The role of FDG-PET/CT in the detection of recurrent colorectal cancer

Purpose The conventional diagnostic techniques used to assess recurrence of colorectal cancer (CRCR) often yield unspecific findings. Integrated FDG-PET/CT seems to offer promise for the differential diagnosis of benign and malignant lesions. The aim of this study was to compare the value of FDG-PET and PET/CT in the detection of CRCR subsequent to colonic resection or rectal amputation. Methods The population for this retrospective study comprised 84 patients with suspected CRCR. The sensitivity, specificity and accuracy of PET and PET/CT were calculated for (a) intra-abdominal extrahepatic recurrences, (b) extra-abdominal and/or hepatic recurrences and (c) all recurrences, and tumour marker levels were analysed. Results The sensitivity, specificity and overall accuracy of PET in detecting intra-abdominal extrahepatic CRCR were 82%, 88% and 86%, respectively, compared with 88%, 94% and 92%, respectively, for PET/CT. The corresponding figures for detection of extra-abdominal and/or hepatic CRCR were 74%, 88% and 85% for PET and 95%, 100% and 99% for PET/CT. Considering the entire population, the sensitivity, specificity and overall accuracy of PET were 80%, 69% and 75%, respectively, compared with 89%, 92% and 90%, respectively, for PET/CT. FDG-PET/CT examination correctly detected 40 out of a total of 45 patients with CRCR. Two of five patients with falsely negative FDG-PET/CT findings had local microscopic recurrences and one had miliary liver metastases. Of 39 patients without CRCR, three showed false positive FDG-PET/CT results. Two of these cases were due to increased accumulation in inflammatory foci in the bowel wall, while one was due to haemorrhaging into the adrenal gland. Conclusion FDG-PET/CT appears to be a very promising method for distinguishing a viable tumour from fibrous changes, thereby avoiding unnecessary laparotomy.     

Importance of CT and MRI in the follow-up of patients with rectal cancer

INDICATION: Presentation and evaluation of diagnostic procedures for the follow-up in patients with suspected local recurrence of rectal cancer. METHODS: Follow-up usually is performed using endoscopy and endosonography. Imaging techniques applied are also contrast enema as well as helical CT,MR imaging (MRI), and positron emission tomography (PET). RESULTS: The results demonstrate the difficulty of all available modalities to differentiate between early tumor recurrences from post-therapeutic alterations.Especially the differentiation of scar tissue and local tumor recurrence, the detection of lymph node as well as pulmonary or hepatic metastasis requires a large diagnostic effort with employment of various imaging modalities.Values determined for sensitivity and specificity for CT are 84% and 91% with a positive predictive value (PPV) of 78%.For MRI and PET the sensitivity are 94% and 98%,and the specificity 92% and 90% with a PPV of 93% for the PET. CONCLUSION: The results demonstrate the increasing importance of CT and MRI in the follow-up of patients with rectal cancer and enable an accurate and early diagnosis through employment of new examination strategies and sequence protocols.PET remains an add-on examination in uncertain local lesions.     

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.     

The utility of FDG-PET/CT as an effective tool for detecting recurrent colorectal cancer regardless of serum CEA levels

Purpose

Tumor recurrence of colorectal cancers (CRC) is generally followed up by analyses of the serum carcinoembryonic antigen (CEA) levels. However, recent evidence suggests that tumor recurrence can also be visualized by 18F-fluoro-deoxyglucose emission tomography/computed tomography (FDG-PET/CT) in patients with normal CEA levels. We retrospectively evaluated the diagnostic performance of FDG-PET/CT in patients with suspected recurrence of CRC by comparing PET/CT performance in patients with normal CEA levels with PET/CT performance in patients with elevated CEA levels.

Methods

A total of 235 patients with CRC who had been treated with surgery and/or chemotherapy/radiotherapy underwent PET/CT for the detection of tumor recurrence. The patients [96 females and 139 males; age (mean?±?SD) 59.9?±?12.6?years; range 18?C85] were divided into 2 groups based on whether their CEA levels were normal (<5?ng/ml) (Group 1, n?=?118) or elevated (>5?ng/ml) (Group 2, n?=?117). All of the patients had suspected recurrence based on raised CEA levels, clinical symptoms, and/or tumor detection using other imaging modalities.

Results

Of the 235 patients, 172 (73.1?%) had disease recurrence confirmed by a pathological examination (either biopsy or surgical exploration) or clinical follow-up studies. The FDG-PET/CT study yielded a true positive in detecting recurrence in 169 (71.9?%) patients, a true negative in 53 (22.5?%) patients, a false negative in 3 (1.2?%) patients and a false positive in 10 (4.2?%) patients. CRC recurrence was detected in 64.4?% (76/118) and 88?% (103/117) patients in Group 1 and Group 2 with FDG-PET/CT, respectively. The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy of the FDG-PET/CT study for establishing recurrence were 100, 84, 89.4, 100 and 93.2?%, respectively, for Group 1; by contrast, these parameters were 97.1, 84.6, 98, 78.5 and 95.7?%, respectively, for Group 2. The number of patients with hepatic and extra-hepatic metastases, such as lung and abdominal lymph node metastasis, detected with FDG-PET/CT was significantly different in Group 1 than in Group 2; however, the number of patients with local recurrence and peritoneal implants detected with FDG-PET/CT was not different between the two groups.

Conclusions

FDG-PET/CT can accurately detect tumor recurrence in patients with suspected recurrent CRC, even for patients with normal CEA levels.     

Dual-modality FDG-PET/CT in follow-up of patients with recurrent iodine-negative differentiated thyroid cancer

The usefulness of combined 2-[¹⁸F] fluoro-2-deoxy-D-glucose positron emission tomography and computed tomography (FDG-PET/CT) in locating suspected recurrence in patients with iodine-negative differentiated thyroid cancer (DTC) was evaluated. Thirty-six patients with DTC and suspected iodine-negative recurrence underwent restaging with FDG-PET/CT. The images of CT, FDG-PET, both modalities viewed side by side (CT+PET), and FDG-PET/CT were evaluated by two physicians separately. Imaging results were correlated with either histology (n = 20) and/or clinical follow-up of at least 36 months. Recurrent disease was diagnosed in 22/36 patients. FDG-PET alone, CT alone, CT+PET, and FDG-PET/CT showed a sensitivity of 82%, 73%, 91%, and 96%, respectively. Specificities were 79%, 71%, 79%, and 100%, respectively. FDG-PET/CT significantly improved specificity compared with CT+PET and resulted in a further treatment modification in 5/36 patients (14%). CT alone was especially sensitive for lung metastases, FDG-PET alone for the remainder of the body. Accurate fusion of functional and morphologic data by FDG-PET/CT improves the staging accuracy of patients with suspected recurrence of iodine-negative DTC. This has an impact on patient management in a substantial number of patients.     

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.     

Impact of [<Superscript>18</Superscript>F]FDG-PET on the primary staging of small-cell lung cancer

Purpose The purpose of this study was to evaluate the impact of [¹⁸F]fluorodeoxy-d-glucose positron emission tomography (FDG-PET) on the primary staging of patients with small-cell lung cancer (SCLC).Methods FDG-PET was performed in 120 consecutive patients with SCLC during primary staging. In addition, brain examinations with both FDG-PET and cranial magnetic resonance imaging (MRI) or computed tomography (CT) were performed in 91 patients. Results of FDG-PET were compared with those of conventional staging procedures. FDG-PET detected markedly increased FDG uptake in the primary tumours of all 120 patients (sensitivity 100%).Results Complete agreement between FDG-PET results and other staging procedures was observed in 75 patients. Differences occurred in 45 patients at 65 sites. In 47 sites the FDG-PET results were proven to be correct, and in ten, incorrect. In the remaining eight sites, the discrepancies could not be clarified. In 14/120 patients, FDG-PET caused a stage migration, correctly upstaging ten patients to extensive disease and downstaging three patients by not confirming metastases of the adrenal glands suspected on the basis of CT. Only 1/120 patients was incorrectly staged by FDG-PET, owing to failure to detect brain metastases. In all cases the stage migration led to a significant change in the treatment protocol. Sensitivity of FDG-PET was significantly superior to that of CT in the detection of extrathoracic lymph node involvement (100% vs 70%, specificity 98% vs 94%) and distant metastases except to the brain (98% vs 83%, specificity 92% vs 79%). However, FDG-PET was significantly less sensitive than cranial MRI/CT in the detection of brain metastases (46% vs 100%, specificity 97% vs 100%).Conclusion The introduction of FDG-PET in the diagnostic evaluation of SCLC will improve the staging results and affect patient management, and may reduce the number of tests and invasive procedures.     

Combined FDG-PET/CT for the detection of unknown primary tumors: systematic review and meta-analysis

The aim of this study was to systematically review and meta-analyze published data on the diagnostic performance of combined 18F-fluoro-2-deoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) in the detection of primary tumors in patients with cancer of unknown primary (CUP). A systematic search for relevant studies was performed of the PubMed/MEDLINE and Embase databases. Methodological quality of the included studies was assessed. Reported detection rates, sensitivities and specificities were meta-analyzed. Subgroup analyses were performed if results of individual studies were heterogeneous. The 11 included studies, comprising a total sample size of 433 patients with CUP, had moderate methodological quality. Overall primary tumor detection rate, pooled sensitivity and specificity of FDG-PET/CT were 37%, 84% (95% CI 78–88%) and 84% (95% CI 78–89%), respectively. Sensitivity was heterogeneous across studies (P = 0.0001), whereas specificity was homogeneous across studies (P = 0.2114). Completeness of diagnostic workup before FDG-PET/CT, location of metastases of unknown primary, administration of CT contrast agents, type of FDG-PET/CT images evaluated and way of FDG-PET/CT review did not significantly influence diagnostic performance. In conclusion, FDG-PET/CT can be a useful method for unknown primary tumor detection. Future studies are required to prove the assumed advantage of FDG-PET/CT over FDG-PET alone and to further explore causes of heterogeneity.     

Preoperative staging of biliary carcinoma using 18F-fluorodeoxyglucose PET: prospective comparison with PET+CT, MDCT and histopathology

The aim of this study was to evaluate the value of positron emission tomography with ¹⁸F-labeled fluorodeoxyglucose (FDG-PET) as a preoperative diagnostic investigation in patients with biliary carcinoma. Seventy-two patients with potentially resectable biliary carcinoma underwent preoperative multidetector-row computed tomography (MDCT) and FDG-PET. Both diagnoses were compared with subsequent histopathology and follow-up results. In 64 lesions with biliary carcinoma, 57 (89%) revealed an intense focal accumulation on FDG-PET and were interpreted as malignant. On the other hand, eight benign lesions did not show any specific accumulation. Detection rate of FDG-PET in the nodular type of the tumour (96% or 27/28) was superior to that of the infiltrating type (74% or 17/23) (p = 0.037). For the evaluation of lymph node metastasis, the overall accuracy was 69% (35/51) in both FDG-PET and MDCT: FDG-PET had a lower sensitivity (33% vs. 57%) and a higher specificity (97% vs. 79%) than MDCT, although the values were not significantly different. FDG-PET revealed all six lesions of distant metastases in six patients including two lesions missed by MDCT. FDG-PET has high detectability of biliary malignancies. Like MDCT, FDG-PET offers only modest accuracy for regional lymph node staging, but it may reveal distant metastases missed by MDCT.     

Role of [18F]FDG-PET/CT after radiofrequency ablation of liver metastases: preliminary results

PURPOSE: Focal metastasis may be treated with radiofrequency ablation (RFA), a low invasive method yet limited by the lack of direct evidence of radicality of treatment. We, hereby, aimed at assessing the role of positron emission tomography-computed tomography (PET/CT) with fluoride radiolabeled deoxy-glucose ([(18)F]FDG) in RFA treatment success evaluation and early diagnosis of local relapse of liver metastasis after RFA procedure. METHODS: RFA was performed in nine patients on 12 liver metastasis, serially imaged through [(18)F]FDG-PET/CT and multidetector CT (MDCT) at 1, 3, 6, and 9 months after treatment. Eight lesions were also scanned with [(18)F]FDG-PET/CT at 1 week after treatment. Imaging analyses were performed on 47 [(18)F]FDG-PET/CT and 51 MDCT. Imaging reading outcomes were compared to each other and to biopsy tissue results when available. RESULTS: In one case, [(18)F]FDG-PET/CT revealed radiotracer uptake at RFA site a week after procedure. Negative concordant outcome was obtained on eight lesions at 1 month after RFA, on eight cases at 3 months, on four at 6 months, and on two cases at 9 months. Extra-liver (peritoneal) disease was detected in one case by both [(18)F]FDG-PET/CT and MDCT. In seven cases, [(18)F]FDG-PET/CT revealed the presence of local recurrence earlier than MDCT. In no cases did MDCT detect local relapse earlier than [(18)F]FDG-PET/CT. CONCLUSION: [(18)F]FDG-PET/CT may detect RFA treatment failure as well as local relapse after RFA earlier than MDCT.     

Current clinical use of 18FDG-PET/CT in patients with thoracic and systemic sarcoidosis

Purpose

This study assessed the role of whole-body ¹⁸fluorodeoxyglucose positron-emission tomography/computed tomography (¹⁸FDG PET/CT) in the restaging and follow-up of patients with sarcoidosis previously studied by multidetector computed tomography (MDCT).

Materials and methods

This retrospective study enroled 21 patients to evaluate the sensitivity, specificity and accuracy of ¹⁸FDG-PET/CT and MDCT. The results of the two techniques were compared with the Mc Nemar test. Cohen’s K was used to compare concordance at the different lesion sites.

Results

The sensitivity, specificity and accuracy of ¹⁸FDG-PET/CT were 80, 66.67, and 76.19 %, respectively. The sensitivity, specificity and accuracy of MDCT were 93.33, 33.33, and 76.19 %, respectively. In 16 patients who underwent whole-body MDCT, the sensitivity, specificity and accuracy values were 91.67, 81.25, and 50 % (MDCT) and 100, 50, and 87.5 % (¹⁸FDG-PET/CT).

Conclusions

¹⁸FDG-PET/CT is useful in evaluating the extent of sarcoidosis and recognising lesions at different sites, including lymph nodes, lungs, liver, spleen and bone. It also improves the interpretation of the morphological lesions seen on MDCT and depicts a larger number of lesions. Therefore, ¹⁸FDG-PET/CT could be used to complement other more traditional techniques for the restaging and follow-up in patients with sarcoidosis.     

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.     

Stellenwert der PET/CT zur Bildgebung des kolorektalen Karzinoms

CLINICAL/METHODICAL ISSUE: Fluorodeoxyglucose-positron emission tomography/computed tomography (FDG-PET/CT) has emerged as a very useful imaging modality in the management of colorectal carcinoma. Data from the literature regarding the role of PET/CT in the initial diagnosis, staging, radiotherapy planning, response monitoring and surveillance of colorectal carcinoma is presented. Future directions and economic aspects are discussed. STANDARD RADIOLOGICAL METHODS: Computed tomography (CT), magnetic resonance imaging (MRI) and FDG-PET for colorectal cancer and endorectal ultrasound for rectal cancer. METHODICAL INNOVATIONS: Combined FDG-PET/CT. PERFORMANCE: While other imaging modalities allow superior visualization of the extent and invasion depth of the primary tumor, PET/CT is most sensitive for the detection of distant metastases of colorectal cancer. ACHIEVEMENTS: We recommend a targeted use of PET/CT in cases of unclear M staging, prior to metastasectomy and in suspected cases of residual or recurrent colorectal carcinoma with equivocal conventional imaging. The role of PET/CT in radiotherapy planning and response monitoring needs to be determined. Currently there is no evidence to support the routine use of PET/CT for colorectal screening, staging or surveillance. PRACTICAL RECOMMENDATIONS: To optimally exploit the synergy between morphologic and functional information, FDG-PET should generally be performed as an integrated FDG-PET/CT with a contrast-enhanced CT component in colorectal carcinoma.     

^18FDG-PET和^99mTc-MDP骨扫描检测骨转移瘤价值的比较

目的:评价18FDG-PET恶性肿瘤骨转移的作用及与99mTc-MDP-ECT 比较.材料和方法: 经病理证实为恶性肿瘤患者51 例及非肿瘤性疾病5例在本科同时接受18F-FDG-PET和99mTc-MDP-ECT检查(时间间隔不超过2周).骨转移的诊断由病理、X线或CT/MRI、随访超过1年综合决定.结果:99mTc-MDP和18FDG-PET 对骨转移瘤诊断的灵敏度、特异性、准确率率分别为93.7%、93.7%,97.5%、50%,90.8%、62.5%.99mTc-MDP和18FDG-PET均为阳性15例,其中证实骨转移为14例,假阳性1例;均为阴性例数为20例.21例不相符的结果中20例99mTc-MDP-ECT 阳性而18F-FDG-PET 为阴性.18F-FDG-PET和99mTc-MDP-ECT假阴性各1例.均诊断为多发骨转移的12例患者中99mTc-MDP-ECT发现的骨转移病灶数多于18F-FDG-PET.结论:18F-FDG-PET 与99mTc-MDP骨扫描相比较对肿瘤骨转移的探测有较高的特异性,但敏感性较低.     

Detection of recurrence in patients with rectal cancer: PET/CT after abdominoperineal or anterior resection

PURPOSE: To assess diagnostic accuracy of combined positron emission tomography (PET) and computed tomography (CT) in detection of pelvic recurrence in patients with rectal cancer who underwent abdominoperineal or anterior resection. MATERIALS AND METHODS: Sixty-two patients were enrolled; 37 were men, and 25 were women. Seventeen patients underwent abdominoperineal resection and 45 underwent anterior resection with an anastomosis in the pelvic region before referral for PET/CT. Pelvic sites of fluorine 18 ((18)F) fluorodeoxyglucose (FDG) uptake were rated separately on PET and PET/CT images as benign or malignant on the basis of shape, location, and intensity of (18)F FDG uptake (1-2 = benign and/or physiologic, 3 = equivocal, 4-5 = malignant). Two readers interpreted images in consensus. Altered pelvic anatomy and presence of presacral abnormalities were assessed with CT. Pelvic recurrence was confirmed with histologic analysis or clinical and imaging follow-up. Sensitivity, specificity, positive and negative predictive values, and accuracy of PET and PET/CT in the detection of pelvic recurrence were compared with lesion- and patient-based analyses by using the chi(2) test. Clinical relevance of PET/CT assessment was determined. RESULTS: Of 81 pelvic sites with increased (18)F FDG uptake, 44 were malignant. Sensitivity, specificity, positive predictive value, negative predictive value, and accuracy for differentiating malignant from benign (18)F FDG uptake in the pelvis were 98%, 96%, 90%, 97%, and 93% for PET/CT and 82%, 65%, 73%, 75%, and 74% for PET, respectively. The most common cause for false-positive interpretation of PET findings was physiologic (18)F FDG uptake in displaced pelvic organs. Presacral CT abnormalities were present in 30 (48%) of 62 patients, and seven (23%) abnormalities were malignant. PET/CT was used to distinguish benign and malignant presacral abnormalities with a sensitivity, specificity, positive predictive value, and negative predictive value of 100%, 96%, 88%, and 100%, respectively. PET/CT findings were clinically relevant in 29 (47%) of 62 patients. CONCLUSION: PET/CT is an accurate technique in the detection of pelvic recurrence after surgical removal of rectal cancer.     

Roles of positron emission tomography with fluorine-18-deoxyglucose in the detection of local recurrent and distant metastatic sarcoma

Sarcomas are a heterogeneous group of tumors comprising approximately 1% of all malignancies. Definitive treatment of sarcoma is surgical resection. However, after surgical removal, 40% to 60% of the patients will develop local or distant recurrence. Therefore, the early detection and treatment of recurrence is an important part of modern sarcoma therapy. Positron emission tomography with fluorine-18-deoxyglucose (FDG-PET) has been highly successful in detecting and staging a variety of malignancies. However, its use in the management of patients with sarcoma is less defined. The purpose of our study was to assess the potential roles of FDG-PET in the detection of local recurrence and distant metastases. In this retrospective study, the images of 33 FDG-PET scans, reports of 29 computed tomography (CT) scans, and 8 magnetic resonance imaging (MRI) scans from 28 patients were compared with surgical pathology or clinical follow up for at least 6 months. FDG-PET detected all 25 cases of local and distant recurrences with 100% sensitivity. CT was able to detect 18 of the 22 possible cases of recurrent disease, whereas MRI was able to detect 5 of 7 cases of recurrent disease. PET was particularly useful in patients with extensive histories of surgery and radiation therapy, precisely the setting in which CT and MRI have the lowest specificity and sensitivity. In conclusion, FDG-PET was a sensitive test to detect local and distant recurrences of sarcoma and this warrants further investigation.     

The clinical utility of FDG-PET/CT in follow up and restaging of breast cancer patients

Background

Early diagnosis and accurate staging of loco-regional and distant recurrence after treatment of breast cancer is decisive for further therapeutic planning. Our aim was to evaluate the role of FDG-PET/CT in the follow up and restaging of breast cancer patients.

Methods

We retrospectively evaluated 34 female patients with a history of breast cancer. Patients were referred for a PET/CT scan because of suspected recurrence (n = 15), whole body staging in already confirmed cases of recurrence (n = 5), follow up and reassurance in asymptomatic patients (n = 7), follow up after local ablative therapy of liver metastases (n = 5), follow up after treatment of bone metastases (n = 2). PET-CT findings were compared with the findings obtained by other imaging modalities, histopathology, together with clinical and imaging follow up for at least 6 months.

Results

The PET/CT was considered pathological in 21/34 patients. Incorrect interpretations of PET/CT images occurred in 3 patients (8.8%). PET/CT showed an overall diagnostic accuracy of 91.2% with a sensitivity of 90.5% and a specificity of 92.3%. The PPV and NPV were 95% and 85.7%, respectively.

Conclusion

FDG-PET/CT may play a substantial role in the restaging and follow up of patients with breast cancer showing high sensitivity and specificity.     

67Ga whole-body scintigraphy in the evaluation of head and neck squamous cell carcinoma.

The diagnostic accuracy of 67Ga-citrate whole-body scintigraphy for the evaluation of primary tumours, local recurrences, cervical node metastases and distant metastases was investigated in patients with head and neck squamous cell carcinoma (SCC). Altogether, 102 67Ga-citrate whole-body scans were performed on 83 patients with head and neck SCC using a dual-headed gamma camera. The results were compared with those of computed tomography (CT) and final diagnosis. 67Ga scintigraphy correctly diagnosed 28 of 29 primary lesions, a sensitivity of 97% (CT = 97%). For tumour recurrence, 67Ga scintigraphy correctly diagnosed 13 of 15 recurrences and 53 of 58 instances of no recurrence, giving a sensitivity of 87% and a specificity of 91% (CT = 80 and 62%, respectively). Scintigraphy correctly diagnosed 23 of 31 metastatic sides of the neck and all 173 negative sides of the neck, giving a sensitivity of 74% and a specificity of 100% (CT = 90 and 84%, respectively). Finally, scintigraphy correctly diagnosed all 12 distant metastases as well as 86 of 90 cases of no metastasis, resulting in a sensitivity of 100% and a specificity of 96%. Furthermore, in five patients, distant metastases were initially detected on 67Ga scintigraphy. In conclusion, 67Ga whole-body scintigraphy with a dual-headed camera resulted in a high sensitivity and specificity for the detection of primary lesions, recurrences and distant metastases of head and neck SCC. Although the sensitivity for detecting neck node metastases was relatively low, the specificity was high. Thus, 67Ga scintigraphy is an effective technique for the evaluation of head and neck SCC, especially tumour recurrence and distant metastases.     

Combined metabolic and morphologic imaging in thyroid carcinoma patients with elevated serum thyroglobulin and negative cervical ultrasonography: role of <Superscript>124</Superscript>I-PET/CT and FDG-PET

Purpose This study sought to compare iodine-124 positron emission tomography/computed tomography (¹²⁴I-PET/CT) and 2-[¹⁸F]fluoro-2-deoxy-d-glucose- (FDG-) PET in the detection of recurrent differentiated thyroid carcinoma (DTC) lesions in patients with increasing serum thyroglobulin (Tg), Tg-antibodies, or both, but without pathological cervical ultrasonography. We assessed the lesion detection accuracy of ¹²⁴I-PET alone, CT alone, ¹²⁴I-PET/CT, FDG-PET, and all these modalities combined. Material and methods The study included 21 patients (9 follicular, 12 papillary DTC) who had been rendered disease-free by thyroidectomy and radioiodine treatment (RIT) and followed up for 21–275 months after the last RIT. In all patients, FDG-PET was performed first. Within 1 week, ¹²⁴I-PET/CT was performed 24 h after oral administration of 43 ± 11 MBq ¹²⁴I. Imaging results were correlated with further clinical follow-up with (n = 12) or without (n = 9) post-study histology as the reference standard. Results The sensitivities for DTC lesion detection were: ¹²⁴I-PET, 49%; CT, 67%; ¹²⁴I-PET/CT, 80%; FDG-PET, 70%; and all modalities combined, 91%. For local recurrences (distant metastases), the sensitivities were: ¹²⁴I-PET, 60% (45%); CT, 20% (84%); and FDG-PET, 65% (71%). One-third of lesions demonstrated pathological tracer uptake with both ¹²⁴I- and FDG-PET, while two-thirds were positive with only one of these modalities. Conclusion Used together, ¹²⁴I-PET and CT allow localization of foci of highly specific ¹²⁴I uptake as well as non-iodine-avid lesions. The combination of ¹²⁴I-PET/CT and FDG-PET improves restaging in recurrent DTC by enabling detection on whole-body scans of local recurrence or metastases that are often not found if only one of the methods or other imaging modalities are applied.     

The impact of <Superscript>18</Superscript>F-FDG PET/CT in patients with liver metastases

Purpose The aim of this study was to assess the performance of ¹⁸F-fluorodeoxyglucose positron emission tomography/computed tomography (¹⁸F-FDG PET/CT) versus dedicated contrast-enhanced CT (CECT) in the detection of metastatic liver disease. Methods All patients that presented to our Institution with suspected metastatic liver disease who underwent ¹⁸F-FDG PET/CT and CECT within 6 weeks of each other, were retrospectively analyzed, covering a 5-year period. One hundred and thirty-one patients (67 men, 64 women; mean age 62) were identified. Seventy-five had colorectal carcinoma and 56 had other malignancies. The performance of CECT and that of ¹⁸F-FDG-PET/CT in detecting liver metastases were compared. The ability of each to detect local recurrence, extrahepatic metastases and to alter patient management was recorded. The final diagnosis was based on histology, clinical and radiological follow-up (mean 23 months). Results In detecting hepatic metastases, ¹⁸F-FDG-PET/CT yielded 96% sensitivity and 75% specificity, whilst CECT showed 88% sensitivity and 25% specificity. ¹⁸F-FDG-PET/CT and CECT were concordant in 102 out of 131 patients (78%). In the colorectal group ¹⁸F-FDG-PET/CT showed 94% sensitivity and 75% specificity, whilst CECT had 91% sensitivity and 25% specificity. In the noncolorectal group ¹⁸F-FDG-PET/CT showed 98% sensitivity and 75% specificity whilst CECT had 85% sensitivity and 25% specificity. Overall, ¹⁸F-FDG-PET/CT altered patient management over CECT in 25% of patients. CECT did not alter patient management over ¹⁸F-FDG-PET/CT alone in any patients. Conclusion ¹⁸F-FDG-PET/CT performed better in detecting metastatic liver disease than CECT in both colorectal and noncolorectal malignancies, and frequently altered patient management. The future role of CECT in these patients may need to be re-evaluated to avoid potentially unnecessary duplication of investigation where ¹⁸F-PET/CT is readily available. Authors stated no financial relationship to disclose