Usefulness of PET–CT in the assessment of suspected recurrent colorectal carcinoma

Purpose

To evaluate the usefulness of PET/CT in detecting recurrent colorectal carcinoma (CRCR) in patients subsequent to colonic resection or rectal amputation and to compare it with the PET part of integrated FDG-PET/CT.

Materials and methods

PET/CTs from 32 patients with suspected CRCR were studied. Histology, clinical follow-up and additional imaging served as the gold standard. The sensitivity, specificity, positive and negative predictive values (PPV, NPV), and accuracy of PET as well as integrated PET/CT were calculated and compared for each of (a) intra-abdominal extra-hepatic recurrences, (b) extra-abdominal and/or hepatic recurrences, and (c) any form of CRCR.

Results

PPV, sensitivity, NPV, specificity and accuracy of PET in detecting intra-abdominal extra-hepatic CRCR were, respectively, 85.7%, 85.7%, 88.9%, 88.9%, and 87.5% compared with 92.9%, 92.9%, 94.5%, 94.5%, and 93.8%, respectively, for PET/CT. The corresponding values for the detection of extra-abdominal and/or hepatic CRCR were 84.6%, 84.6%, 89.5%, 89.5%, and 87.5% for PET versus 100%, 92.3%, 95%, 100%, and 96.9% for PET/CT. For all forms of recurrence, the corresponding values for PET were 80%, 80%, 66.7%, 66.7%, and 75%, respectively, compared with 94.5%, 90%, 84.6%, 91.7%, and 90.6%, respectively, for PET/CT.

Conclusion

PET/CT enhances the accuracy and specificity of diagnosis of CRCRa. PET/CT grows to reach prominent roles for imaging and restaging of patients after colorectal carcinoma resection.     

Whole-body FDG-PET in patients with stage I non-seminomatous germ cell tumours

Relapse occurs in 30% of patients with stage I non-seminomatous germ cell tumours (NSGCT) within 1 year after orchiectomy. Whole-body positron emission tomography with fluorine-18 fluorodeoxyglucose (FDG-PET) may detect small metastases when standard staging with computed tomography (CT) and tumour markers is negative. In this study, 46 patients underwent FDG-PET after staging with normal CT and tumour markers. To exclude diagnostic test bias and workup bias, all patients had routine follow-up with repeated CT and tumour marker evaluation, even though the initial FDG-PET was positive. Thirty-six patients have remained disease free with a median follow-up of 48 months (range 24-76). Ten patients (22%) suffered disease relapse after a median of 2 months (range 1-8), and of these, seven had a true positive initial PET with increased uptake of FDG indicating metastatic disease. There were three false negative and no false positive PET scans. The sensitivity, specificity and accuracy of PET were 70%, 100% and 93%, respectively. The sensitivity of detecting small retroperitoneal metastases was 88%. The negative and positive predictive values were 92% and 100%, respectively, whereas the negative predictive value of standard staging procedures was 78%. FDG-PET thus seems to be superior to conventional staging (P=0.06) in stage I NSGCT. This non-invasive method may improve the overall management of patients with NSGCT.     

^18F-FDGPET／CT与超声造影在肝细胞癌复发判断中的对比研究

目的比较18F—FDGPET／CT与超声造影（CEUS）在HCC治疗后复发监测中的效能。方法回顾性分析27例HCC治疗后（15例部分切除术、12例射频消融）患者资料（男22例,女5例;平均年龄47岁）,患者治疗后均行18F．FDGPET／CT及CEUS监测肿瘤复发,2种检查间隔时间在2周内,间隔期间未接受任何治疗。依据病理或随访（〉6个月）结果,计算PET／CT与CEUS诊断HCC复发的灵敏度、特异性及准确性。比较CEUS与PET／CT对CEUS阳性患者和CEUS阴性患者的诊断效能。采用McNemar检验分析数据。结果27例治疗后HCC患者中,25例存在肝内复发,其中11例合并肝外转移;2例肝内未见复发,但有肝外转移。18F-FDGPET／CT及CEUS对肝内病灶检出的灵敏度分别为92．0％（23／25）和60．0％（15／25）,特异性均为2／2,准确性分别为92．6％（25／27）和63．0％（17／27）。15例CEUS阳性患者中,18F．FDGPET／CT及CEUS对肝内病灶检出的灵敏度及准确性均为100％（15／15）;12例CEUS阴性患者中,18F—FDGPET／CT及CEUS对肝内病灶检出的灵敏度分别为8／10和0,特异性均为2／2,准确性分别为83．3％（10／12）和16．7％（2／12）。18F-FDGPET／CT灵敏度及准确性明显高于CEUS,尤其是CEUS阴性组（x2=5．373和5．250,均P〈O．05）。18F-FDGPET／CT对肝外转移病灶的诊断灵敏度为100％（13／13）。结论18F—FDGPET／CT在评估HCC治疗后患者肝内肿瘤复发方面的灵敏度及准确性明显优于CEUS,并能有效发现肝外转移,可作为CEUS阴性而临床高度怀疑复发和转移的HCC患者的有效补充检查手段。     

18F-FDG PET/contrast enhanced CT in the standard surveillance of high risk colorectal cancer patients

ObjectiveTo assess the accuracy of FDG-PET/contrast enhanced CT (FDG-PET/ceCT) in the detection of unsuspected recurrence of colorectal cancer (CRC) in patients with high risk of relapse.MethodsThirty-three patients (14 females and 19 males, mean age: 62, range: 41–78), with CRC in complete remission, were prospectively included. All patients underwent FDG-PET/ceCT (58 studies).FDG-PET/ceCT was requested in the surveillance setting, and performed following a standardized protocol. A portal venous phase CT scan was performed after the injection of iodinated contrast agent.An individual and combined assessment of both techniques (PET and ceCT) was performed. Concordant and discordant findings of PET, ceCT and FDG-PET/ceCT were compared in a patient-based and a lesion-based analysis.The final diagnosis, recurrence or disease free status (DFS), were established by histopathology or clinical/radiological follow-up of at least 6 months.ResultsSeven out of 33 patients had a confirmed recurrence and the rest of patients had a DFS.In a patient-based analysis the sensitivity and specificity of PET, ceCT and PET/ceCT was of 86% and 88%, 86% and 92%, 86% and 85%, respectively.Attending to the lesion-based analysis, the sensitivity for PET, ceCT and PET/ceCT was of 56%, 71% and 97%, respectively.Both techniques showed a good concordance in the establishment of the final patient status. However, on a lesion-based analysis, no concordance was observed between them.ConclusionPET and ceCT seem to have similar value in the detection of unsuspected recurrence of CRC in a patient-based analysis. However, the combined assessment of PET/ceCT improves the accuracy in the lesion-based analysis.     

FDG-PET delayed imaging for the detection of head and neck cancer recurrence after radio-chemotherapy: comparison with MRI/CT

In advanced head and neck cancer, an organ-sparing approach comprising radiation therapy combined with intra-arterial chemotherapy has become an important technique. However, the high incidence of residual masses after therapy remains a problem. In this study, we prospectively evaluated the use of 2-[¹⁸F]fluoro-2-deoxy-d-glucose positron emission tomography (FDG-PET) delayed imaging for the detection of recurrence of head and neck cancer after radio-chemotherapy, and compared the FDG-PET results with those of magnetic resonance imaging (MRI) or computed tomography (CT). Forty-three lesions from 36 patients with head and neck cancer suspected to represent recurrence after radio-chemotherapy (median interval from therapy, 4 months) were studied. PET was performed at 2 h after FDG injection, and evaluated. The results were compared to those of contrast studies with MRI or CT performed within 2 weeks of the PET study, and to histological diagnosis (in all patients suspected of having recurrence) or clinical diagnosis. The lesion-based sensitivity (visual interpretation) and negative predictive value of FDG-PET (88% and 91%, respectively) were higher than those of MRI/CT (75% and 67% respectively). The specificity, accuracy and positive predictive value of FDG-PET (78%, 81% and 70%, respectively) were significantly (P<0.05) higher than those of MRI/CT (30%, 47% and 39% respectively). Three of six patients with false positive findings had post-therapy inflammation. Receiver operating characteristic (ROC) analysis showed that retrospective evaluation with the standardised uptake ratio yielded the best results (sensitivity 87.5%, specificity 81.5%), followed by visual interpretation and then the tumour/neck muscle ratio. An FDG-PET delayed imaging protocol yielded significantly better results for the detection of recurrence of head and neck cancer after radio-chemotherapy than MRI/CT. Because of the high negative predictive value of FDG-PET (91.3%), if PET is negative, further invasive procedures may be unnecessary.     

The impact of FDG-PET on the management algorithm for recurrent colorectal cancer.

Positron emission tomography (PET) has been successfully used to image colorectal cancer (CRC). This study evaluated the accuracy of 2-[(18)F]-fluoro-2-deoxy- D-glucose (FDG) PET for the detection and staging of recurrent CRC and the consequent impact on clinical management. Forty-two patients previously treated for CRC were investigated for suspected recurrence and, if recurrence was confirmed, the extent of disease was evaluated. All patients underwent whole-body FDG-PET and computed tomography (CT) scan and results were compared to assess sensitivity, specificity and diagnostic accuracy for each modality. We then assessed the FDG-PET directed alteration in clinical management from that planned on the basis of spiral CT results. FDG-PET was more sensitive (93%) than CT (73%) for detection of recurrence (specificity 58% and 75%, respectively). FDG-PET yielded a correct diagnosis in 35 (83%) out of 42 patients, while CT did so in 31 patients (74%). FDG-PET was more accurate than CT for staging local recurrence (sensitivity 100%, specificity 86% with FDG-PET vs 75% and 100%, respectively, with CT) and CRC liver metastases (sensitivity 100% vs 45%; specificity 100% for both). Overall, PET upstaged 8 out of 30 patients (27%) and altered patient management in 16 (38%) cases. This study confirms that FDG-PET is more sensitive than CT for the detection and staging of recurrent CRC. The results also indicate that FDG-PET is an accurate means of selecting appropriate patients for operative treatment. When applied to routine clinical practice, patient management is altered.     

Fluorine-18 fluorodeoxyglucose PET in the preoperative staging of colorectal cancer

Introduction In patients with colorectal cancer (CC), preoperative evaluation and staging should focus on techniques that might alter the preoperative or intraoperative surgical plan. Conventional imaging methods (CT, MRI) have low accuracy for identifying the depth of tumour infiltration and have limited ability to detect regional lymph node involvement. The aim of this study was to evaluate the utility of FDG-PET in the initial staging of patients with CC in comparison with conventional staging methods and to determine its impact on therapeutic management. Methods One hundred and four patients with a diagnosis of CC (53 males and 51 females; mean age 66.76 ± 12.36 years), selected prospectively, were studied for staging using a standard procedure (CT) and FDG-PET. When possible, the reference method was histology. Results In 14 patients, surgery was contraindicated by FDG-PET owing to the extent of disease (only 6/14 suspected by CT). FDG-PET revealed four synchronous tumours. For N staging, both procedures showed a relatively high specificity but a low diagnostic accuracy (PET 56%, CT 60%) and sensitivity (PET 21%, CT 25%). For M assessment, diagnostic accuracy was 92% for FDG-PET and 87% for CT. FDG-PET results led to modification of the therapy approach in 50% of patients with unresectable disease. FDG-PET findings were important, revealing unknown disease in 19.2%, changing the staging in 13.46% and modifying the scope of surgery in 11.54% (with a change in the therapeutic approach in 17.85% of those patients with rectal cancer). Conclusion Compared with conventional techniques, FDG-PET appears to be useful in pre-surgical staging of CC, revealing unsuspected disease and impacting on the treatment approach.     

Ovarian cancer recurrence: role of whole-body positron emission tomography using 2-[fluorine-18]-fluoro-2-deoxy-<Emphasis Type="SmallCaps">D</Emphasis>-glucose

This study was designed to assess the value of whole-body positron emission tomography (PET) using 2-[fluorine-18]-fluoro-2-deoxy- D-glucose (FDG) for the diagnosis of recurrent ovarian cancer. Twenty-five patients who had previously undergone surgery for ovarian cancer were imaged using whole-body FDG-PET. During the 4 weeks preceding the PET study, conventional imaging, comprising computed tomography (CT) and magnetic resonance (MR) imaging of the abdomen and/or pelvis, was performed and serum CA125 levels were measured. PET imaging was commenced at 60 min after the intravenous administration of FDG in all patients. PET results were compared with the results of conventional imaging and CA125 levels, and related to pathological findings and clinical follow-up for more than 6 months. FDG-PET showed a sensitivity of 80% (16/20), a specificity of 100% (5/5) and an accuracy of 84% accuracy (21/25) for the diagnosis of recurrent ovarian cancer. The sensitivity, specificity and accuracy of conventional imaging were 55% (11/20), 100% (5/5) and 64% (16/25), respectively. PET could detect recurrent lesions in seven of nine patients in whom conventional imaging was falsely normal, while conventional imaging was true positive in two of four patients with false-negative PET results. The CA125 results showed a sensitivity of 75% (15/20), a specificity of 100% (5/5) and an accuracy of 80% accuracy (20/25). Among the 15 patients with true-positive CA125 results, PET correctly detected abnormal foci of recurrence in 13 patients (86.7%) whereas conventional imaging showed recurrent lesions in only eight patients (53.3%). In conclusion, our preliminary study demonstrates that FDG-PET may be accurate and useful for the detection of tumour recurrence when conventional imaging is inconclusive or negative, especially in patients with abnormal CA125 levels.     

Diagnostic Accuracy of F-18 FDG-PET in the Assessment of Posttherapeutic Recurrence of Head and Neck Cancer

The purpose of this study was to compare whole-body fluorine-18-fluorodeoxyglucose positron emission tomography (F-18 FDG-PET) with conventional imaging modalities (CI: CT/MRI) in the detection of recurrent head and neck cancer. Whole-body F-18 FDG-PET was performed in 45 patients (recurrence = 39; no recurrence = 16) with previous head and neck cancer. We compared detectability by the period from initial cancer treatment and treatment modalities. Thirty were PET-positive and 15 were PET-negative. The sensitivity, specificity, and accuracy of PET were 97%, 88%, and 93%, respectively (corresponding figures of CI were 73%, 85%, and 77%). In 18 patients who underwent PET less than 3 months after the completion of cancer treatment, the sensitivity, specificity, and accuracy were 100%, 86%, and 94%, while for CI, the corresponding figures were 67%, 71%, and 69%. In 18 patients who had undergone surgery, PET results were 14 true positive and 4 were true negative; significantly higher detectability than CI. Among the patients who were evaluated for more than 6 months or treated by radiotherapy without surgery, diagnostic accuracy was almost the same. Whole body F-18 FDG-PET was a valuable tool in the evaluation of post-therapeutic recurrence of head and neck cancer.     

Radiological staging in patients with hilar cholangiocarcinoma: a systematic review and meta-analysis

Objective To obtain diagnostic performance values of CT, MRI, ultrasound and 18-fludeoxyglucose positron emission tomography (PET)/CT for staging of hilar cholangiocarcinoma. Methods A comprehensive systematic search was performed for articles published up to March 2011 that fulfilled the inclusion criteria. Study quality was assessed with the quality assessment of diagnostic accuracy studies tool. Results 16 articles (448 patients) were included that evaluated CT (n=11), MRI (n=3), ultrasound (n=3), or PET/CT (n=1). Overall, their quality was moderate. The accuracy estimates for evaluation of CT for ductal extent of the tumour was 86%. The sensitivity and specificity estimates of CT were 89% and 92% for evaluation of portal vein involvement, 83% and 93% for hepatic artery involvement, and 61% and 88% for lymph node involvement, respectively. Data were too limited for adequate comparisons of the different techniques. Conclusion Diagnostic accuracy studies of CT, MRI, ultrasound or PET/CT for staging of hilar cholangiocarcinoma are sparse and have moderate methodological quality. Data primarily concern CT, which has an acceptable accuracy for assessment of ductal extent, portal vein and hepatic artery involvement, but low sensitivity for nodal status.