Positron emission tomography in lung cancer

Recent advances in positron emission tomography (PET) with 2-deoxy-2-fluoro [F-18]-d-glucose (FDG) has enabled not only the diagnosis and staging of lung cancer but also the prediction of its malignancy grade. However, FDG-PET has been known to have several pitfalls for imaging of lung cancer. For the effective clinical use of FDG-PET in lung cancer, we reviewed the pitfalls of using FDG-PET in the diagnosis of pulmonary nodules, semiquantitative analysis of FDG-uptake, N-staging, prediction of tumor aggressiveness, prognostic significance, and prediction of pathological response after chemoradiotherapy. __________ This review was submitted at the invitation of the editorial committee.     

Role of fluorine-flurodeoxyglucose positron emission tomography/computed tomography in preoperative assessment of anterior mediastinal masses

Objective: The purpose of the study was to explore the usefulness of fluorine-fluorodeoxyglucose positron emission tomography/computed tomography (F-FDG PET-CT) in the preoperative assessment of isolated anterior mediastinal lesions, especially in the planning of operative strategy (biopsy or upfront resection). Methods: During the last 36 months, 19 consecutive patients (10 males, mean age 54 ± 16 years) underwent PET-CT in the preoperative work-up of isolated anterior mediastinal diseases. Maximal transverse diameter at CT and the postoperative histology and Masaoka staging for thymomas were collected and related to the maximum standardised uptake values (SUVs). Thymomas were divided into low-risk thymoma (LRT = A, AB and B1) and high-risk thymoma (HRT = B2, B3 and C). Results: There were 13 thymomas (six LRT and seven HRT), three lymphomas and three other primitive thymic tumours (one paraganglioma, two non-seminomatous germ cell tumours). In LRT, the mean SUV was 3.3 ± 0.5 resulting significantly lower than HRT, 13.5 ± 7 (p = 0.009). The SUV in LRT was also significantly lower with respect to lymphoma, 12.4 ± 4 (p = 0.001), and the other primitive anterior mediastinal tumours, 8 ± 0.8 (p = 0.001). Between thymomas we found a significant correlation between Masaoka stage and SUV, r = 0.718, p = 0.006. No correlation was found between transverse diameters and SUV, r = 0.141, p = 0.6. Conclusions: In our experience, low SUV (<5) is associated with LRT and minimal invasive thymoma (Masaoka stages I–II) and, therefore, susceptible to upfront surgery. For lesions with an infiltrative aspect on CT scan associated with a higher SUV (>5), an open biopsy is mandatory to exclude mediastinal lymphomas or, in case of HRT, to address a neoadjuvant treatment.     

Pulmonary <Emphasis Type="Italic">Paragonimus westermani</Emphasis> with false-positive fluorodeoxyglucose positron emission tomography mimicking primary lung cancer

We report the case of a 66-year-old woman with pulmonary Paragoniumus westermani showing false-positive fluorodeoxyglucose positron emission tomograpy (FDG-PET). Based on chest computed tomography and FDG-PET findings, we could not rule out the possibility of primary lung cancer. She underwent right middle and lower lobectomies as a primary lung cancer. As a possibility in the differential diagnosis of a pulmonary nodule with FDG-PET positive findings, paragonimiasis should be considered, although it is rarely seen.     

Pulmonary suture abscess with false-positive 18F-fluorodeoxyglucose positron emission scan mimicking lung cancer recurrence

We present the case of a 57-year-old woman with pulmonary suture abscess. She had undergone right S3 segmentectomy for early lung adenocarcinoma 7 years before and right breast-conserving surgery for invasive ductal carcinoma 5 months previously, followed by irradiation plus endocrine therapy. Chest radiography and computed tomography revealed an irregular mass (3.5 cm in diameter) between the residual S1 segment and the middle lobe, neighboring the staple line of the segmentectomy. 18F-fluorodeoxyglucose uptake into the mass increased, seen by positron emission scans. Therefore, we could not rule out the possibility of local recurrence of lung cancer and resected it. Pathologically and microbiologically, the mass was a suture abscess arising around the nylon suture of the previous segmentectomy. This lesion was the result of a foreign-body reaction, as confirmed by polarized microscopy. Moreover, titanium staples at the segmentectomy and breast-conserving surgery may also have contributed to this condition.     

Primary oligodendroglioma of the lateral ventricle with computed tomographic and positron emission tomographic evaluations

Two cases of primary intraventricular oligodendrogliomas are presented. Total excisions of well-demarcated large tumors in the lateral ventricle were successfully performed in young women by means of a frontal transventricular approach. An evaluation by computed tomography and positron emission tomography was attempted to obtain definite diagnosis of not only the location of the tumor but also the histologic grade of malignancy.     

Clinical utility of positron emission tomography in the diagnosis and management of periampullary neoplasms

Background This study examined the effect that 18-fluorodeoxyglucose positron emission tomography (¹⁸FDG-PET) imaging had on the clinical management of patients with suspected periampullary malignancy. Methods Fifty-four patients with suspected pancreatic neoplasms underwent both whole-body¹⁸FDG-PET and abdominal computed tomography (CT). Malignant or benign disease was confirmed pathologically in 47 patients. Results Of the 41 patients with malignancy,¹⁸FDG-PET failed to identify the primary tumor in 5 patients.¹⁸FDG-PET demonstrated increased uptake suggesting primary malignancy in 37 patients. Malignant pathology was confirmed in 36 cases.¹⁸FDG-PET identified malignant locoregional lymph node metastases in six of ten patients. All nodes identified before surgery by¹⁸FDG-PET were also seen on preoperative CT. Six patients who were thought to have resectable disease by CT were found to have distant metastasis at laparotomy.¹⁸FDG-PET did not detect metastasis in any of these cases. Before surgery,¹⁸FDG-PET identified distant metastases that were not detected by CT in one patient. Conclusions Despite high sensitivity and specificity in diagnosing periampullary malignancy,¹⁸FDG-PET did not change clinical management in the vast majority of patients previously evaluated by CT. In addition,¹⁸FDG-PET missed>10% of periampullary malignancies and did not provide the anatomical detail necessary to define unresectability.     

High-resolution fluorodeoxyglucose positron emission tomography with compression ("positron emission mammography") is highly accurate in depicting primary breast cancer

We sought to prospectively assess the diagnostic performance of a high-resolution positron emission tomography (PET) scanner using mild breast compression (positron emission mammography [PEM]). Data were collected on concomitant medical conditions to assess potential confounding factors. At four centers, 94 consecutive women with known breast cancer or suspicious breast lesions received 18F-fluorodeoxyglucose (FDG) intravenously, followed by PEM scans. Readers were provided clinical histories and x-ray mammograms (when available). After excluding inevaluable cases and two cases of lymphoma, PEM readings were correlated with histopathology for 92 lesions in 77 women: 77 index lesions (42 malignant), 3 ipsilateral lesions (3 malignant), and 12 contralateral lesions (3 malignant). Of 48 cancers, 16 (33%) were clinically evident; 11 (23%) were ductal carcinoma in situ (DCIS), and 37 (77%) were invasive (30 ductal, 4 lobular, and 3 mixed; median size 21 mm). PEM depicted 10 of 11 (91%) DCIS and 33 of 37 (89%) invasive cancers. PEM was positive in 1 of 2 T1a tumors, 4 of 6 T1b tumors, 7 of 7 T1c tumors, and 4 of 4 cases where tumor size was not available (e.g., no surgical follow-up). PEM sensitivity for detecting cancer was 90%, specificity 86%, positive predictive value (PPV) 88%, negative predictive value (NPV) 88%, accuracy 88%, and area under the receiver-operating characteristic curve (Az) 0.918. In three patients, cancer foci were identified only on PEM, significantly changing patient management. Excluding eight diabetic subjects and eight subjects whose lesions were characterized as clearly benign with conventional imaging, PEM sensitivity was 91%, specificity 93%, PPV 95%, NPV 88%, accuracy 92%, and Az 0.949 when interpreted with mammographic and clinical findings. FDG PEM has high diagnostic accuracy for breast lesions, including DCIS.     

The decision to operate: role of integrated computed tomography positron emission tomography in staging oesophageal and oesophagogastric junction cancer by the multidisciplinary team

OBJECTIVE: Our objective was to assess the role of fusion positron emission tomography-computed tomography (PET-CT) in staging patients for minimally invasive oesophagectomy (MIO) with potentially resectable disease from the perspective of a multidisciplinary team (MDT) deciding on operability with conventional staging investigations. METHODS: Fifty consecutive patients presenting with potentially operable oesophageal or oesophagogastric junctional tumours were staged with computed tomography (CT) and endoluminal ultrasound (EUS). The MDT categorised patients as group A (n=33; CT N0M0) or group B (n=17; CT N1/possible M1). All patients underwent FDG PET-CT. Patients with localised disease (at T3), including single level N1 disease on PET-CT, were deemed suitable for induction chemotherapy followed by surgery. RESULTS: PET-CT re-categorised 12% of patients as inoperable on grounds of distant metastases (four in group A, two in group B). Five patients did not proceed to resection for other reasons. Two had metastatic disease at thoracoscopy. Resection specimens (n=37) contained 24 nodes (median). Compared with pN status, positive predictive value of PET-CT was 40% and negative predictive value was 43%. The expected PET-CT N1 group had the highest mean number of involved nodes. Median survival for all patients (n=50) was 31.9 months for group A compared with 17.3 months for group B (not statistically significant). There was no significant difference between patients who were PET-CT N0 or N1 in survival or disease-free survival in patients undergoing surgery (n=37). CONCLUSIONS: PET-CT informs the MDT decision to operate in avoiding futile surgery in stage IV disease or widespread nodal disease. In this study, overall PET-CT N1 status has low positive and negative predictive value for overall pN status.     

Usefulness of positron emission tomography for assessing the response of neoadjuvant chemoradiotherapy in patients with esophageal cancer

BACKGROUND: In this study, we retrospectively assessed the performance of 18-F-fluorodeoxyglucose positron emission tomography (FDG-PET) compared with computed tomography (CT) and esophagography for assessing the response of advanced esophageal squamous cell carcinoma (SCC) to neoadjuvant chemoradiotherapy. METHODS: We studied 10 patients with thoracic esophageal SCC who received neoadjuvant chemoradiotherapy followed by surgery. Tumor response was assessed by CT, endoscopy, esophagography and FDG-PET before and after neoadjuvant treatment. RESULTS: Assessment of the rate of decrease in standardized uptake value (SUV) revealed a partial response (more than 50% decrease) in 5 (50%) of the patients, and assessment of length decrease of FDG uptake showed a partial response in 9 (90%) of the patients. Comparison of the histological response and the rate of decrease of various parameters revealed significant associations between histological response and tumor length (P <0.05), SUV after neoadjuvant therapy (P <0.05), and reduction in the extent of FDG uptake (P <0.01). However histological response was not significantly correlated with the rate of reduction of SUV, for both CT and esophagography. CONCLUSIONS: FDG-PET may be of considerable value for predicting the pathologic response of esophageal SCC to neoadjuvant therapy. Despite assessment of SUV before neoadjuvant therapy, low FDG uptake after therapy and reduction in the extent of FDG uptake may provide a reliable assessment of the response to therapy.     

Advantages of positron emission tomography over computed tomography in mediastinal staging of non-small cell lung cancer

BACKGROUND: New treatment algorithms in early stage non-small cell lung cancer (NSCLC) involving preoperative chemotherapy require accurate clinical staging of the mediastinum. This study compares the accuracy of 2-[fluorine-18]fluoro-2-deoxy-d-glucose (FDG) positron emission tomography (PET) scanning with that of computed tomography (CT) scanning in the clinical staging of non-small cell lung cancer. MATERIALS AND METHODS: A retrospective review was performed on 52 patients with NSCLC who were evaluated with both CT and PET scans. All patients had their mediastinal lymph nodes sampled by mediastinoscopy or at the time of thoracotomy for pulmonary resection. Each imaging study was evaluated separately and correlated with histopathologic results. RESULTS: For detecting mediastinal metastases the sensitivities of PET and CT scans were 67 and 50%, respectively; specificities were 91 and 65%, respectively; accuracies were 88 and 63%, respectively; positive predictive values were 50 and 16%, respectively; negative predictive values were 95 and 88%, respectively. PET scans were significantly better than CT scans at detecting mediastinal metastases (PET, 4/8; CT, 3/19) (P = 0.01). CONCLUSIONS: PET scanning is superior to CT scanning for clinical staging of the mediastinum in NSCLC. A more confident decision regarding stratification of patients into current treatment algorithms can be made when the decision is based on PET scanning rather than the current "gold standard" of CT scanning.     

Low thoracic muscle mass index on computed tomography predicts adverse outcomes following lobectomy via thoracotomy for lung cancer

 Open in a separate windowOBJECTIVESThe aim of this study was to determine whether the preoperative thoracic muscle mass is associated with postoperative outcomes in patients undergoing lobectomy via thoracotomy for lung cancer.METHODSConsecutive patients undergoing lobectomy were retrospectively reviewed. The thoracic muscle mass index (TMMI) was obtained at the level of the fifth thoracic vertebra on preoperative thoracic computed tomography (CT). Patients were analysed comparatively by being dividing into low and high muscle index groups by the median of sex-specific TMMI. The primary outcomes were the incidence of any or postoperative pulmonary complications. The secondary outcomes were postoperative intensive care unit (ICU) admission, length of stay (LOS) in the ICU, total hospital LOS, readmission and mortality.RESULTSThe study population consisted of 120 patients (63.6 ± 9.8 years; 74% male). Each groups included 60 patients. Major complications occurred in 28.3% (34/120) and readmission in 18.3% (22/120) of patients. The adjusted multivariable analysis showed that each unit increase in TMMI (cm²/m²) was independently associated with the rates of less any complications [odds ratio (OR) 0.92, P = 0.014], pulmonary complications (OR 0.27, P = 0.019), ICU admission (OR 0.76, P = 0.031), hospitalization for >6 days (OR 0.90, P = 0.008) and readmission (OR 0.93, P = 0.029).CONCLUSIONSLow TMMI obtained from the preoperative thoracic CT is an independent predictor of postoperative adverse outcomes in patients following lobectomy via thoracotomy for lung cancer. TMMI measurements may contribute to the development of preoperative risk stratification studies in the future.     

The role of positron emission tomography in germ cell cancer

Positron emission tomography (PET) is a non-invasive tool for imaging regional metabolic processes, which adds another dimension to current anatomy-derived imaging techniques, i.e. metabolic imaging. To date, 2-¹⁸fluoro-2-deoxy-D-glucose (FDG) has been the only tracer used for imaging germ cell tumors (GCT), which can be distinguished from normal tissue by their different glucose utilization. However, FDG PET has several limitations: (1) inflammatory and granulomatous tissues also show extensive FDG uptake, (2) lesions <1 cm in size can often not be detected, and (3) mature teratoma is indistinguishable from normal and necrotic tissue. Studies assessing the clinical role of FDG PET in GCT suggest that the technique has a place as a standard tool in evaluating post chemotherapy seminoma residuals. Whether it also improves the assessment of the risks carried by clinical stage I non-seminoma patients and the early prediction of response to salvage chemotherapy is still under investigation, or at least needs to be confirmed by further trials. In relapsing patients with a mismatch between tumor markers and imaging data, FDG PET appears to be useful whenever salvage surgery is considered, although systematic trials are not yet available.     

Brain tumor imaging with synthesized f-fluorophenylalanine and positron emission tomography

Two patients with cerebral gliomas were studied with ¹⁸F-fluorophenylalanine, newly synthesized by the electrophilic substitution reaction, using positron emission tomography. The tracer accumulated markedly in the tumor lesion and delineated the extent of the lesion. This new tracer will be promising in the diagnosis of gliomas.     

The role of positron emission tomography in the management of colorectal cancer

Positron emission tomography (PET) is a functional imaging modality that has made the transition from the research enviroment to the clinical enviroment over the last 10 years. Its major role is in the field of oncology where it is being used increasingly in the management of several tumour types including colorectal cancer. This review aims to outline the current and future role of PET scanning in the field of colorectal cancer.     

The use of 18F-FDG positron emission tomography to detect mediastinal lymph nodes in metastatic breast cancer

BackgroundTo assess the predictive value of ¹⁸F-fluorodeoxyglucose positron-emission tomography (FDG–PET/CT) in detecting mediastinal lymph node metastasis with histopathologic verification in breast cancer (BC) patients.Materials and methodsBetween February 2012 and October 2019, 37 BC patients who underwent histopathological verification for FDG-PET positive mediastinal lymph nodes were retrospectively analyzed. Nine patients (24%) were screened before beginning treatment, while 27 (76%) were screened at the time of disease progression, an average of 39 months after completion of initial treatment.ResultsThe histopathologic diagnosis revealed lymph node metastasis from BC in 15 patients (40%) and benign disease in 22 patients (60%). The standardized uptake value (SUV_max) of mediastinal lymph nodes was significantly higher in patients with lymph node metastasis compared to those with benign histology (9.0 ± 3.5 vs. 5.9 ± 2.4; P = 0.007). The cut-off value of SUV_max after the ROC curve analysis for pathological lymph node metastasis was 6.4. Two of the 15 patients with mediastinal SUV_max ≤ 6.4 and 13 of the 22 patients with SUV_max > 6.4 had lymph node metastasis. Age and pathological findings were prognostic factors for overall survival in univariate analysis. The treatment decision was changed in 19 patients (51%) after mediastinoscopic evaluation of the entire cohort.ConclusionsThis is the first study to support the need for pathologic confirmation of a positive PET/CT result following evaluation of mediastinal lymph nodes for staging BC, either at initial diagnosis or at the time of progression. Treatment decisions were consequently altered for nearly half of the patients.