Diagnostic efficacy of PET-FDG imaging in solitary pulmonary nodules. Potential role in evaluation and management

An overview of case reports and case series of pulmonary actinomycosis mimicking lung cancer: a scoping review

Background

Pulmonary actinomycosis (PA) is a rare type of Actinomyces infection that can be challenging to diagnose since it often mimics lung cancer.

Methods

Published case reports and case series of PA in patients with suspicion of lung cancer were considered, and data were extracted by a structured search through PubMed/Medline.

Results

After analyzing Medline, 31 studies were reviewed, from which 48 cases were extracted. Europe had the highest prevalence of reported cases with 45.1%, followed by Asia (32.2%), America (19.3%), and Africa (3.2%). The average age of patients was 58.9 years, and 75% of all patients were above 50 years old. Male patients (70%) were predominantly affected by PA. The overall mortality rate was 6.25%. In only eight cases, the causative agent was reported, and Actinomyces odontolyticus was the most common isolated pathogen with three cases. Based on histopathological examination, 75% of the cases were diagnosed, and the lobectomy was performed in 10 cases, the most common surgical intervention. In 50% of the cases, the selective antibiotics were intravenous and oral penicillin, followed by amoxicillin (29.1%), amoxicillin-clavulanic acid, ampicillin, levofloxacin, and doxycycline.

Conclusion

The non-specific symptoms resemble lung cancer, leading to confusion between PA and cancer in imaging scans. Radiological techniques are helpful but have limitations that can lead to unnecessary surgeries when confusing PA with lung cancer. Therefore, it is important to raise awareness about the signs and symptoms of PA and lung cancer to prevent undesirable complications and ensure appropriate treatment measures are taken.

18F-FDG PET/CT predicts acute exacerbation in idiopathic pulmonary fibrosis after thoracic surgery

Background

Acute exacerbation (AE) is the most lethal postoperative complication in idiopathic pulmonary fibrosis (IPF); however, prediction before surgery is difficult. We investigated the role of ¹⁸F-fluorodeoxyglucose positron emission tomography/computed tomography (¹⁸F-FDG PET/CT) in predicting postoperative AE in IPF.

Method

Clinical data of 48 IPF patients who underwent 18F-FDG PET/CT before thoracic surgery were retrospectively analyzed. Mean and maximal standardized uptake values (SUV_mean and SUV_max, respectively) were measured in the fibrotic area. Additionally, adjusted values-SUV ratio (SUVR, defined as SUV_max-to-liver SUV_mean ratio), tissue fraction-corrected SUV_mean (SUV_meanTF), and SUVR (SUVR_TF)-were calculated.

Results

The mean age of the subjects was 67.8 years and 91.7% were male. After thoracic surgery, 21 (43.8%) patients experienced postoperative complications including prolonged air leakage (29.2%), death (14.6%), and AE (12.5%) within 30 days. Patients who experienced AE showed higher SUV_max, SUVR, SUV_meanTF, and SUVR_TF than those who did not, but other clinical parameters were not different between patients with and without AE. The SUV parameters did not differ for other complications. The SUVR (odds ratio [OR] 29.262; P = 0.030), SUV_meanTF (OR 3.709; P = 0.041) and SUVR_TF (OR 20.592; P = 0.017) were significant predicting factors for postoperative AE following a multivariate logistic regression analysis. On receiver operating characteristics curve analysis, SUVR_TF had the largest area under the curve (0.806, P = 0.007) for predicting postoperative AE among SUV parameters.

Conclusions

Our findings suggest that ¹⁸F-FDG PET/CT may be useful in predicting postoperative AE in IPF patients and among SUVs, SUVR_TF is the best parameter for predicting postoperative AE in IPF patients.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12890-021-01659-4.

c-RAF Ablation Induces Regression of Advanced Kras/Trp53 Mutant Lung Adenocarcinomas by a Mechanism Independent of MAPK Signaling

A quarter of all solid tumors harbor KRAS oncogenes. Yet, no selective drugs have been approved to treat these malignancies. Genetic interrogation of the MAPK pathway revealed that systemic ablation of MEK or ERK kinases in adult mice prevent tumor development but are unacceptably toxic. Here, we demonstrate that ablation of c-RAF expression in advanced tumors driven by Kras^G12V/Trp53 mutations leads to significant tumor regression with no detectable appearance of resistance mechanisms. Tumor regression results from massive apoptosis. Importantly, systemic abrogation of c-RAF expression does not inhibit canonical MAPK signaling, hence, resulting in limited toxicities. These results are of significant relevance for the design of therapeutic strategies to treat K-RAS mutant cancers.

Rationale of Using Dynamic Imaging for Characterization of Suspicious Lung Masses into Benign or Malignant on Contrast Enhanced Multi Detector Computed Tomography

Objectives:

To assess the utility of dynamic imaging namely, wash-in and wash-out characteristics through multidetector contrast-enhanced computed tomography in differentiating benign and malignant pulmonary masses.

Materials and Methods:

Seventy-three patients who were suspected to have malignant pulmonary mass on the basis of clinical symptoms and chest radiograph were included in the study. All the patients underwent multidetector computed tomography scanning, and three series of images were obtained for each patient-noncontrast, early enhanced, and 15 min delayed enhanced scans. Computed tomography (CT) findings were assessed in terms of washin, absolute, and relative percentage washout of contrast. Biopsy of the mass was done and sent for histopathological evaluation. Sensitivity, specificity, and area under curve for diagnosing malignancy in the lung masses were calculated by considering both the wash-in and wash-out characteristics at dynamic CT and plotting the receiver operating curve after the final diagnosis which was obtained by histopathological evaluation.

Results:

Threshold net enhancement (washin) value of >22.5 HU had sensitivity, specificity, and diagnostic accuracy of 88.5%, 57.1%, and 82%, respectively, in predicting malignancy. Threshold relative percentage washout of <16.235% had 98.1%, 85.7%, and 94% sensitivity, specificity, and diagnostic accuracy, respectively, and threshold absolute percentage washout of <42.72% had 98.1%, 95.2%, and 95% sensitivity, specificity, and diagnostic accuracy, respectively, in predicting malignancy.

Conclusion:

Threshold net enhancement (washin), absolute and relative washout percentages can be used to predict malignancy with very high diagnostic yield, and possibly obviate the need of invasive procedures for diagnosis of bronchogenic carcinoma.

Combination diagnosis of multi-slice spiral computed tomography and secretary phospholipase A2-IIa for solitary pulmonary nodules

INTRODUCTION

This study was aimed to compare the diagnostic value of multi-slice spiral computed tomography (CT) and secretary phospholipase A2-IIa (sPLA2-IIa) in differentiating between malignant and benign solitary pulmonary nodules (SPNs).

METHODS

A total of 223 patients with SPNs (91 patients with malignant SPNs and 132 patients with benign SPNs) were included from Weihai Central Hospital during October 2014 to December 2016. SPN diagnosis was confirmed in all patients using needle biopsy, surgery and bronchoscopy. The patients were managed with dynamic multi-slice CT scans, and their sPLA2-IIa levels were also detected. By selecting the area of interest of focus, the perfusion parameters of multi-slice CT targeting the focus were obtained.

RESULTS

The levels of MTT, PS, BV, BF and sPLA2-IIa significantly increased with increasing severity of SPNs (P<.05). Notably, BV (area under the ROC curve [AUC]=0.915; 95%CI: 0.88-0.95; sensitivity=91.21%; specificity=78.79%) showed a higher potential to discriminate patients with malignant SPNs from those with benign SPNs than did BF (AUC=0.712; 95%CI: 0.65-0.78; sensitivity=72.50%; specificity=59.10%), PS (AUC=0.772; 95%CI: 0.71-0.84; sensitivity=65.93%; specificity=82.58%) and MTT (AUC=0.600; 95%CI: 0.52-0.68; sensitivity=52.75%; specificity=78.03%). Finally, the combined diagnostic value of BV and sPLA2-IIa was quite ideal (AUC=0.947; 95%CI: 0.92-0.97; sensitivity=85.70%; specificity=92.70%) for malignant and benign SPNs.

CONCLUSIONS

The combined diagnostic value of BV and sPLA2-IIa appeared as a desirable detection method for malignant and benign SPNs.

Positron emission tomography-computed tomography and 4-hydroxynonenal-histidine immunohistochemistry reveal differential onset of lipid peroxidation in primary lung cancer and in pulmonary metastasis of remote malignancies

The Aim of the study was to reveal if PET-CT analysis of primary and of secondary lung cancer could be related to the onset of lipid peroxidation in cancer and in surrounding non-malignant lung tissue.

METHODS

Nineteen patients with primary lung cancer and seventeen patients with pulmonary metastasis were involved in the study. Their lungs were analyzed by PET-CT scanning before radical surgical removal of the cancer. Specific immunohistochemistry for the major bioactive marker of lipid peroxidation, 4-hydroxynonenal (HNE), was done for the malignant and surrounding non-malignant lung tissue using genuine monoclonal antibody specific for the HNE-histidine adducts.

RESULTS

Both the intensity of the PET-CT analysis and the HNE-immunohistochemistry were in correlation with the size of the tumors analyzed, while primary lung carcinomas were larger than the metastatic tumors. The intensity of the HNE-immunohistochemistry in the surrounding lung tissue was more pronounced in the metastatic than in the primary tumors, but it was negatively correlated with the cancer volume determined by PET-CT. The appearance of HNE was more pronounced in non-malignant surrounding tissue than in cancer or stromal cells, both in case of primary and metastatic tumors.

CONCLUSIONS

Both PET-CT and HNE-immunohistochemistry reflect the size of the malignant tissue. However, lipid peroxidation of non-malignant lung tissue in the vicinity of cancer is more pronounced in metastatic than in primary malignancies and might represent the mechanism of defense against cancer, as was recently revealed also in case of human liver cancer.

Pulmonary actinomycosis mimicking lung cancer on positron emission tomography

Pulmonary actinomycosis frequently mimics lung malignancy on radiologic imaging studies. Positron emission tomography-computed tomography (PET-CT) is a useful diagnostic modality for differentiating lung malignancy from benign diseases. However, few studies evaluated PET-CT findings of pulmonary actinomycosis. Therefore, it is unclear whether PET-CT is helpful to distinguish lung malignancy from benign lung disease when pulmonary actinomycosis is clinically suspected. We investigated PET-CT findings in 11 patients with pathologically confirmed pulmonary actinomycosis. The median maximal standardized uptake value (SUV) on PET-CT of pulmonary actinomycosis was increased to 5.5 (interquartile range, 4.2-8.8), which was higher than the threshold value of 2.5 indicating malignancy. Pulmonary actinomycosis without central necrosis demonstrated higher maximal SUV of 7.5 (4.9-12.2) compared to 4.8 (3.2-5.6) of ones with central necrosis. PET-CT might be not helpful in differentiating lung malignancy from benign lesions when pulmonary actinomycosis is clinically suspected.

Dual-time-point 18F-FDG PET/CT in the diagnosis of solitary pulmonary lesions in a region with endemic granulomatous diseases

OBJECTIVE

Granulomatous diseases (GDs) can be metabolically active and indistinguishable from lung cancer on ¹⁸F-fluorodeoxyglucose positron emission tomography (¹⁸F-FDG PET) imaging. Evaluation of solitary pulmonary lesions remains a diagnostic challenge in regions with endemic GD. This study sought to determine the efficacy of dual-time-point (DTP) ¹⁸F-FDG PET/computed tomography (CT) imaging in diagnosing solitary pulmonary lesions from such regions.

METHODS

A total of 50 patients with solitary pulmonary nodules or masses with confirmed histopathological diagnoses underwent DTP ¹⁸F-FDG PET/CT imaging at 1 and 3 h after tracer injection. The maximum standardized uptake value (SUV_max) on early and delayed scans (SUV_1h and SUV_3h, respectively) and retention index (RI) were calculated for each pulmonary lesion. Receiver operating characteristic analysis was performed to evaluate the discriminating validity of the parameters.

RESULTS

There were 37 malignant and 13 benign solitary pulmonary lesions. Eight of the 13 (62 %) benign lesions were GDs. The sensitivity/specificity/accuracy of SUV_1h, SUV_3h and RI were 84/69/80 %, 84/85/84 %, and 81/54/74 %, respectively. SUV_3h had the best diagnostic performance, especially regarding specificity. The values of SUV_1h and SUV_3h were significantly different between malignant lesions and GD, while the RI values of malignant lesions and GD were both high (18.6 ± 19.5 and 18.7 ± 15.3 %, respectively; P = not significant).

CONCLUSION

SUV_3h appeared to improve the diagnostic specificity of ¹⁸F-FDG PET/CT in evaluating solitary pulmonary lesions from regions with endemic GD.

Advanced imaging tools in pulmonary nodule detection and surveillance

Lung cancer is a leading cause of death worldwide. The National Lung Screening Trial has demonstrated that lung cancer screening can reduce lung cancer specific and all cause mortality. With approval of national coverage for lung cancer screening, it is expected that an increase in exams related to pulmonary nodule detection and surveillance will ensue. Advanced imaging technologies for nodule detection and surveillance will be more important than ever. While computed tomography (CT) remains the modality of choice, other emerging modalities such as magnetic resonance imaging provides viable alternatives to CT.

MRI is unable to illustrate the absorption time of the absorbable TIGR mesh in humans: a case report

A male patient had a bilateral laparoscopic inguinal hernia repair in 2012. The right-sided hernia was treated with a permanent mesh, and the left-sided hernia received an absorbable mesh. The absorbable TIGR mesh has been proved to be completely absorbed and replaced by new connective tissue after 3 years in sheep. The patient was therefore followed for 3 years by annual magnetic resonance imagings (MRIs) to illustrate the absorption time in humans. During follow-up, the thickness of the absorbable mesh slightly decreased, and at the last clinical examination, the patient was without a recurrence. However, MRI failed to illustrate absorption of the TIGR mesh, perhaps since new connective tissue and the mesh material had the same appearance on the images. In conclusion, MRI was unable to confirm an absorption time of 3 years for the TIGR mesh, and further studies are needed to investigate if the mesh also completely absorbs in humans.

The role of ¹⁸F-FDG PET or ¹⁸F-FDG-PET/CT in the evaluation of solitary pulmonary nodules

Even with the recent advance in diagnostic tools and techniques, solitary pulmonary nodules (SPNs) remains a major clinical challenge for all doctors involved in their study. There are a wide range of diagnoses of benign and malignant lesions that can manifest as SPNs. Positron emission tomography (PET) or positron emission tomography/computed tomography (PET/CT) makes a great contribution to the diagnosis and differential diagnosis of SPNs due to the high sensitivity of pathological accumulation of (18)F-FDG. Owing to integrates the anatomical morphological and metabolic aspects in a single examination, high sensitivity and the ability to perform whole-body scans, combined PET/CT improving overall diagnosis accuracy.

Characterization of solitary pulmonary nodules with 18F-FDG PET/CT relative activity distribution analysis

OBJECTIVES

To compare the capability of relative activity distribution (RAD), a new index of fluorodeoxyglucose F18 ((18)F-FDG) uptake, with those of the typical markers for differentiating benign and malignant solitary pulmonary nodules (SPNs) by integrated positron emission tomography (PET)/computed tomography (CT).

METHODS

RAD, maximal standardised uptake value (SUV(max)), partial volume corrected SUV(max) (corrSUV(max)), and retention index (RI) were calculated prospectively for 115 malignant and 60 benign SPNs. Area under receiver operating characteristic curve (AUC), sensitivity, specificity, and accuracy were compared (P < 0.05).

RESULTS

Malignant lesions (0.98 ± 0.03) had significantly lower RAD than benign lesions (1.01 ± 0.02). AUC (0.935) was significantly larger and specificity (96.67%) was significantly higher for RAD than for SUV(max) (P ≤ 0.0001), corrSUV(max) (P < 0.0001), RI (P < 0.0001), and visual assessment (P = 0.01 and 0.002, respectively). Further, RAD had significantly higher sensitivity (92.17%) than SUV(max) (P = 0.0007) and higher accuracy (93.71%) than SUV(max) (P < 0.0001), corrSUV(max) (P < 0.0001), and RI (P = 0.002).

CONCLUSIONS

RAD seems to be more specific and accurate than the typical markers for differentiating malignant and benign SPNs by (18)F-FDG PET/CT.

KEY POINTS

• Relative activity distribution index is assessable by (18)F-FDG PET/CT • The index effectively characterises solitary pulmonary nodules • RAD is more specific and accurate than the typical markers in (18)F-FDG PET/CT • RAD provides additional options for small solitary pulmonary nodules.

Time sensitivity-corrected retention index: an enhanced metabolic index from 18F-FDG PET to differentiate between benign and malignant pulmonary nodules

The aim of the study was to evaluate pulmonary nodules (PNs) by incorporating time sensitivity (S) factor in the retention index (RI) and compare with the traditional fixed interval method. After obtaining approval from the Human Investigations Committee, 97 PNs from 81 patients (age=70±11) referred for dual-time fluorine-18 fluorodeoxyglucose PET (16.1±1.9 mCi) with definite pathological diagnosis or 1-year computed tomography follow-up were retrospectively studied. S=d{ln[SUV]]/d{ln[T]} was obtained by logarithmic regression using scan times, T (0, 1, 2), and standard uptake value (SUV) (0, 1, 2). This time-corrected RI, RIs=[(T2/T1)-1]×100%, was compared with traditional fixed time interval RI, RIx=[(SUV2/SUV1)-1]×100%, by means of receiver operating characteristic curve analysis. The mean±SD of T1 and T2 (72.3±14.0 and 134.9±17.6 min, respectively) skewed markedly from the intended time of PET scans (skewness=2.076 and 1.356, respectively). There were 27 benign tumors, 37 cases of non-small-cell lung cancer, 15 other types of cancer, and 18 stable lesions by 1-year computed tomography follow-up. There were significant differences between the nonmalignant group (NM, n=45) and the cancer group (CA, n=52) in time sensitivity (0.186±0.161 vs. 0.483±0.180, P<0.0005) and RIs (12.7±12.5 vs. 37.4±17.5%, P<0.0005). The RIx showed wider variation than RIs, although the difference between NM and CA was also significant (18.0±28.8 vs. 37.8±32.0%, P=0.002). The RIs and RIx were only weakly correlated (r=0.257, P=0.011). Receiver operating characteristic curve analysis performed for the CA or NM groups revealed a significant improvement in the diagnostic accuracy for malignancy by RIs (area under the curve=0.880±0.035, P<0.0005) compared with RIx (area under the curve=0.694±0.054, P=0.001). Incorporating the time sensitivity factor improves the diagnostic performance of RI for malignant PNs by using additional biologic information from the variation in fluorine-18 fluorodeoxyglucose uptake times and rates.

An old enemy not to be forgotten during PET CT scanning of cancer patients: tuberculosis

Aim of the study

Positron emission tomography–computed tomography (PET CT) scan is commonly used in current medical oncology practice as an imaging method. In this study we present data from cancer patients who were followed at our clinic and suspected of having tuberculosis during PET CT scanning. After the biopsy, they were diagnosed with concomitant tuberculosis.

Material and methods

In this study, 14 patients who applied to our clinic and followed up due to cancer, and had PET CT scanning for the preliminary staging or further evaluation, were included. The patients were diagnosed with metastatic or recurrent disease, and their biopsy results revealed tuberculosis.

Results

The mean age was 57.8 years with SD (standard deviation) 13.1 years and gender distribution of 78.6% (n = 11) females and 21.4% (n = 3) males. None of the patients had tuberculosis in their personal history (0%). Among the patients, 5 (35.7%) were diagnosed with tuberculosis during the preliminary staging, whereas 9 (64.3%) were diagnosed during the follow-up after the treatment. The median time to tuberculosis diagnosis was 11 months (min–max: 3–24 months) after the treatment. The most commonly involved lymph nodes during PET CT scanning were mediastinal in 8 (64.3%), axillary in 3 (21.4%) and para-aortic in 3 (21.4%) patients. The mean SUV_max (maximum standardised uptake value) of lymph node involved by PET CT scanning was defined as 8.5 (SD 2.6).

Conclusions

Despite all improvements in modern medicine, tuberculosis is still a serious public health problem. It should always be considered in differential diagnosis while evaluating PET CT scanning results of cancer patients, because it may cause false positive results.

(18)F-FDG positron-emission tomography/computed tomography findings of radiographic lesions suggesting old healed tuberculosis

The presence of radiographic lesions suggesting old healed tuberculosis (TB) is one of the strongest risk factors for the subsequent development of active TB. We elucidated the metabolic activity of radiographic lesions suggesting old healed TB using (18)F-fluorodeoxyglucose positron emission tomography/computed tomography ((18)F-FDG PET/CT). This cross-sectional study included 63 participants with radiographic lesions suggesting old healed TB and with available (18)F-FDG PET/CT scans. The maximum standardized uptake value (SUVmax) measured in the lesions, the clinical characteristics, results of the tuberculin skin test (TST) and interferon-γ release assay (IGRA) were analyzed. The SUVmax in old healed TB was 1.5 or higher among nine (14.3%) participants. Age (adjusted odds ratio [aOR], 1.23; 95% CI, 1.03-1.46), history of previous TB (aOR, 60.43; 95% CI, 1.71-2131.65), and extent of the lesions (aOR, 1.34; 95% CI, 1.02-1.75) were associated with higher SUVmax. The positive rates for the TST and IGRA were not different between groups with and without increased FDG uptake. Increased FDG uptake on (18)F-FDG PET/CT was observed in a subset of patients with radiographic lesions suggesting old healed TB. Given that the factors associated with increased FDG uptake are known risk factors for TB development, the possibility exists that participants with old healed TB lesions with higher SUV on (18)F-FDG PET/CT scans might be at higher risk for active TB.

Dynamic CT of solitary pulmonary nodules: comparison of contrast medium distribution characteristic of malignant and benign lesions

BACKGROUND

To prospectively assess the role of the dynamic contrast-enhanced CT enhancement characteristics in distinguishing malignant form of benign solitary pulmonary nodules.

METHODS

The study included 87 patients (59 men, 28 women; median age, 59 years) with 87 solitary pulmonary nodules. In all cases, dynamic CT images were obtained before and 20, 30, 45, 60, 75, 90, 120 s, 3, 5, 9, 12, 15 and 20 min after injection of contrast medium. Peak enhancement attenuation value, net enhancement attenuation value, the slope of enhancement, enhancement ratio, outflow of contrast medium (washout), washout ratio and the slope of washout ratio were assessed. Statistical analyses were performed with the Mann-Whitney test, χ(2) test, and receiver-operating characteristic curves.

RESULTS

There were 52 malignant and 35 benign nodules. There were no significant differences in net enhancement value, enhancement ratio and the slope of enhancement ratio between malignant and benign nodules (P > 0.05). Malignant nodules showed smaller outflow of contrast medium than did benign nodules. With 12.4HU or lower washout as a cutoff value, the sensitivity and specificity for malignancy were 52.5 and 65.0 %, respectively. With 18.9 % or lower washout ratio as a cutoff value, sensitivity and specificity for malignancy were 60.0 and 75.0 %, respectively. With 0.0180 %/s or lower slope of washout ratio as a cutoff value, sensitivity and specificity for malignancy were 60.0 and 80.0 %, respectively.

CONCLUSIONS

Dynamic contrast-enhanced CT is helpful in differentiating malignant from benign solitary pulmonary nodules. Smaller washout of contrast enhancement is a predictor that a lesion is malignant.

Computer-aided diagnosis systems for lung cancer: challenges and methodologies

This paper overviews one of the most important, interesting, and challenging problems in oncology, the problem of lung cancer diagnosis. Developing an effective computer-aided diagnosis (CAD) system for lung cancer is of great clinical importance and can increase the patient's chance of survival. For this reason, CAD systems for lung cancer have been investigated in a huge number of research studies. A typical CAD system for lung cancer diagnosis is composed of four main processing steps: segmentation of the lung fields, detection of nodules inside the lung fields, segmentation of the detected nodules, and diagnosis of the nodules as benign or malignant. This paper overviews the current state-of-the-art techniques that have been developed to implement each of these CAD processing steps. For each technique, various aspects of technical issues, implemented methodologies, training and testing databases, and validation methods, as well as achieved performances, are described. In addition, the paper addresses several challenges that researchers face in each implementation step and outlines the strengths and drawbacks of the existing approaches for lung cancer CAD systems.

Characterization of pulmonary lesions in patients with suspected lung cancer: computed tomography versus [¹⁸F] fluorodeoxyglucose-positron emission tomography/computed tomography

Pulmonary nodules are of high clinical importance, given they may prove to be an early manifestation of lung cancer. Pulmonary nodules are small, focal, radiographic opacities that may be solitary or multiple. A solitary pulmonary nodule is a single, small (≤30 mm in diameter) opacity. Larger opacities are called masses and are often malignant. As imaging techniques improve and more nodules are detected, the optimal management of pulmonary nodules remains unclear. However, the question of malignancy of any given nodule remains the same. A standard contrast-enhanced computed tomography (CT) scan is often the first examination, followed by a number of other examinations. The purpose of this study was to examine the clinical feasibility of CT versus integrated [¹⁸F]fluorodeoxyglucose-positron emission tomography (PET)/low-dose CT scan in patients with suspected lung cancer and pulmonary lesions on CT. All results were controlled for reproducibility. We found that when used early in the work-up of the lesions, CT raised the prevalence of lung cancer in the population to the point where further diagnostic imaging examination could be considered futile. We also found that the overall diagnostic accuracy, as well as the classification probabilities and predictive values of the two modalities were not significantly different; the reproducibility of these results was substantial.

Solitary pulmonary nodules differentiated by dynamic F-18 FDG PET in a region with high prevalence of granulomatous disease

This study determined whether dynamic F-18 FDG PET imaging could differentiate benign from malignant solitary pulmonary nodules (SPNs). Histopathologically confirmed SPNs (10-35 mm), 24 malignant and 10 benign, from 34 patients were studied through both dynamic and static F-18 FDG PET imaging of all patients. Volumes of interest (VOIs) were placed over the pulmonary nodules using a 50% maximum pixel value threshold. The arterial input function was estimated from a left ventricle-defined VOI. Based on Patlak analysis, we calculated the net FDG phosphorylation rate (K(i)) and glucose metabolic rate (MRGlu) of each nodule. The slope values of the time-activity curves (TACs) of the nodules were also determined. Based on the static PET images, maximum and mean standardized uptake values (SUV(max) and SUV(mean), respectively) were calculated. Benign and malignant SPNs had significantly different values for SUV(max), SUV(mean), K(i), MRGlu, and TAC slope, with area under the receiver operating characteristic curves distinguishing benign from malignant nodules. McNemar's test of marginal homogeneity found all the predictors helpful to detect malignant nodules (all, p > 0.05), and combining K(i) and MRGlu, which were generated by dynamic study, yielded a higher specificity of 90%, and a sensitivity of 79%. Among the 10 benign nodules, static SUV imaging correctly classified seven, while dynamic F-18 PET imaging correctly classified nine. Dynamic F-18 FDG PET imaging is valuable in differentiating benign from malignant SPNs, particularly for granulomatous disease.

Characterization of solitary pulmonary nodules: Use of washout characteristics at contrast-enhanced computed tomography

The purpose of this study was to determine whether computed tomographic scans and attenuation measurements on contrast material-enhanced and non-enhanced computed tomographic scans could be used to characterize solitary pulmonary nodules and, in particular, to characterize these lesions using washout characteristics on contrast-enhanced computed tomography. A total of 63 patients (38 males, 25 females; age range, 21-80 years; mean age, 58±13.2 years) with pulmonary nodules revealed on contrast-enhanced computed tomography underwent 20-min delayed enhanced scans. The mean diameter of the pulmonary nodules was 1.8±0.6 cm (range, 0.8-2.9). Region-of-interest measurements were obtained at non-enhanced, dynamic enhanced and delayed enhanced computed tomography and were used to calculate a relative percentage washout as follows: 1 - (Hounsfield unit measurement on delayed image/Hounsfield unit measurement on dynamic image) × 100%. There was a mean relative washout of 33% on the delayed computed tomographic scans (range, 12-46) in benign solitary pulmonary nodules; and a mean relative washout of 7% (range, -36-51) in malignant solitary pulmonary nodules (Mann-Whitney U test, p<0.001). Results of the receiver operating curve analysis revealed that a threshold relative washout of 14.5% had 74.3% sensitivity and 92.9% specificity for identifying malignant nodules. Calculation of the relative percentage washout on dynamic and delayed enhanced computed tomographic scans may lead to a highly specific test for solitary pulmonary nodule characterization and reduce the need for, and possibly obviate, follow-up imaging or biopsy.

Computer-assisted detection of infectious lung diseases: a review

Respiratory tract infections are a leading cause of death and disability worldwide. Although radiology serves as a primary diagnostic method for assessing respiratory tract infections, visual analysis of chest radiographs and computed tomography (CT) scans is restricted by low specificity for causal infectious organisms and a limited capacity to assess severity and predict patient outcomes. These limitations suggest that computer-assisted detection (CAD) could make a valuable contribution to the management of respiratory tract infections by assisting in the early recognition of pulmonary parenchymal lesions, providing quantitative measures of disease severity and assessing the response to therapy. In this paper, we review the most common radiographic and CT features of respiratory tract infections, discuss the challenges of defining and measuring these disorders with CAD, and propose some strategies to address these challenges.

The utility of the nonattenuation corrected 18F-FDG PET images in the characterization of solitary pulmonary lesions

OBJECTIVE

To determine the accuracy of nonattenuation corrected (NAC) F-fluorodeoxyglucose positron emission tomography (F-FDG PET) images in the evaluation of solitary pulmonary lesion as compared with more established methods.

METHODS

Fifty-six patients received F-FDG PET/CT for diagnosing solitary pulmonary nodules or mass lesions based on histopathology (n=39) and clinical follow-up (n=17). Visual pulmonary lesion FDG uptake was graded by consensus of two nuclear medicine physicians on both attenuation corrected (AC) [absent, less than mediastinal blood pool (MBP), equal to MBP, greater than MBP] and NAC (absent, less than skin, equal to skin, greater than skin) images. Standardized uptake values (SUV) were also measured from AC images. SUV, visual AC, and visual NAC methods' diagnostic performances were compared, distinguishing benign from malignant pulmonary nodules.

RESULTS

There were 34 malignant and 22 benign lesions. Lesion diameter varied from 5 to 100 mm (mean ± SD, 24.0 ± 17.9 mm). The NAC, AC, and SUV method sensitivities and specificities were 100/64%, 91/59%, and 79/77%, respectively. For lesions less than 3 cm, NAC, AC, and SUV methods yielded accuracies of 85%, 78%, and 73%, respectively. The NAC method was the most sensitive and accurate especially for small nodules.

CONCLUSION

Visual assessment of NAC F-FDG PET images alone may provide a more accurate characterization of solitary pulmonary lesions.

The role of dual time point FDG PET imaging in the evaluation of solitary pulmonary nodules with an initial standard uptake value less than 2.5

AIM

To evaluate the accuracy of dual time point 2-[(18)F]-fluoro-2-deoxy-d-glucose (FDG) positron-emission tomography (PET) imaging in the evaluation of the mildly metabolic solitary pulmonary nodule (SPN) and to assess whether accuracy could be improved by delaying second image acquisition to 180 minutes.

MATERIALS AND METHODS

Fifty-four patients were included in the study. Thirty-six had an SUV(max) <2.5 at 60 min. For these patients, two methods of interpreting the subsequent delayed FDG PET imaging at 180 min were investigated. The first method analysed the SUV(max) of SPNs on delayed imaging, in which an SUV(max) of 2.5 or more was regarded as a criterion for malignancy. The second method was retention index (RI) analysis, in which an increase of 10% or more in SUV(max) between the initial and delayed images, was regarded as an indication of malignancy.

RESULTS

For the group as a whole (n=54), the sensitivity, specificity and accuracy of using an SUV(max) of 2.5 or more as an indication of malignancy at the time of initial image acquisition (60 min) was 58, 89, and 74%, respectively. For SPNs that had an initial SUV(max) <2.5 (n=36), the sensitivity, specificity, and accuracy of using an SUV(max) of 2.5 or more as a criterion for malignancy on the delayed image acquisition (180 min), was 36, 96, and 78% respectively. However, if an RI of >10% was used as a criterion for malignancy between the initial and delayed images, the sensitivity, specificity, and accuracy was 73, 80, and 78%, respectively. These results are similar to a recent paper, where image acquisition occurred at 60 and 120 min post-tracer injection.

CONCLUSION

Dual time point FDG PET imaging with RI analysis, is a useful technique in evaluating SPN with an initial SUV(max) <2.5. Prolonging second image acquisition from 120 to 180 min does not appear to improve the accuracy of this technique. However, given that maximal FDG uptake by lung carcinomas is thought to be in the region of 5h, it may be that improving the accuracy of dual time point FDG PET imaging requires a more significant delay in second image acquisition in this specific subgroup.

Metastases in mediastinal and hilar lymph nodes in patients with non-small cell lung cancer: quantitative assessment with diffusion-weighted magnetic resonance imaging and apparent diffusion coefficient

OBJECTIVE

To evaluate diffusion-weighted magnetic resonance (DW-MR) imaging for detection of metastases in lymph nodes by using quantitative analysis.

METHODS

Seventy patients with non-small cell lung cancer were examined with DW and short inversion time inversion recovery (STIR) turbo-spin-echo MR imaging. Apparent diffusion coefficient of each lung cancer and lymph node was calculated from DW-MR images. Difference of the apparent diffusion coefficient in a lung cancer and a lymph node was calculated (D1). From STIR turbo-spin-echo MR images, ratios of signal intensity in a lymph node to that in a 0.9% saline phantom was calculated (lymph node-saline ratio [LSR1]). For quantitative analysis, the threshold value for a positive test was determined on a per node basis and tested for ability to enable a correct diagnosis on a per patient basis. Results of quantitative analyses of DW- and STIR-MR images were compared on a per patient basis with McNemar testing.

RESULTS

Mean D1 in the lymph node group with metastases was lower than that in the group without metastases (P < 0.001). When an D1 of 0.24 x 10(-3) mm2/s was used as the positive test threshold, sensitivity, specificity, and accuracy were 69.2%, 100%, and 94.0%, respectively, on a per patient basis. There was no significant difference (P > 0.05) between quantitative analyses of DW-MR images and STIR-MR images.

CONCLUSIONS

Quantitative analysis of DW-MR images enables differentiation of lymph nodes with metastasis from those without.

Dual-time-point [18F]-FDG PET/CT in the diagnostic evaluation of suspicious breast lesions

PURPOSE

The authors sought to evaluate whether the reacquisition of images 3 h after administration of radiotracer improves the sensitivity of fluorine-18 fluorodeoxyglucose positron emission tomography computed tomography ([(18)F]-FDG PET/CT) in patients with suspicious breast lesions.

MATERIALS AND METHODS

Forty-eight patients with 59 breast lesions underwent an [(18)F]-FDG PET/CT study in the prone position with a dual-time-point acquisition performed in the early phase 1 h after FDG administration (PET-1) and in the delayed phase 3 h after FDG administration (PET-2). Both examinations were evaluated qualitatively and semiquantitatively with calculation of the mean percentage variation of the standard uptake values (Delta% SUV(max)) between PET-1 and PET-2. All lesions with an SUV(max) >or=2.5 at PET-1 or a reduction in SUV between PET-1 and PET-2 were considered benign. The definitive histopathological diagnosis was available for all patients included in the study.

RESULTS

The dual-time-point acquisition of [(18)F]-FDG PET/CT displayed an accuracy of 85% for lesions with an SUV(max) >or=2.5 and/or positive Delta% SUV(max), with sensitivity and specificity values of 81% and 100% compared with 69%, 63% (both p<0.001) and 100% (p=n.s.), respectively, for the single-time-point acquisition. Malignant lesions showed an increase in FDG uptake between PET-1 and PET-2, with a Delta% SUV(max) of 10+/-7 (p<0.04). In contrast, benign lesions showed a decrease in SUV between PET-1 and PET-2, with a Delta% SUV(max) of -21+/-7 (p<0.001).

CONCLUSIONS

The delayed repeat acquisition of PET images improves the accuracy of [(18)F]-FDG PET/CT in patients with suspicious breast lesions with respect to the single-time-point acquisition. In addition, malignant breast lesions displayed an increase in FDG uptake over time, whereas benign lesions showed a reduction. These variations in FDG uptake between PET-1 and PET-2 are a reliable parameter that can be used for differentiating between benign and malignant breast lesions.

Detection and prediction of local recurrence of maxillary sinus cancer using F-18 FDG PET/CT

PURPOSE

The aim of the current study was to investigate the role of F-18 FDG PET/CT in the detection and prediction of local recurrence of maxillary sinus cancer.

METHODS

Retrospectively, we analyzed F-18 FDG PET/CT images of maxillary sinus cancer patients for the surveillance after treatment. Twenty-two consecutive patients with maxillary sinus cancer, who underwent maxillectomy followed by adjuvant radiation treatment, were included in the study. F-18 FDG PET/CT images were analyzed visually and quantitatively.

RESULTS

The median age of the patients included in the current study population was 54.5 years (range, 35-78). Seven patients (29.1%) had local recurrent diseases. Recurrent diseases show statistically significant higher values in SUV(max) (recurrent: 5.09 +/- 3.3, non-recurrent; 3.05 +/- 0.7, p < 0.05), L/NL (recurrent: 2.95 +/- 0.9, non-recurrent; 1.86 +/- 0.5, p < 0.05), L/Ao (recurrent: 3.37 +/- 2.1: non-recurrent; 1.88 +/- 0.4, p < 0.05), and L/Cbr (recurrent: 1.06 +/- 0.7: non-recurrent; 0.46 +/- 0.1, p < 0.05) than those of non-recurrent disease of maxillary sinus cancer. There were no statistical differences between visual assessment and quantitative indices for the detection of local recurrence. The visual assessment was the potent predictor by logistic regression analysis for prediction of local recurrence.

CONCLUSION

The visual assessment of F-18 FDG uptake pattern was potential predictor for local recurrence of maxillary sinus cancer. However, the diagnostic performances were similar between visual assessment and quantitative indices. Further studies are needed to confirm these results and improve statistical accuracy.

Abnormal 18F-FDG Uptake Detected with Positron Emission Tomography in a Patient with Breast Cancer: A Case of Sarcoidosis and Review of the Literature

18F-FDG PET is a useful and sensitive imaging method for a variety of malignancies, however, the specificity is low in active infections and inflammatory diseases. We describe a female patient with stage IIIA breast cancer in first complete remission with combination chemotherapy who developed nodular formations in the lung and axilla 12 years later. Imaging studies as well as FDG PET showed nodular lesions and increased metabolic activity which was interpreted as the progression of the primary disease. She was first given combination chemotherapy and hormonal therapy but was proven thereafter to have sarcoidosis by pathologic examination and was successfully treated with corticosteroid treatment.

An unusual presentation of a sarcoidosis that mimicked lymphatic metastatize non small cell lung carcinoma in positron emission tomography: a case report

In the last decade, several sophisticated and accurate imaging methods such as positron emission tomography have been developed in order to evaluate malignant potential in enlarged mediastinal lymph nodes. This case illustrates an unusual presentation of sarcoidosis that mimicked lymphatic metastases of non small cell lung carcinoma. The reported high specificity and sensitivity of positron emission tomography-Computer Tomography regarding mediastinal staging could lead in same cases of false positives to a delaying of stage adapted therapy of non small cell lung carcinoma, showing that despite the recent advances of imaging techniques, such as positron emission tomography-computer tomography, several limitations of this imaging technique are still existing.

Time benefit in the assessment of recurrences following fractionated radiotherapy in an experimental tumour system using positron‐emission tomography with18F‐fluorodeoxyglucose

PURPOSE

To determine the sensitivity and specificity of 18F-fluorodeoxyglucose-positron-emission tomography (FDG-PET) in the diagnosis of R1H tumours after fractionated radiotherapy, and the dependency of sensitivity and specificity on time after therapy. In addition, the time benefit of FDG-PET concerning early recognition of recurrences after fractionated radiotherapy was assessed.

MATERIAL AND METHODS

Subcutaneously growing rat rhabdomyosarcoma R1H tumours were irradiated by applying total doses of 80 or 85 Gy after reaching a start volume of 0.8 cm3. Twenty animals were treated. Tumour volume was determined twice a week. FDG-PET was performed weekly before, during and for 6 months after therapy using a conventional full-ring whole-body PET scanner. In total, 600 PET results were evaluated qualitatively using a six-scale score. PET results and actual tumour volumes were compared. The sensitivity and specificity of tumour detection by PET was calculated for different times after the onset of therapy. The optimal score for tumour detection and the influence of time after therapy on the quality of PET (time benefit) was evaluated using receiver-operating characteristics.

RESULTS

After irradiation, 8/20 tumours (40%) were locally controlled, while 12/20 recurred. In this tumour model, evidence of relapse is assured when a volume of 0.1 cm3 is reached. Sensitivity of tumour diagnosis by PET increases with time, i.e. with the volume of recurrent tumours after the onset of therapy, mounting to > 0.95 after 100 days. Specificities of 0.95-1.0 were determined after therapy, showing no increase with time. Tumour diagnosis by PET is highly accurate when performed 80 days after the start of treatment. On average, tumours were recognized by PET on 31, 62, 74 and 81 days (median) before approaching volumes of 0.2, 0.5, 0.8 or 1.0 cm3, respectively.

CONCLUSION

An experimental system was implemented that allows reproducible detection of recurrent R1H tumours after radiotherapy using FDG-PET. The usefulness of PET as a diagnostic test for R1H tumours is very good and a reliable resolution for PET is demonstrated for volumes < 1 cm3. The results indicate that FDG-PET enables early recognition of recurrences after fractionated radiotherapy.

68Ga-DOTA-NOC: a new PET tracer for evaluating patients with bronchial carcinoid

BACKGROUND

Conventional imaging techniques [computed tomography (CT), ultrasound, magnetic resonance] and somatostatin receptor scintigraphy are often insufficient to make a conclusive diagnosis of bronchial carcinoid (BC). PET is commonly used for the assessment of lung cancer but 18F-fluorodeoxyglucose, the most frequently used PET tracer, presents a low sensitivity for the detection of neuroendocrine tumours (NETs). New PET radiopharmaceuticals such as 68Ga-DOTA peptides, which directly bind to somatostatin receptors and are usually expressed on NET cell surfaces, have been reported to be superior to both morphological and somatostatin receptor scintigraphy imaging for gastroenteropancreatic NETs. However, their role in BC has never been evaluated. Our aim is to evaluate the role of 68Ga-DOTA-NOC (68Ga-labelled [1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid]-1-Nal3-octreotide) PET for the assessment of BC patients.

METHODS

Ten patients with pathologically proven well-differentiated BC and one patient with highly suggestive CT images for BC were studied by 68Ga-DOTA-NOC PET/CT. PET findings were compared with clinical follow-up, pathology and contrast-enhanced CT findings.

RESULTS

68Ga-DOTA-NOC PET/CT detected at least one lesion in nine of 11 patients and was negative in two. PET/CT and contrast-enhanced CT were discordant in eight of 11 patients, whereas in only three patients both provided similar results. PET/CT detected a higher number of lesions in five patients and excluded malignancy at sites considered positive on CT in three of 11; follow-up confirmed PET/CT findings in all patients. In PET/CT-positive patients, the mean maximal standardized uptake value was 25.9 [4.4-60.5]. On a clinical basis, PET/CT provided additional information in nine of 11 patients leading to the changes in the clinical management of three of nine patients.

CONCLUSION

PET/CT with Ga-DOTA-NOC was useful in BC patients because it led to a better evaluation of the extent of the disease.

Integrated FDG-PET/CT vs. standard radiological examinations: comparison of capability for assessment of postoperative recurrence in non-small cell lung cancer patients

PURPOSE

The purpose of this study was to prospectively and directly compare diagnostic capabilities of whole-body integrated FDG-PET/CT and standard radiologic examination for assessment of recurrence in postoperative non-small cell lung cancer (NSCLC) patients.

MATERIALS AND METHODS

A total of 92 consecutive pathologically diagnosed NSCLC patients (65 males, 27 females; mean age, 71 years) underwent pathologically and surgically proven complete resection, followed by prospective whole-body FDG-PET/CT and standard radiological examinations. Final diagnosis of recurrence was based on the results of more than 1 year of follow-up and/or pathological examinations. On both methods, the probability of recurrence was assessed in each patient by using a five-point visual scoring system, and the each final diagnosis was made by consensus between two readers. Kappa analyses were performed to determine inter-observer agreement for both methods, and ROC analyses were used to compare capability of the two methods for assessment of postoperative recurrence on a per-patient basis. Sensitivity, specificity and accuracy were also compared between PET/CT and standard radiological examination by means of McNemar's test.

RESULTS

All inter-observer agreements were almost perfect (integrated PET/CT: kappa=0.89; standard radiological examination: kappa=0.81). There were no statistically significant differences in area under the curve, sensitivity, specificity and accuracy between integrated FDG-PET/CT and standard radiologic examinations (p>0.05).

CONCLUSION

Integrated FDG-PET/CT can be used for assessment of postoperative recurrence in NSCLC patients with accuracy as good as that of standard radiological examinations.

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.