. This study investigated the value of 18F‐fluorodeoxyglucose positron emission tomography/computed tomography (FDG PET‐CT) at identifying primaries in patients with PUCLNM. Methods: Twenty‐seven patients (21 males and 6 females, median age 48.2 ± 16.3, age range 30–73) with PUCLNM underwent FDG PET‐CT to search for the primary tumour, which could not be detected by conventional diagnostic modalities. The results were analysed and correlated with either pathological findings or clinical follow up. Results: Pathological FDG uptake suspicious for the primary was detected in 13 cases, while the primary tumour remained occult in 14 cases. Eleven of 13 patients with suspected primaries were confirmed by histological findings. One with a coexisting second tumour and three with unexpected distant metastases were found in patients with confirmed primaries. The most common primary location in patients with PUCLNM found in our study was nasopharynx. In those 14 patients with negative FDG PET‐CT results, only one patient had a primary malignancy that was proven histologically after endoscopy with biopsy during a period of clinical follow up. The sensitivity, specificity, accuracy and positive predictive values of FDG PET‐CT were 91.7, 86.7, 88.9 and 84.6%, respectively. Conclusion: FDG PET‐CT is a useful tool to help search for unknown primaries in patients with cervical lymph node metastasis and has an acceptable diagnostic yield for the detection of distant malignancies.     

原发灶不明颈淋巴结转移癌42例临床分析

目的探讨原发灶不明颈淋巴结转移癌的诊断、治疗方法与预后的影响因素。方法回顾分析我院1992年2月～1999年2月收治的42例原发灶不明颈淋巴结转移癌患者的临床资料。结果全组的1、3、5年生存率分别为71．4％(30／42)，45．2％(19／42)，33．3％(14／42．)。随诊中有14．3％(6／42．)的原发灶不明颈淋巴结转移癌患者发现了原发灶。结论影响原发灶不明颈淋巴结转移癌预后的主要因素是组织学类型，N分期，转移癌的部位，原发灶是否找到。对颈部转移性低分化癌、未分化癌或鳞癌应采用放射治疗，位于中上颈者应采用面颈联合野放射治疗，转移性腺癌应以手术治疗为主，晚期颈转移癌应采用化疗、放疗为主的综合治疗。锁骨上区转移癌应以化疗为首选。     

18 F-脱氧葡萄糖PET显像在原发灶不明转移癌中的应用

目的：探讨^18F-脱氧葡萄糖（FDG）正电子发射型体层摄影术（PET）全身显像在原发灶不明转移癌中的作用。方法：对29例原发灶不明转移癌患者行EDG PET全身显像，并与临床随诊、组织活检和手术病理结果对照。结果：29例原发灶不明转移癌患者，FDG PET发现可疑原发灶15例，其中13例为病理结果所证实，2例病理结果为阴性，FDG PET对原发灶的检出率为44．8％（13／29）。FDG PET全身显像另外检检出淋巴结转移和远地转移灶26个，CT和MRI只检出13个。14例FDG PET未确定原发灶者，经随访3－13个月,死亡率42．9％（6／14）。13例FDG PET确定原发灶者，经过有针对性的治疗，经随访2－13个月，死亡率为15．4％（2／13）。结论：FDG PET全身显像对原发灶不明转移癌原发灶的确定、临床分期、治疗方案的制定以及预后的改善均有一定的价值。     

Differentiating recurrent or residual nasopharyngeal carcinomas from post-radiotherapy changes with 18-fluoro-2-deoxyglucose positron emission tomography and thallium-201 single photon emission computed tomography in patients with indeterminate computed tomography findings

The aim of this study was to compare the accuracy of 18-fluoro-2-deoxyglucose (FDG) positron emission tomography (PET) and thallium-201 (Tl-201) single photon emission computed tomography (SPECT) in differentiating recurrent/residual nasopharyngeal carcinomas (NPC) from post-radiotherapy (RT) changes in patients with indeterminate computed tomography (CT) findings. Twenty NPC patients with indeterminate CT findings were included at least 4 months after RT. CT, FDG-PET, Tl-201 SPECT and biopsy were performed within 1 week. The final diagnoses were based on biopsy findings and clinical follow-up for at least 6 months. For differentiating recurrent/residual NPC from post-RT changes in patients with indeterminate CT findings, the sensitivity, specificity and accuracy of FDG-PET were 100.0%, 92.3% and 96.0%, respectively. The sensitivity, specificity and accuracy of Tl-201 SPECT were 91.7%, 92.3% and 92.0%, respectively. Based on this study's findings, we can conclude FDG-PET is more sensitive but equally specific as Tl-201 SPECT is differentiating recurrent/residual NPC from post-RT changes in patients with indeterminate CT findings.     

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.     

Unique intense uptake demonstrated by (18)F-FDG positron emission tomography/computed tomography in primary pancreatic lymphoma: A case report

Patients with primary pancreatic lymphoma (PPL), which is rare, require a different therapeutic approach and have a better prognosis than those with pancreatic cancer. However, conventional imaging modalities alone are not able to differentiate between pancreatic cancer and other rare tumors such as PPL, although the accurate diagnosis of PPL is crucial. The development of new modalities such as F-18 2'-deoxy-2fluoro-D-glucose (FDG) positron emission tomography combined with computed tomography (PET/CT) contributes to the evaluation of lymphoma staging. However, few reports are currently available regarding PET/CT findings in PPL. In this study, a 56-year old man with PPL was examined using FDG PET/CT imaging, which showed the unique intense uptake of FDG in the pancreas with atypical findings of malignancy in the CT scan and magnetic resonance images.