Value of 11C-choline PET and contrast-enhanced CT for staging of bladder cancer: correlation with histopathologic findings.

Lymph node involvement is a major prognostic factor in bladder cancer, but the accuracy of conventional imaging modalities for the prediction of regional and distant metastatic diseases is limited. This study was performed to compare the diagnostic accuracies of contrast-enhanced CT and PET with (11)C-choline for the staging of urothelial bladder cancer. METHODS: Twenty-seven patients (median age, 69.1 y) who had urothelial bladder cancer and who were referred for radical cystectomy and pelvic lymph node dissection (PLND) on the basis of a histologic evaluation after transurethral resection of bladder cancer (TURB) were studied. PET scanning, using 2 multiring whole-body tomographs, was performed 5 min after intravenous injection of approximately 370-500 MBq of (11)C-choline. In addition, conventional bone scintigraphy and contrast-enhanced CT were performed. After imaging, cystectomy and PLND were performed in all patients. Pathologic (11)C-choline uptake that could not be explained by intestinal activity was noted as a positive result. Node positivity was determined by size on CT: nodes measuring more than 1 cm in the long axis were described as being positive for tumor. Histopathologic findings were used as a reference. RESULTS: The presence of residual bladder cancer (pTa-pT4) was correctly detected in 21 of 25 histologically tumor-positive patients (84%) by CT and in 24 of 25 patients (96%) by (11)C-choline PET. Lymph node involvement was correctly detected in 4 of 8 patients (50%) by CT and in 5 of 8 patients (62%) by (11)C-choline PET. The median size of the 3 nodes with false-negative PET results was 9 mm (range, 6-21 mm), and the median size of the metastatic lesions within the lymph nodes was 3 mm (range, 1-15 mm). CT resulted in 6 (22%) false-positive lymph nodes, whereas none was demonstrated by (11)C-choline PET; these data indicated a significantly higher accuracy of PET than of CT (P < 0.01). Both modalities missed a small peritoneal metastasis verified by histologic evaluation. No positive results were obtained from bone scintigraphy. CONCLUSION: These preliminary data suggest that (11)C-choline PET is comparable to CT for detecting residual bladder cancer after TURB but appears to be superior to CT for the evaluation of potential additional lymph node metastases. (11)C-choline PET should be further evaluated for staging in patients who have bladder cancer and who are scheduled for radical cystectomy.     

A comparative study of 11C-choline PET and [18F]fluorodeoxyglucose PET in the evaluation of lung cancer

The purpose of this study was to compare the diagnostic value of 11C-choline positron emission tomography (PET) and [18F]fluorodeoxyglucose (FDG) PET imaging in the detection of primary lung cancer and mediastinal lymph node metastases. Seventeen patients with histologically proven primary lung cancer were examined with both 11C-choline and FDG PET within a week of each study. Lung cancers were analysed visually and semiquantitatively using the ratio of tumour-to-normal radioactivity (T/N ratio) and standardized uptake value (SUV). Mediastinal lymph node metastases were analysed visually. Although both techniques delineated focal lesions with an increase in tracer accumulation in 13 patients, FDG PET identified three additional patients in whom 11C-choline PET did not visualize any lesion. In the detection of lung cancer <2 cm in size, FDG PET provided higher sensitivity (six of seven, 85.7%) than 11C-choline PET (four of seven, 57.1%). The T/N ratio and SUV were significantly higher with FDG PET (T/N ratio, 7.43+/-6.22; SUV, 4.05+/-3.05) than these were with 11C-choline PET (T/N ratio, 2.93+/-1.19; SUV, 2.93+/-0.79) (P<0.001). There was a significant positive correlation between the T/N ratios and SUVs of FDG and 11C-choline. In the assessment of mediastinal lymph node involvement, FDG PET detected lymph node metastases in two patients who were negative on 11C-choline PET, whereas both techniques could not detect tumour involvement in one patient. Both techniques have clinical value for the non-invasive detection of primary lung cancer that is 2 cm or greater in size. However, FDG PET is superior to 11C-choline PET in the detection of lung cancer that is less than 2 cm in diameter and in mediastinal lymph node metastases.     

PET在前列腺癌中的应用

前列腺癌是老年男性最常见的恶性肿瘤之一,PET在其早期诊断和准确分期方面具有重要价值。18F-氟代脱氧葡萄糖(18F-FDG)PET对前列腺癌的检出并不敏感,也不能可靠进行淋巴结分期,但18F-FDG摄取与疾病进展程度相关。11C-胆碱PET诊断前列腺癌的准确率高,在淋巴结及骨转移的检出方面也明显优于18F-FDGPET,但其半衰期短而限制了临床应用。18F-胆碱的肿瘤摄取与11C-胆碱相似,但在泌尿系统排泄较高。其他示踪剂如11C-乙酸、11C-甲硫氨酸、18F标记的雄激素等在前列腺癌的诊断、分期及疗效评价方面也具有一定价值。     

Detection and localization of prostate cancer: correlation of (11)C-choline PET/CT with histopathologic step-section analysis.

This study evaluated the potential usefulness of (11)C-choline PET/CT for detection and localization of tumors within the prostate. We used the results of step-section histopathologic examination as the standard of reference. METHODS: The results were analyzed on a sextant basis. We reviewed the results of the (11)C-choline PET/CT scans of 36 patients with prostate cancer and of 5 control subjects with bladder cancer. All patients underwent (11)C-choline PET/CT and, subsequently, radical prostatectomy with lymph node dissection within 1 mo. (11)C-Choline PET/CT scans were obtained 5-10 min after intravenous injection of 370-555 MBq of (11)C-choline. Images were reviewed visually and semiquantitatively using maximum SUV and tumor-to-background ratio. RESULTS: On a sextant basis, histopathologic analysis detected cancer foci in 143 of 216 sextants; high-grade prostate intraepithelial neoplasm foci were detected in 89 of 216 sextants (in 59 sextants in association with carcinoma, in 30 sextants alone), acute prostatitis was detected in 7 of 216 sextants (in 3 sextants in association with carcinoma, in 4 sextants alone), and 39 of 216 sextants were normal. PET/CT demonstrated focal (11)C-choline uptake in 108 sextants (94 of which involved tumor), and 108 sextants showed no abnormal (11)C-choline uptake (49 of which were false negative). The sensitivity, specificity, accuracy, positive predictive value, and negative predictive value of PET/CT were 66%, 81%, 71%, 87%, and 55%, respectively. In the 5 control subjects, high-grade prostate intraepithelial neoplasm was detected at histologic examination in 16 of 30 sextants. PET/CT showed increased (11)C-choline uptake in 5 of 16 sextants. CONCLUSION: This study demonstrated the feasibility of using (11)C-choline PET/CT to identify cancer foci within the prostate. However, we also found that (11)C-choline PET/CT has a relative high rate of false-negative results on a sextant basis and that prostatic disorders other than cancer may accumulate (11)C-choline. Therefore, our data do not support the routine use of PET/CT with (11)C-choline as a first-line screening procedure for prostate cancer in men at high risk.     

11C-胆碱PET/CT显像在肺癌中的应用价值及其机理的研究

目的探讨11 C-胆碱PET/CT显像在肺癌中的应用价值及胆碱代谢机理。方法目测法和半定量法分析38例可疑肺癌患者PET/CT显像结果;RT-PCR和Western blot方法进行分子生物学检测。结果手术病理证实29例为肺癌,3例为良性病变。6例因发生远处转移未行手术。肺癌原发病灶、纵隔及肺门淋巴结转移及远处转移灶均显示放射性摄取明显增高。目测法及半定量分析法均显示良、恶性病变无显著性差异。鳞癌、腺癌、不典型类癌的11 C-胆碱摄取值相比也不具有显著性差异。12例肺癌组织细胞中,9例Chok mRNA及蛋白质的表达比正常肺组织升高,5例ChATmRNA及蛋白质表达升高,其中5例Chok及ChAT表达均升高。结论 11 C-胆碱PET/CT显像能够发现肺癌原发病灶、纵隔及肺门淋巴结转移及远处转移灶,有助于准确临床分期;但不能有效鉴别肺部病灶的良恶性。肺癌组织细胞中不仅有磷酸化途径的增强,而且存在乙酰化途径。     

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.     

Routine (18)F-FDG PET preoperative staging of colorectal cancer: comparison with conventional staging and its impact on treatment decision making.

The preoperative staging of colorectal cancer (CRC) with (18)F-FDG PET is not as yet generally considered to be evidence based. We have found only 1 study that evaluated (18)F-FDG PET in a nonselected population with proven CRC. Several other studies have concentrated on more advanced disease. The aim of this study was to assess the potential clinical benefit of (18)F-FDG PET in the routine staging of CRC. METHODS: Thirty-eight consecutive patients who had had CRC histologically proven by colonoscopy underwent prospective preoperative staging by plain chest radiography, sonography, CT, and (18)F-FDG PET. Sensitivity, specificity, and accuracy were retrospectively assessed by comparison with the histologic results after surgery (36 patients) or clinical follow-up (2 inoperable cases-both patients died within 1 y of the PET examination). The impact of (18)F-FDG PET on therapeutic decision making was evaluated by comparing medical records before and after (18)F-FDG PET. RESULTS: (18)F-FDG PET correctly detected 95% of primary tumors, whereas CT and sonography correctly detected only 49% and 14%, respectively. Lymph nodes were involved in 7 patients. The sensitivity, specificity, and accuracy of (18)F-FDG PET were 29%, 88%, and 75%, respectively. CT and sonography did not reveal any lymph node involvement. Liver metastases were present in 9 patients. (18)F-FDG PET, CT, and sonography had a sensitivity of 78%, 67%, and 25%, respectively; a specificity of 96%, 100%, and 100%, respectively; and an accuracy of 91%, 91%, and 81%, respectively. (18)F-FDG PET revealed further lesions in 11 patients. Levels of carcinoembryonic antigen and carbohydrate antigen 19-9 tumor markers were elevated in, respectively, only 33% and 8% of cases of proven CRC. (18)F-FDG PET changed the treatment modality for 8% and the range of surgery for 13% of patients. In total, (18)F-FDG PET changed the method of treatment for 16% of patients. CONCLUSION: Plain chest radiography and sonography did not bring any clinical benefits. No correlation was found between the level of tumor markers and the stage of disease. CT is necessary for confirmation of PET findings at extraabdominal sites (PET-guided CT) and for their morphologic specification at abdominal and pelvic sites before an operation. (18)F-FDG PET is the best method for the staging of CRC in all localities, despite the high rate of false-negative PET findings in patients with lymph node involvement. PET should be performed as a first examination after verification of CRC. We propose a PET/CT hybrid system as optimal in the staging of CRC.     

Preoperative lymph node staging in patients with primary prostate cancer: comparison and correlation of quantitative imaging parameters in diffusion-weighted imaging and 11C-choline PET/CT

Purpose

To compare the diagnostic performance of DWI and 11C-choline PET/CT in the assessment of preoperative lymph node status in patients with primary prostate cancer.

Material and methods

Thirty-three patients underwent DWI and 11C-choline PET/CT prior to prostatectomy and extended pelvic lymph node dissection. Mean standardised uptake value (SUV_mean) and mean apparent diffusion coefficient (ADC) of 76 identified lymph nodes (LN) were measured and correlated with histopathology. ADC values and SUVs were compared using linear regression analysis.

Results

A significant difference between benign and malignant LN was observed for ADC values (1.17 vs. 0.96?×?10^-3 mm²/s; P?<?0.001) and SUV_mean (1.61 vs. 3.20; P?<?0.001). ROC analysis revealed an optimal ADC threshold of 1.01?×?10^-3 mm²/s for differentiating benign from malignant LN with corresponding sensitivity/specificity of 69.70 %/78.57 % and an area under the curve (AUC) of 0.785. The optimal threshold for SUV_mean was 2.5 with corresponding sensitivity/specificity of 69.72 %/90.48 % and with an AUC of 0.832. ADC values and SUV_mean showed a moderate significant inverse correlation (r?=?-0.63).

Conclusion

Both modalities reveal similar moderate diagnostic performance for preoperative lymph node staging of prostate cancer, not justifying their application in routine clinical practice at this time. The only moderate inverse correlation between ADC values and SUV_mean suggests that both imaging parameters might provide complementary information on tumour biology.

Key Points

? Conventional imaging shows low performance for lymph node staging in prostate cancer. ? DWI and 11C-choline PET/CT both provide additional functional information ? Both functional modalities reveal only moderate diagnostic performance.     

Lymph node metastasis in patients with clinical early-stage cervical cancer: detection with integrated FDG PET/CT

PURPOSE: To prospectively determine the accuracy of combination positron emission tomography-computed tomography (PET/CT) in lymph node staging in patients with early-stage cervical cancer, with histopathologic results as the reference standard. MATERIALS AND METHODS: The study was institutional review board approved, and all patients gave informed consent. Forty-seven consecutive women aged 29-71 years with clinical stage IA or IB cervical carcinoma were included in the study. All 47 patients were scheduled for radical hysterectomy with pelvic lymph node dissection. Before surgery, all patients underwent fluorine 18 fluorodeoxyglucose (FDG) PET/CT. PET/CT findings were interpreted by two readers in consensus and then compared with histopathologic results. At histopathologic examination, the dissected lymph nodes were classified as nonmetastatic or metastatic. RESULTS: Fifteen (32%) patients had metastatic lymph nodes at histopathologic examination, and 32 (68%) had no histopathologically confirmed nodal metastasis. Of the total 1081 lymph nodes histopathologically sampled, 18 were found to be positive for malignant cells. The overall node-based sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy of PET/CT were 72% (13 of 18), 99.7% (1060 of 1063), 81% (13 of 16), 99.5% (1060 of 1065), and 99.3% (1073 of 1081), respectively. Corresponding values for PET/CT-based diagnosis of lymph nodes larger than 0.5 cm in diameter were 100% (13 of 13), 99.6% (675 of 678), 81% (13 of 16), 100% (675 of 675), and 99.6% (688 of 691), respectively. The overall patient-based sensitivity, specificity, PPV, NPV, and accuracy of PET/CT were 73% (11 of 15), 97% (31 of 32), 92% (11 of 12), 89% (31 of 35), and 89% (42 of 47), respectively. CONCLUSION: PET/CT proved to be valuable for lymph node staging in patients with early-stage cervical cancer, with short-axis diameter greater than 0.5 cm being the size threshold for accurate depiction of metastatic nodes.     

11C-Choline PET/CT in patients with hormone-resistant prostate cancer showing biochemical relapse after radical prostatectomy

Purpose

To determine the diagnostic efficacy of ¹¹C-choline PET/CT in patients with prostate cancer (PC) after radical prostatectomy who presented with increasing PSA levels during follow-up in spite of being on hormone treatment (HT), and therefore showing HT resistance.

Methods

We evaluated a large series of 157 consecutive PC patients previously treated by radical prostatectomy who presented with biochemical recurrence with increasing PSA levels in spite of ongoing HT (HT-resistant patients). At the time of ¹¹C-choline PET/CT, the mean value of trigger PSA level was 8.3 (range ?0.2 – 60.6 ng/mL), the mean PSA doubling time (PSAdt) was 5.3? (range ?0.4 – 35 months), and the mean PSA velocity (PSAvel) was 22.1 ng/mL/year (range 0.12 – 82 ng/mL/year). ¹¹C-Choline PET/CT was performed following a standard procedure at our centre to investigate increasing PSA levels, either as the first imaging procedure or in patients with negative conventional imaging. At the time of ¹¹C-choline PET/CT all patients were receiving HT (61 were receiving monotherapy and 96 multidrug therapy). PET-positive findings were validated by: (a) transrectal US-guided biopsy in patients with recurrence in the prostatic bed, (b) surgical pelvic lymphadenectomy, (c) other imaging modalities, including repeated ¹¹C-choline PET/CT, performed during a minimum follow-up of 12-months.

Results

¹¹C-Choline PET/CT showed positive findings in 104 of the 157 patients (66 %). ¹¹C-choline PET/CT detected: a single lesion in 40 patients (7 in the prostate bed, 10 in lymph nodes, 22 in bone, 1 at another site); two lesions in 18 patients (7 in lymph nodes, 7 in bone, 4 in both lymph nodes and bone); three or four lesions in 7 patients (4 in lymph nodes, 2 in bone, 1 at another site); and more than four lesions in the remaining 39 patients (2 in the prostate bed, 12 in lymph nodes, 12 in bone, 11 in both lymph nodes and bone, 2 at other sites). In ¹¹C-choline PET-negative patients, the mean values of trigger PSA, PSAdt and PSAvel were 3.8 ng/mL (range 0.2 – 11.9 ng/mL) 7.0 months (range 1.21 – 35 months) and 5.8 ng/mL/year (range 0.12 – 30.1) respectively, while in ¹¹C-Choline-PET-positive patients they were 10.5 ng/mL (range 0.2 – 60.6), 4.4 months (range 0.4 – 19.7) and 15.9 ng/mL/year (range 0.5 – 82.0) respectively. The differences between PET-negative and PET-positive patients were statistically significant for all these parameters: trigger PSA, p?<?0.01; PSAdt, p?<?0.01; PSAvel, p?=?0.03.

Conclusion

In our patient population, ¹¹C-choline PET/CT was able to detect relapsed disease in a large proportion of HT-resistant PC patients during HT. These data, obtained in a large series, suggest that HT withdrawal before performing a ¹¹C-choline PET/CT scan may not be necessary for the detection of recurrent disease if PSA levels are increasing and PSA kinetics are rapid.     

Experience with carbon-11 choline positron emission tomography in prostate carcinoma

We investigated the potential of carbon-11 choline positron emission tomography (PET) for the detection of lymph node and bone metastases in prostate cancer. A total of 23 patients were studied (known metastases: 8; suspicion of metastases: 3; primary staging: 12). Whole-body PET imaging was performed 5 min after injection of the tracer and completed within 1 h. Focally increased tracer uptake in bone or abdominal lymph node regions was interpreted as representing tumour involvement. All known bone and lymph node metastases could be recognized by [11C]choline PET. One out of ten negative scans for primary staging was false-negative (lymph node <1 cm) and one out of two positive scans was false-positive with regard to lymph node involvement (focal bowel activity). It is concluded that [11C]choline PET is a promising new tool for the primary staging of prostate cancer, with lymph node and bone metastases demonstrating high tracer uptake. Therapeutic management could be influenced by these results in that the technique may permit avoidance of surgical lymph node exploration.     

Comparison of <Superscript>68</Superscript>Ga-labelled PSMA-11 and <Superscript>11</Superscript>C-choline in the detection of prostate cancer metastases by PET/CT

Purpose

Prostate-specific membrane antigen (PSMA) is expressed ubiquitously on the membrane of most prostate tumors and its metastasis. While PET/CT using ¹¹C-choline was considered as the gold standard in the staging of prostate cancer, PET with radiolabelled PSMA ligands was introduced into the clinic in recent years. Our aim was to compare the PSMA ligand ⁶⁸Ga-PSMA-11 with ¹¹C-choline in patients with primary and recurrent prostate cancer.

Methods

123 patients underwent a whole-body PET/CT examination using ⁶⁸Ga-PSMA-11 and ¹¹C-choline. Suspicious lesions were evaluated visually and semiquantitatively (SUVavg). Out of these, 103 suffered from a confirmed biochemical relapse after prostatectomy and/or radiotherapy (mean PSA level of 4.5 ng/ml), while 20 patients underwent primary staging.

Results

In 67 patients with biochemical relapse, we detected 458 lymph nodes suspicious for metastasis. PET using ⁶⁸Ga-PSMA-11 showed a significantly higher uptake and detection rate than ¹¹C-choline PET. Also ⁶⁸Ga-PSMA-11 PET identified significantly more patients with suspicious lymph nodes as well as affected lymph nodes regions especially at low PSA levels. Bone lesions suspicious for prostate cancer metastasis were revealed in 36 patients’ biochemical relapse. Significantly more bone lesions were detected by ⁶⁸Ga-PSMA-11, but only 3 patients had only PSMA-positive bone lesions. Nevertheless, we detected also 29 suspicious lymph nodes and 8 bone lesions, which were only positive as per ¹¹C-choline PET. These findings led to crucial differences in the TNM classification and the identification of oligometastatic patients. In the patients who underwent initial staging, all primary tumors showed uptake of both tracers. Although significantly more suspicious lymph nodes and bone lesions were identified, only 2 patients presented with bone lesions only detected by ⁶⁸Ga-PSMA-11 PET.

Conclusion

Thus, PET using ⁶⁸Ga-PSMA-11 showed a higher detection rate than ¹¹C-choline PET for lymph nodes as well as bone lesions. However, we found lymph nodes and bone lesions which were not concordant applying both tracers.

     

Value of <Superscript>11</Superscript>C-choline PET and PET/CT in patients with suspected prostate cancer

Purpose: The value and limitations of ¹¹C-choline PET and PET/CT for the detection of prostate cancer remain controversial. The aim of this study was to investigate the diagnostic efficacy of ¹¹C-choline PET and PET/CT in a large group of patients with suspected prostate cancer. Methods: Fifty-eight patients with clinical suspicion of prostate cancer underwent ¹¹C-choline PET (25/58, Siemens ECAT Exact HR+) or PET/CT (33/58, Philips Gemini) scanning. On average, 500 MBq of ¹¹C-choline was administered intravenously. Studies were interpreted by raters blinded to clinical information and other diagnostic procedures. Qualitative image analysis as well as semiquantitative SUV measurement was carried out. The reference standard was histopathological examination of resection specimens or biopsy. Results: Prevalence of prostate cancer in this selected patient population was 63.8% (37/58). ¹¹C-choline PET and PET/CT showed a sensitivity of 86.5% (32/37) and a specificity of 61.9% (13/21) in the detection of the primary malignancy. With regard to metastatic spread, PET showed a per-patient sensitivity of 81.8% (9/11) and produced no false positive findings. Conclusion: Based on our findings, differentiation between benign prostatic changes, such as benign prostatic hyperplasia or prostatitis, and prostate cancer is feasible in the majority of cases when image interpretation is primarily based on qualitative characteristics. SUV_max may serve as guidance. False positive findings may occur due to an overlap of ¹¹C-choline uptake between benign and malignant processes. By providing functional information regarding both the primary malignancy and its metastases, ¹¹C-choline PET may prove to be a useful method for staging prostate cancer.     

Experience with carbon-11 choline positron emission tomography in prostate carcinoma

We investigated the potential of carbon-11 choline positron emission tomography (PET) for the detection of lymph node and bone metastases in prostate cancer. A total of 23 patients were studied (known metastases: 8; suspicion of metastases: 3; primary staging: 12). Whole-body PET imaging was performed 5 min after injection of the tracer and completed within 1 h. Focally increased tracer uptake in bone or abdominal lymph node regions was interpreted as representing tumour involvement. All known bone and lymph node metastases could be recognized by [¹¹C]choline PET. One out of ten negative scans for primary staging was false-negative (lymph node <1 cm) and one out of two positive scans was false-positive with regard to lymph node involvement (focal bowel activity). It is concluded that [¹¹C]choline PET is a promising new tool for the primary staging of prostate cancer, with lymph node and bone metastases demonstrating high tracer uptake. Therapeutic management could be influenced by these results in that the technique may permit avoidance of surgical lymph node exploration.     

Usefulness of PET with 11C-methionine for the detection of hilar and mediastinal lymph node metastasis in lung cancer.

We retrospectively evaluated the usefulness of PET with 11C-methionine (methionine PET) for the diagnosis of lymph node metastases in patients with lung cancer. METHODS: Methionine PET and CT were performed before surgical intervention in 41 patients with primary lung cancer. We evaluated individual lymph nodes by methionine PET along with corresponding CT images. The 11C-methionine accumulation of lymph nodes was assessed semiquantitatively by analysis of the tumor-to-muscle ratio (TMR) and was compared with CT and histological diagnoses. RESULTS: A total of 126 lymph nodes, 36 of which were histologically diagnosed as metastatic, were assessed by CT and methionine PET. The TMR in metastatic lymph nodes (n = 36) was 5.15+/-1.69, whereas that of nonmetastatic lymph nodes (n = 90) was 2.91+/-0.76; this difference was significant (P < 0.0001). The most adequate TMR cutoff value for diagnosis of metastasis based on the results of receiver operating characteristic curve analysis was 4.1. The positive and negative predictive values, sensitivity, specificity, and accuracy of methionine PET were 79.5%, 94.3%, 86.1%, 91.1%, and 89.7%, respectively, and were superior to those of CT (57.6%, P = 0.04; 81.7%, P = 0.008; 52.8%, P = 0.002; 84.4%, NS; and 75.4%, P = 0.002, respectively). All positive nodes that were shown to be true-positive by CT, and 12 of 17 false-negatives on CT were correctly diagnosed by PET. Ten of 14 lymph nodes that were false-positive on CT were also correctly diagnosed by PET. CONCLUSION: Methionine PET appears to be superior to CT for the diagnosis of lymph node metastasis in lung cancer patients. The high negative predictive value of methionine PET suggests that cases in which lymph nodes are enlarged on CT with negative PET analysis may be diagnosed as negative for metastasis.     

Assessment of cervical lymph node metastases using FDG-PET in patients with head and neck cancer

OBJECTIVE: To evaluate the diagnostic accuracy of fluorodeoxyglucose positron emission tomography (FDG-PET) relative to computed tomography (CT) for detecting metastatic cervical lymph nodes in patients with squamous cell carcinoma of the head and neck (HNSCC), and to ascertain the factors that affect this accuracy. METHODS: A total of 1076 lymph nodes obtained from 35 neck dissections in 26 HNSCC patients who preoperatively underwent both FDG-PET and CT were retrospectively analyzed. For pathological metastatic lymph nodes, the lymph node size (short-axis diameter), the ratio of intranodal tumor deposits, and the size of intranodal tumor deposits (maximum diameter of metastatic foci in each lymph node) were histologically recorded. RESULTS: Forty-six lymph nodes from 23 neck sides were pathologically diagnosed metastases. The sensitivity, specificity, accuracy, positive predictive value, and negative predictive value of FDG-PET evaluated individually per neck side were 74%, 92%, 80%, 94%, and 65%, respectively, whereas those of CT were 78%, 58%, 71%, 78%, and 58%, respectively. FDG-PET detected 100% of metastatic lymph nodes > or =10 mm, intranodal tumor deposits > or =9 mm, and intranodal tumor deposits with a ratio >75%, whereas no nodes or tumor deposits smaller than 5 mm were detected. The spatial resolution limitations of FDG-PET were responsible for 16 of 20 (80%) false-negative PET results in lymph nodes. CONCLUSIONS: FDG-PET is a useful tool for preoperative evaluation of the neck because it accurately detects metastatic lymph nodes > or =10 mm and has fewer false-positive cases than CT. The high specificity of FDG-PET for lymph node metastases may play an important role in avoiding unnecessary neck dissection.     

18F-FDG PET/CT在宫颈癌诊断中的应用

目的 探讨18F-脱氧葡萄糖(FDG) PET/CT在宫颈癌诊断及其复发、转移灶探测中的应用价值.方法 88例患者行腹部或全身18F-FDG PET/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.病灶根据病理检查、多种影像诊断技术及临床随访确诊,随访时间均为6个月～3年.结果 30例初诊者中,PET/CT诊断宫颈癌的灵敏度、特异性和准确性分别为17/19,10/11和27/30(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10/11,47/47(100.0%)和57/58(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%;转移灶以盆腹腔淋巴结为主,39.0%有盆腔淋巴结转移,27.3%有腹膜后淋巴结转移,所有淋巴结转移患者中PET/CT发现26.8%病灶直径＜1.0cm.28.6%(22/77)的患者PET/CT发现腹腔外远处转移灶.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.结论 18F-FDG PET/CT显像在宫颈癌的诊断及其复发、转移灶探测中有良好的应用价值,尤其是对远处转移灶和小淋巴结转移灶的检测,可使临床分期更准确.     

Imaging of lung cancer with fluorine-18 fluorodeoxyglucose: comparison of a dual-head gamma camera in coincidence mode with a full-ring positron emission tomography system

Dual-head gamma cameras operated in coincidence mode are a new approach for tumour imaging using fluorine-18 fluorodeoxyglucose (FDG). The aim of this study was to assess the diagnostic accuracy of such a camera system in comparison with a full-ring positron emission tomography (PET) system in patients with lung cancer. Twenty-seven patients (1 female, 26 males, age 62+/-9 years) with lung cancer or indeterminate pulmonary nodules were studied on the same day with a full-ring PET scanner (Siemens ECAT EXACT) and a coincidence gamma camera system (ADAC Vertex MCD). Sixty minutes after injection of 185-370 MBq FDG, a scan of the chest was performed with the full-ring system. Approximately 2 h p.i., the coincidence camera study was performed. Coincidence gamma camera (CGC) and PET images with (PETac) and without attenuation correction (PETnac) were analysed independently by two blinded observers. In addition, FDG uptake in primary tumours and involved lymph nodes was quantified relative to normal contralateral lung (T/L ratios). All primary tumours were histologically proven. The lymph node status was histologically determined in 23 patients. In four patients, no lymph node sampling was performed because of extensive disease or concurrent illnesses. In the 27 patients, 25 primary lung cancers and two metastatic lesions were histologically diagnosed. The number of coincidences per centimetre axial field of view was 3.33+/-0. 93x10(5) for the CGC and 1.09+/-0.36x10(6) for the dedicated PET system. All primary tumours (size: 4.6+/-2.6 cm) were correctly identified in the CGC and dedicated PET studies. T/L ratios were 4. 7+/-2.5 for CGC and 6.9+/-2.8 for PETnac (P <0.001). Histopathological evaluation revealed lymph node metastases in 11 of 88 sampled lymph node stations (size: 2.3+/-1.0 cm). All lymph node metastases were identified in the PETac studies, while PETnac detected 10/11 and CGC 8/11. For positive lymph nodes that were visible in CGC and PETnac studies, T/L ratios were 3.7+/-2.3 for CGC and 6.6+/-3.1 for PETnac (P=0.02). The diameters of false-negative lymph nodes in the CGC studies were 0.75, 1.5 and 2 cm. False-positive FDG uptake in lymph nodes was found in two patients with all three imaging methods. For all lesions combined, T/L ratios in CGC relative to PETnac studies decreased significantly with decreasing lesion size (r=0.62; P<0.001). In conclusion, compared with a full-ring PET system the sensitivity of CGC imaging for detection of lung cancer is limited by a lower image contrast which deteriorates with decreasing lesion size. Nevertheless, the ability of CGC imaging to detect pulmonary lesions with a diameter of at least 2 cm appears to be similar to that of a full-ring system. Both systems provide a similar specificity for the evaluation of lymph node involvement.     

The additional value of FDG PET imaging for distinguishing N0 or N1 from N2 stage in preoperative staging of non-small cell lung cancer in region where the prevalence of inflammatory lung disease is high

PURPOSE: The aim of this study was to evaluate the efficacy of PET imaging and compare it with the performance of CT in mediastinal and hilar lymph node staging in potentially operable non-small cell lung cancer (NSCLC). METHODS: Fifty-nine patients with potentially resectable NSCLC who underwent preoperative PET and CT imaging were enrolled into this prospective study. All patients underwent surgical evaluation by means of mediastinoscopy with mediastinal lymph node sampling (14 patients) or thoracotomy (45 patients). RESULTS: The prevalence of lymph node metastases was 53%. Overall, the sensitivity, specificity, accuracy, PPV, and NPV of PET were 79%, 76%, 78%, 86%, and 76% for N0 and N1 lymph nodes and 76%, 79%, 80%, 67%, and 83% for N2 lymph nodes, while those values for CT were 66%, 43%, 58%, 68%, and 43% for N0 and N1 stations and 43%, 66%, 54%, 41%, and 66% for N2 lymph nodes, respectively. PET correctly differentiated cases with mediastinal lymph node involvement (N2) from those without such involvement (N0 or N1) in 76% of cases. Statistical analysis of the diagnostic accuracy of nodal involvement showed that PET improves diagnostic accuracy significantly in the detection of both N0 or N1 and N2 status in the individual patient based on analysis, compared with CT (P < 0.01 and P < 0.01, respectively). When preoperative nodal staging was compared with postoperative histopathological staging, 38 (65%) patients were correctly staged, 9 (15%) were overstaged, and 12 (20%) were understaged by PET, while 29 patients (49%) were correctly staged, 13 (22%) were overstaged, and 17 (29%) were understaged by CT. CONCLUSION: It has been clearly shown that PET is more accurate than CT for the differentiation of N0 or N1 from N2 disease in patients with NSCLC. However, PET imaging alone does not appear to be sufficient to replace mediastinoscopy for mediastinal staging in patients with lung cancer, especially in geographic regions with high granulomatous or inflammatory mediastinal disease prevalence.     

Prospective comparison of 18F-FDG PET with conventional imaging modalities (CT, MRI, US) in lymph node staging of head and neck cancer

The aims of this study were to investigate the detection of cervical lymph node metastases of head and neck cancer by positron emission tomographic (PET) imaging with fluorine-18 fluorodeoxyglucose (FDG) and to perform a prospective comparison with computed tomography (CT), magnetic resonance imaging (MRI), sonographic and histopathological findings. Sixty patients with histologically proven squamous cell carcinoma were studied by PET imaging before surgery. Preoperative endoscopy (including biopsy), CT, MRI and sonography of the cervical region were performed in all patients within 2 weeks preceding ¹⁸F-FDG whole-body PET. FDG PET images were analysed visually and quantitatively for objective assessment of regional tracer uptake. Histopathology of the resected neck specimens revealed a total of 1284 lymph nodes, 117 of which showed metastatic involvement. Based on histopathological findings, FDG PET correctly identified lymph node metastases with a sensitivity of 90% and a specificity of 94% (P<10^–6). CT and MRI visualized histologically proven lymph node metastases with a sensitivity of 82% (specificity 85%) and 80% (specificity 79%), respectively (P<10^–6). Sonography revealed a sensitivity of 72% (P<10^–6). The comparison of ¹⁸F-FDG PET with conventional imaging modalities demonstrated statistically significant correlations (PET vs CT, P = 0.017; PET vs MRI, P = 0.012; PET vs sonography, P = 0.0001). Quantitative analysis of FDG uptake in lymph node metastases using body weight-based standardized uptake values (SUV_BW) showed no significant correlation between FDG uptake (3.7±2.0) and histological grading of tumour-involved lymph nodes (P = 0.9). Interestingly, benign lymph nodes had increased FDG uptake as a result of inflammatory reactions (SUV_BW-range: 2–15.8). This prospective, histopathologically controlled study confirms FDG PET as the procedure with the highest sensitivity and specificity for detecting lymph node metastases of head and neck cancer and has become a routine method in our University Medical Center. Furthermore, the optimal diagnostic modality may be a fusion image showing the increased metabolism of the tumour and the anatomical localization. Received 17 February and in revised form 12 June 1998