Detection of aortic graft infection by 18-fluorodeoxyglucose positron emission tomography combined with computed tomography

Functional in vivo molecular imaging is provided with 18-fluorodeoxyglucose positron emission tomography (FDG-PET), which can detect cells with high glucose turnover. FDG-PET is an established imaging tool in oncology but has also been used in infectious and inflammatory diseases. PET combined with computed tomography (PET/CT) shows the metabolic activity with precise anatomic localization. More than 2000 scanners have now been installed worldwide, and with better availability, this hybrid method has the potential to become an important imaging tool in the management of suspected aortic graft infections, especially in patients with low-grade graft infection. We report a patient with a suspected aortic graft infection that was confirmed and anatomically localized by FDG-PET/CT. An extra-anatomic bypass and extirpation of the aortic graft was performed. The perioperative location of the graft infection coincided exactly with the place of FDG uptake shown on PET/CT. The patient had an uneventful postoperative recovery and did well during 6 months of follow-up.     

Accuracy of FDG-PET–CT in the Diagnostic Work-up of Vascular Prosthetic Graft Infection

ObjectivesTo investigate the diagnostic accuracy of fluoro-2-deoxy-d-glucose positron emission tomography (FDG-PET) compared with computed tomography (CT) scanning and added value of fused FDG-PET–CT in diagnosing vascular prosthetic graft infection.DesignProspective cohort study with retrospective analysis.MaterialsTwenty five patients with clinically suspected vascular prosthetic infection underwent CT and FDG-PET scanning.MethodsTwo nuclear medicine physicians assessed the FDG-PET scans; all CT scans were assessed by two radiologists. Fused FDG-PET/CT were judged by the radiologist and the nuclear medicine physician. The concordance between CT and FDG-PET and the inter-observer agreement between the different readers were investigated.ResultsFifteen patients had a proven infection by culture. Single FDG-PET had the best results (sensitivity 93%, specificity 70%, positive predictive value 82% and negative predictive value 88%). For CT, these values were 56%, 57%, 60% and 58%, respectively. Fused CT and FDG-PET imaging also showed high sensitivity and specificity rates and high positive and negative values. Inter-observer agreement for FDG-PET analysis was excellent (kappa = 1.00) and moderate for CT and fused FDG-PET–CT analysis (0.63 and 0.66, respectively).ConclusionFDG-PET scanning showed a better diagnostic accuracy than CT for the detection of vascular prosthetic infection. This study suggests that FDG-PET provides a useful tool in the work-up for diagnosis of vascular prosthetic graft infection.     

18-fluorodeoxyglucose positron emission tomography as a novel imaging tool for the diagnosis of aortoenteric fistula and aortic graft infection--a case report

The diagnosis of aortic graft infection and aortoenteric fistula can be difficult to establish using conventional radiographic imaging modalities. Positron emission tomography (PET) imaging with 18-fluorodeoxyglucose (FDG) can rapidly provide anatomically clear images and define areas of inflammation with increased glucose metabolism. In this report the authors present a case of aortoenteric fistula diagnosed by FDG-PET. Early diagnosis led to rapid surgical intervention with graft removal and extraanatomic bypass. These encouraging results warrant larger controlled studies to evaluate the utility of FDG-PET in the diagnosis of prosthetic aortic graft infection.     

Diagnosis of vascular prosthesis infection with FDG-PET/CT

Fluorodeoxyglucose positron emission tomography (FDG-PET) is on the verge of becoming an established imaging tool in the fields of clinical oncology, cardiology, and neurology. Because of the high glucose uptake of inflammatory cells, FDG scanning is an appropriate tool for use in tracing suspected inflammation or to evaluate infection. PET, although highly sensitive, often lacks the ability to define the precise anatomic location of abnormal FDG accumulation. The new PET/computed tomography (CT) technology provides precise registration of metabolic and structural imaging data in a single session. We report positive FDG-PET/CT findings in an infected vascular prosthesis 6 months after grafting. Our experience and a few available case reports support the hypothesis that FDG-PET/CT may have a promising role in future noninvasive diagnosis of infected vascular grafts.     

Clinical usefulness of FDG-PET/CT scan imaging in the management of posttransplant lymphoproliferative disease

BACKGROUND: Posttransplant lymphoproliferative disease (PTLD) is, aside skin cancer, the most common malignancy occurring after solid organ transplant in adults. Fluorodeoxyglucose (FDG) positron emission tomography (PET) has proved useful in the management of lymphomas. METHODS: We report our experience with the use of FDG-PET inline with computed tomography (CT) scanning in the management of four transplant recipients with histologically confirmed PTLD, including three monomorphic PTLDs and one polymorphic PTLD. RESULTS: FDG-PET/CT scan at diagnosis showed increased FDG uptake in all examined PTLD lesions, and the disease was upstaged on the basis of FDG-PET/CT scan results over conventional CT scanning in one patient. At the end of treatment, PET/CT scans no longer demonstrated FDG uptake in the original PTLD lesions in all patients. Complete remission of disease persisted for at least 1 year after diagnosis in all. CONCLUSIONS: Our results strongly support that FDG-PET scanning is highly specific for diagnosis and follow-up of PTLD. The clinical relevance of including FDG-PET/CT scanning in the management of PTLD should be evaluated in a larger prospective cohort study.     

Clinical role of F-18 fluorodeoxyglucose positron emission tomography for detection and management of renal cell carcinoma

PURPOSE: We evaluate the accuracy of F-18 fluorodeoxyglucose (FDG)-positron emission tomography (PET) for staging and management of renal cell carcinoma. MATERIALS AND METHODS: FDG-PET was performed in 25 patients with known or suspected primary renal tumors and/or metastatic disease and compared with conventional imaging techniques, including computerized tomography (CT). Histopathological confirmation was obtained in 18 patients and confirmation of the disease was by followup in the remainder. The impact of FDG-PET on disease management was also assessed. RESULTS: Of the 17 patients with known or suspected primary tumors FDG-PET was true positive in 15, true negative in 1 and false-negative in 1. Comparative CT was true positive in 16 patients and false-positive in 1. The accuracy of FDG-PET and CT was similar (94%). All patients would have undergone radical nephrectomy after conventional imaging findings but FDG-PET results altered treatment decisions for 6 (35%), of whom 3 underwent partial nephrectomy and 3 avoided surgery due to confirmation of benign pathology or detection of unsuspected metastatic disease. Of the 8 cases referred for evaluation of local recurrence and/or metastatic disease FDG-PET changed treatment decisions in 4 (50%), with disease up staged in 3 and recurrence excluded in 1. Compared with CT, FDG-PET was able to detect local recurrence and distant metastases more accurately and differentiated recurrence from radiation necrosis. CONCLUSIONS: FDG-PET accurately detected local disease spread and metastatic disease in patients with renal cell carcinoma and altered treatment in 40%. FDG-PET may have a role in the diagnostic evaluation of patients with renal cell carcinoma preoperatively and staging of metastatic disease.     

Surgical strategy for aortic prosthetic graft infection with 18F-fluorodeoxyglucose positron emission tomography/computed tomography

A 30-year-old man with Marfan syndrome who underwent Crawford type II extension aneurysm repair about 9 years ago was referred to our hospital with persistent fever. Computed tomography (CT) showed air around the mid-descending aortic prosthetic graft. Because the air did not disappear in spite of intravenous antibiotics, ¹⁸F-fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) was performed. FDG-PET/CT revealed four high-uptake lesions. After dissecting the aortic graft particularly focusing on the high-uptake lesions, this patient underwent in situ graft re-replacement of descending aortic graft with a rifampicin-bonded gelatin-impregnated Dacron graft and omentopexy. The patient remains well without recurrent infection at 3 months after surgery.     

Combined use of 18F-fluorodeoxyglucose and 11C-methionine in 45 positron emission tomography-guided stereotactic brain biopsies

OBJECT: The aim of this study was to compare the contribution of the tracers 11C-methionine (Met) and 18F-fluorodeoxy-glucose (FDG) in positron emission tomography (PET)-guided stereotactic brain biopsy. METHODS: Forty-five patients underwent combined Met-PET and FDG-PET studies associated with computerized tomography (CT)- or magnetic resonance (MR)-guided stereotactic biopsy. Each patient presented with a lesion that was in proximity to the cortical or subcortical gray matter. The Met-PET and FDG-PET scans were analyzed to determine which tracer offers the best information to guide at least one stereotactic biopsy trajectory. Histologically based diagnoses were rendered in all patients (39 tumors, six nontumorous lesions) and biopsies were performed in all tumors with the aid of PET guidance. When tumor FDG uptake was higher than that in the gray matter (18 tumors), FDG was used for target definition. When FDG uptake was absent or equivalent to that in the gray matter (21 tumors), Met was used for target definition. Parallel review of all histological and imaging data showed that all tumors had an area of abnormal Met uptake and 33 had abnormal FDG uptake. All six nontumorous lesions had no Met uptake and biopsies were performed using CT or MR guidance only. All tumor trajectories had an area of abnormal Met uptake; all nondiagnostic trajectories in tumors had no abnormal Met uptake. CONCLUSIONS: When FDG shows limitations in target selection, Met is a good alternative because of its high specificity in tumors. Moreover, in the context of a single-tracer procedure and regardless of FDG uptake, Met is a better choice for PET guidance in neurosurgical procedures.     

Detecting metastatic pelvic lymph nodes by 18F-2-deoxyglucose positron emission tomography in patients with prostate-specific antigen relapse after treatment for localized prostate cancer

AIM: To evaluate whether positron emission tomography (PET) with (18)F-2-deoxyglucose (FDG) can detect pelvic lymph node metastases in prostate cancer patients who had elevated serum prostate-specific antigen (PSA) levels after treatment. METHODS: Twenty-four patients with a rising serum PSA level after treatment for localized prostate cancer were examined with FDG-PET before pelvic lymph node dissection. All patients had negative findings on whole body bone scan and equivocal pelvic computed tomography (CT) results. The results of FDG-PET were then compared to the histology of the pelvic lymph nodes obtained at surgery. RESULTS: Lymph node metastases were detected by histopathological examination in 16/24 (66.7%) patients. At the sites with histopathologically proven metastases, increased FDG uptake was found in 12/16 (75.0%) patients. In addition, there were 4 patients with false-negative results, but no patient with a false-positive result on FDG-PET images. The sensitivity, specificity, accuracy, positive predictive value, and negative predictive value of FDG-PET in detecting metastatic pelvic lymph nodes were 75.0, 100.0, 83.3, 100.0, and 67.7%, respectively. CONCLUSIONS: These results suggest that FDG-PET may be a valuable diagnostic tool in the staging of pelvic lymph nodes in patients with PSA relapse after treatment of localized prostate cancer when the whole body bone scan is negative and pelvic CT findings are equivocal.     

18F-FDG-PET uptake in non-infected total hip prostheses

Background and purpose — ¹⁸F-fluorodeoxyglucose positron emission tomography (FDG-PET) can be used in the diagnostic work-up of a patient with suspected periprosthetic joint infection (PJI) but, due to a lack of accurate interpretation criteria, this technique is not routinely applied. Since the physiological uptake pattern of FDG around a joint prosthesis is not fully elucidated, we determined the physiological FDG uptake in non-infected total hip prostheses.

Patients and methods — Patients treated with primary total hip arthroplasty (1995–2016) who underwent a FDG-PET/CT for an indication other than a suspected PJI were retrospectively evaluated. Scans were both visually and quantitatively analyzed. Semi-quantitative analysis was performed by calculating maximum and peak standardized uptake values (SUV_max and SUV_peak) by volume of interests (VOIs) at 8 different locations around the prosthesis.

Results — 58 scans from 30 patients were analyzed. In most hips, a diffuse heterogeneous uptake pattern around the prosthesis was observed (in 32/38 of the cemented prostheses, and in 16/20 of the uncemented prostheses) and most uptake was located around the neck of the prosthesis. The median SUV_max in the cemented group was 2.66 (95% CI 2.51–3.10) and in the uncemented group 2.87 (CI 2.65–4.63) (Median difference = –0.36 [CI –1.2 to 0.34]). In uncemented prostheses, there was a positive correlation in time between the age of the prosthesis and the FDG uptake (r_s = 0.63 [CI 0.26–0.84]).

Interpretation — Our study provides key data to develop accurate interpretation criteria to differentiate between physiological uptake and infection in patients with a prosthetic joint.     

Evaluation of 18F-2-deoxy-2-fluoro-<Emphasis Type="SmallCaps">d</Emphasis>-glucose Positron Emission Tomography for Gastric Cancer

Positron emission tomography (PET) with ¹⁸F-2-deoxy-2-fluoro-d-glucose (FDG) has been investigated as a means of detecting certain primary tumors and their metastatic disease in recent years. The aim of this study was to compare the performance of FDG-PET and operative assessment with formal pathologic staging. Altogether, 85 patients had undergone surgical treatment for gastric cancer with curative intent, with FDG-PET preoperatively. The results using FDG-PET were compared with those using computed tomography (CT); they were also correlated with the pathologic findings. For quantitative analysis, the regional tumor uptake was measured by the standard uptake value (SUV) using a region of interest technique. Using FDG-PET, the primary tumor was visualized in 75.2% of patients. A comparison of the FDG uptake and the clinicopathologic findings showed that there was a significant association between FDG uptake and the depth of invasion, the size of the tumor, and lymph node metastasis. FDG-PET scans had less accuracy for diagnosing locoregional lymph nodes than CT because of a significant lack of sensitivity (23.3% vs. 65.0%). The survival rate for patients with high FDG uptake (SUV > 4) was significantly lower than that for those with low FDG uptake (SUV < 4) (p < 0.05). FDG-PET was successful in detecting the primary gastric cancer lesion but not for finding early-stage gastric cancers. Detection of nodal metastasis also was not possible by FDG-PET. However, FDG-PET appears to provide important additional information concerning the aggressiveness of the tumor and the prognosis in patients with gastric cancer.     

Preoperative evaluation of thyroid nodules with 18FDG-PET/CT

BACKGROUND: Fluorine-18-fluorodeoxyglucose positron emission tomography/computed tomography ((18)FDG-PET/CT) has become an important tool in the postoperative management of de-differentiated thyroid cancer. The utility of this imaging modality in the preoperative assessment of thyroid nodules is unclear. This study was designed to determine whether (18)FDG-PET/CT improves the preoperative diagnosis of thyroid nodules. METHODS: A total of 31 patients with 48 lesions underwent fine-needle aspiration and (18)FDG-PET/CT before surgical resection of thyroid nodules. PET/CT images were obtained 1 hour after intravenous administration of (18)FDG. Standard uptake values were calculated for regions of increased (18)FDG uptake. CT scans were evaluated to identify thyroid pathology. Final pathologic diagnoses were compared with PET/CT findings. RESULTS: Fifteen of 48 lesions were malignant and 33 were benign. Nine of 15 malignant lesions were (18)FDG-avid (sensitivity 60%). Thirty of 33 benign lesions were (18)FDG-cold (specificity 91%). Positive and negative predictive values were 75% and 83%, respectively. CONCLUSIONS: (18)FDG-PET/CT provides a high negative predictive value for malignancy, making this a potentially useful tool in the evaluation of thyroid nodules with indeterminate fine-needle aspiration. However further studies with larger sample sizes are needed to determine the true efficacy of this test.     

Clinical value of [18-F]] fluorodeoxyglucose positron emission tomography imaging in soft tissue sarcomas

OBJECTIVE: To evaluate positron emission tomography (PET) using 2-fluoro-2-deoxy-D-glucose (FDG) for clinical application in soft tissue sarcomas. SUMMARY AND BACKGROUND DATA: FDG PET is a promising noninvasive method for the preoperative assessment of soft tissue sarcomas and may complement radiologic tomography. METHODS: Data from 50 consecutive patients with 59 masses, either suspicious for primary or locally recurrent soft tissue sarcoma, were prospectively gathered. The semiquantitative FDG uptake (standardized uptake values [SUVs]) was calculated in tumor and normal tissue (muscle). Histopathology of surgical specimens and follow-up data were used as control criteria. RESULTS: In primary soft tissue sarcomas, PET displayed a sensitivity of 91% and a specificity of 88%. Local recurrence was detected with a sensitivity of 88% and a specificity of 92%. All intermediate-grade and high-grade soft tissue sarcomas (primary and locally recurrent) were visualized with a precise differentiation from muscle. Fifty percent of the low-grade sarcomas showed an FDG uptake equivalent to muscle (false-negative results in one primary and three recurrent soft tissue sarcomas). Benign soft tissue tumors (e.g., lipoma, leiomyoma, ganglion) did not accumulate FDG. Inflammation resulted in an increased FDG uptake. The semiquantitative FDG uptake (SUVs) correlated with tumor grade but not with size and histologic type. CONCLUSION: High-grade and intermediate-grade soft tissue sarcomas are amenable to PET imaging, whereas low-grade lesions may not be depicted. SUVs for FDG correlate with tumor grade in soft tissue sarcomas. Benign soft tissue tumors are differentiated from higher-grade soft tissue sarcomas. These data show that FDG-PET can complement preoperative radiologic assessment for soft tissue sarcomas and that FDG-PET is a powerful diagnostic tool for detecting high-grade and intermediate-grade local recurrence.     

Incidental thyroid ��PETomas��: clinical significance and novel description of the self-resolving variant of focal FDG-PET thyroid uptake

Background

Recent series of incidental thyroid activity on fluorodeoxyglucose positron emission tomography (FDG-PET) in patients evaluated for nonthyroidal malignancy, which we refer to as a “PEToma,” have suggested that such lesions are associated with a significant incidence of primary thyroid cancer.

Methods

We retrospectively reviewed 6457 FDG-PET scans performed on 4726 patients from May 2004 to March 2007. We reviewed the cases of patients whose PET or computed tomography (CT) radiology reports described PET uptake within the thyroid to identify incidence and malignant potential of PETomas and evaluate their clinical and histopathologic features.

Results

We found that 160 patients (3.4%) had incidental, abnormal FDG uptake in the thyroid gland, 103 of whom had focal uptake (the PEToma group). Of these patients, 50 (48%) underwent further investigations, including ultrasonography in 48, fine-needle aspiration cytology in 38 and computed tomography in 3. Ten patients underwent surgery, and papillary thyroid cancer was identified in 9. The remaining 53 patients with PETomas underwent no further investigation. Interestingly, 5 patients who had focal uptake within the thyroid showed either spontaneous resolution on repeat FDG-PET (self-resolving) or no focal lesion on subsequent ultrasonography (false-positive).

Conclusion

The incidence of papillary thyroid cancer in the present series is similar to that in the literature. Although some patients will show self-resolving or false-positive focal thyroid uptake on FDG-PET, we believe that, if the patient’s clinical status permits, the evaluation of patients with incidental thyroid PEToma should include ultrasonographic confirmation and fine-needle aspiration cytology.     

Role of flourine-18 fluorodeoxyglucose positron emission tomography in thymic pathology.

OBJECTIVE: To evaluate the utilization of positron emission tomography (PET) scan with fluorine-18 fluorodeoxyglucose (FDG) in thymic pathology. METHODS: Twenty-five consecutive patients with thymic pathology underwent FDG-PET after being evaluated by computed tomography (CT). The indication for CT was myasthenia gravis in 10, anterior mediastinal mass in 7, and recurrent thymic tumor after surgical excision in 8 patients. The results of PET were compared with results obtained by CT, and histopathologic examination of the surgical specimens. RESULTS: All mediastinal abnormal thymic tissue showed FDG uptakes. FDG-PET managed to differentiate between thymic hyperplasia and thymoma in myasthenia gravis group (n=10) in which CT images were questionable in two patients. There was one case of ectopic thymic tissue which was not diagnosed preoperatively. There were no false-negative results for both CT and FDG-PET in seven patients with thymoma presented as anterior mediastinal mass. However, PET scan predicted thymic carcinoma in one patient. PET was superior to CT scan in localization of recurrent thymoma in two patients, and equal to CT in detecting metastatic lesions in six patients during the follow-up after thymoma excision. CONCLUSIONS: In myasthenia gravis, selective use of FDG-PET is useful in differentiating thymoma from hyperplasia, especially when CT scan is controversial, but fails to recognize ectopic thymic tissue. FDG-PET may differentiate thymoma from thymic carcinoma. FDG-PET is also useful in follow-up patients, who underwent thymoma excision, when there is suspicion of recurrence or metastasis.     

Lymph node staging in non-small cell lung cancer: evaluation by [18F]FDG positron emission tomography (PET)

BACKGROUND: A study was undertaken to investigate the accuracy of positron emission tomography (PET) with 2-[18F]-fluoro-2-deoxy-D- glucose (FDG) in the thoracic lymph node staging of non-small cell lung cancer (NSCLC). METHODS: Forty six patients with focal pulmonary tumours who underwent preoperative computed tomographic (CT) and FDG- PET scanning were evaluated retrospectively. Thirty two patients had NSCLC and 14 patients had a benign process. The final diagnosis was established by means of histopathological examination at thoracotomy, and the nodal classification in patients with lung cancer was performed by thorough dissection of the mediastinal nodes at surgery. RESULTS: FDG-PET was 80% sensitive, 100% specific, and 87.5% accurate in staging thoracic lymph nodes in patients with NSCLC, whereas CT scanning was 50% sensitive, 75% specific, and 59.4% accurate. The absence of lymph node tumour involvement was identified by FDG-PET in all 12 patients with NO disease compared with nine by CT scanning. Lymph node metastases were correctly detected by FDG-PET in three of five patients with N1 disease compared with two by CT scanning, in nine of 11 with N2 disease compared with six by CT scanning, an in all four with N3 nodes compared with two by CT scanning. CONCLUSIONS: FDG-PET provides a new and effective method for staging thoracic lymph nodes in patients with lung cancer and is superior to CT scanning in the assessment of hilar and mediastinal nodal metastases. With regard to resectability, FDG-PET could differentiate reliably between patients with N1/N2 disease and those with unresectable N3 disease.     

Significance of 18F-fluorodeoxyglucose positron emission tomography (FDG-PET) for detection of renal cell carcinoma and immunohistochemical glucose transporter 1 (GLUT-1) expression in the cancer

OBJECTIVE: Positron emission tomography (PET) is now primarily used in oncological indication owing to the successful application of fluorine-18 fluorodeoxyglucose (FDG) in an increasing number of clinical indications. Glucose transporter 1 (GLUT-1) is recognized as a major early marker of cellular malignant transformation. The aims of this study were to assess whether FDG-PET is a useful diagnostic tool for renal cell carcinoma and to compare the pathologic characteristics. METHODS: Nineteen consecutive patients who had renal cell carcinoma were examined using FDG-PET preoperatively. The results of PET were then compared to the histology obtained after radical surgery and the immunoreactivity of GLUT-1 was also studied. RESULTS: Pathologic examination confirmed that all 19 patients suffered from renal cell carcinoma. Increased FDG uptake was found in six of the 19 patients (31.5%). The immunohistochemical examination of GLUT-1 in renal cell carcinoma produced different results in each patient. There was no correlation with GLUT-1 immunoreactivity and FDG-PET positivity. CONCLUSION: These results suggest that FDG-PET may not be a useful diagnostic tool for renal cell carcinoma.     

FDG-PET/CT for the Preoperative Lymph Node Staging of Invasive Bladder Cancer

Background

Locoregional lymph node metastasis is an important prognostic factor in patients with bladder cancer. Multimodal treatment, depending on preoperative stage, may improve survival. The standard imaging modalities for staging (computed tomography [CT] or magnetic resonance imaging [MRI]) have an accuracy range of 70–90% for lymph node staging. A more accurate preoperative diagnostic test could improve survival rates even more.

Objective

To determine whether the use of 2-deoxy-2 [F] fluoro-D-glucose (FDG) positron emission tomography (PET) in combination with CT (FDG-PET/CT) can increase the reliability of preoperative lymph node staging in patients with nonmetastatic invasive bladder cancer (T2 or higher, M0) or recurrent high-risk superficial disease (T1G3 with or without Tis, M0).

Design, setting, and participants

Fifty-one patients underwent a preoperative FDG-PET/CT between April 2004 and December 2007. Independent of the result for lymph node status, all patients underwent a radical cystectomy and an extended lymphadenectomy. The FDG-PET/CT and CT results were compared with the definitive pathologic results.

Measurements

Among the 51 patients, 13 patients had metastatically involved locoregional lymph nodes, diagnosed on histopathology. In six patients, these nodes demonstrated increased FDG uptake on PET. In seven patients, PET/CT did not diagnose the positive lymph nodes. PET/CT was false positive in one patient.

Results and limitations

For the diagnosis of node-positive disease, the accuracy, the sensitivity, and the specificity of FDG-PET/CT were 84%, 46%, and 97%, respectively. When analysing the results of CT alone, there was accuracy of 80%, sensitivity of 46%, and specificity of 92%. The use of FDG-PET/CT is hampered by technical limitations.

Conclusions

We found no advantage for combined FDG-PET/CT over CT alone for lymph node staging of invasive bladder cancer or recurrent high-risk superficial disease.     

Detection of incidental colorectal tumours with 18F‐labelled 2‐fluoro‐2‐deoxyglucose positron emission tomography/computed tomography scans: results of a prospective study

Aim This study assessed the clinical significance of incidental colorectal 2‐fluoro‐2‐deoxyglucose (FDG) uptake using ¹⁸F‐FDG positron emission tomography/computed tomography (PET/CT) scans and evaluated the importance of colonoscopy when incidental colorectal FDG uptake was observed. Method A prospective study was designed and conducted at a single institution over a 2‐year period. In patients undergoing PET/CT scans, all with FDG uptake in the colorectum were assigned to have colonoscopy and biopsy. The value of PET/CT scanning was studied by comparison with the colonoscopy and biopsy results. Results Among 10 978 PET/CT scans, one or more focal uptakes of FDG in the colorectum were observed in 148 (1.35%) patients. In 136 valid patients, malignant colorectal tumours and polyps were found in 23.5% and 20.5%, respectively,, while the colon in the other 56% was normal. A higher false‐positive rate was found in the right colon compared with the distal colorectum (66.2%vs 36.7%, P = 0.004). A significant increase of the maximum standardized uptake (SUVmax) value was found among normal, polyps and cancer groups. Multivariate analysis revealed that SUVmax was the risk factor for predicting colorectal cancer or polyps and FDG uptake in the right colon was a negative predictive factor for finding cancers or polyps. Conclusions Our study proves the necessity of colonoscopy when incidental FDG uptake is found on PET/CT imaging. The false‐positive FDG uptake is more commonly observed in the right colon. Although the SUVmax value is higher in cancer patients, a high SUVmax value does not necessarily result in malignancies.     

Value of positron emission tomography in the diagnosis of recurrent oesophageal carcinoma

BACKGROUND: Positron emission tomography (PET) with [18F]fluorodeoxyglucose (FDG) might be useful for staging oesophageal squamous cell carcinoma (SCC). FDG-PET may be more accurate than computed tomography (CT) in diagnosing lymph node metastasis. This retrospective study compared the ability of FDG-PET and CT to diagnose recurrent oesophageal carcinoma. METHODS: Fifty-five patients with thoracic oesophageal SCC who had undergone radical oesophagectomy were studied. The accuracy of FDG-PET and CT in detecting recurrence during follow-up was calculated using data from the first images generated by either modality that suggested the presence of recurrent disease. Lesions deemed to be equivocal on these scans were considered as positive for recurrence. RESULTS: Twenty-seven of the 55 patients had recurrent disease in a total of 37 organs. Locoregional recurrence was observed in 19 patients (35 per cent). Distant recurrent disease occurred in 15 patients (27 per cent) in 18 organs. Six patients had recurrence in the liver, four in the lung, six in bone and two in distant lymph nodes. FDG-PET showed 96 per cent sensitivity, 68 per cent specificity and 82 per cent accuracy in demonstrating recurrent disease. The corresponding values for CT were 89, 79 and 84 per cent. The sensitivity of FDG-PET was higher than that of CT in detecting locoregional recurrence, but its specificity was lower because of FDG uptake in the gastric tube and thoracic lymph nodes. In distant organs the sensitivity of PET in detecting lung metastasis was lower than that of CT, but its sensitivity for bone metastasis was higher. CONCLUSION: FDG-PET has a larger field than CT. Combined PET-CT would appear to be an appropriate modality for the detection of recurrent oesophageal cancer.