Small Solitary Pulmonary Nodules Research Articles

Nomogram for predicting invasive lung adenocarcinoma in small solitary pulmonary nodules.

This study aimed to construct a clinical prediction model and nomogram to differentiate invasive from non-invasive pulmonary adenocarcinoma in solitary pulmonary nodules (SPNs). We analyzed computed tomography and clinical features as well as preoperative biomarkers in 1,106 patients with SPN who underwent pulmonary resection with definite pathology at Qilu Hospital of Shandong University between January 2020 and December 2021. Clinical parameters and imaging characteristics were analyzed using univariate and multivariate logistic regression analyses. Predictive models and nomograms were developed and their recognition abilities were evaluated using receiver operating characteristic (ROC) curves. The clinical utility of the nomogram was evaluated using decision curve analysis (DCA). The final regression analysis selected age, carcinoembryonic antigen, bronchus sign, lobulation, pleural adhesion, maximum diameter, and the consolidation-to-tumor ratio as associated factors. The areas under the ROC curves were 0.844 (95% confidence interval [CI], 0.817-0.871) and 0.812 (95% CI, 0.766-0.857) for patients in the training and validation cohorts, respectively. The predictive model calibration curve revealed good calibration for both cohorts. The DCA results confirmed that the clinical prediction model was useful in clinical practice. Bias-corrected C-indices for the training and validation cohorts were 0.844 and 0.814, respectively. Our predictive model and nomogram might be useful for guiding clinical decisions regarding personalized surgical intervention and treatment options.

Nomogram combining clinical and radiological characteristics for predicting the malignant probability of solitary pulmonary nodules measuring ≤ 2 cm.

At present, how to identify the benign or malignant nature of small (≤ 2 cm) solitary pulmonary nodules (SPN) are an urgent clinical challenge. This retrospective study aimed to develop a clinical prediction model combining clinical and radiological characteristics for assessing the probability of malignancy in SPNs measuring ≤ 2 cm. In this study, we included patients with SPNs measuring ≤ 2 cm who underwent pulmonary resection with definite pathology at Qilu Hospital of Shandong University from January 2020 to December 2021. Clinical features, preoperative biomarker results, and computed tomography characteristics were collected. The enrolled patients were randomized at a ratio of 7:3 into a training cohort of 775 and a validation cohort of 331. The training cohort was used to construct the predictive model, while the validation cohort was used to test the model independently. Univariate and multivariate logistic regression analyses were performed to identify independent risk factors. The prediction model and nomogram were established based on the independent risk factors. The receiver operating characteristic (ROC) curve was used to evaluate the identification ability of the model. The calibration power was evaluated using the Hosmer-Lemeshow test and calibration curve. The clinical utility of the nomogram was also assessed by decision curve analysis (DCA). A total of 1,106 patients were included in this study. Among them, the malignancy rate of SPNs was 85.08% (941/1,106). We finally identified the following six independent risk factors by logistic regression: age, carcinoembryonic antigen, nodule shape, calcification, maximum diameter, and consolidation-to-tumor ratio. The area under the ROC curve (AUC) for the training cohort was 0.764 (95% confidence interval [CI]: 0.714-0.814), and the AUC for the validation cohort was 0.729 (95% CI: 0.647-0.811), indicating that the prediction accuracy of nomogram was relatively good. The calibration curve of the predictive model also demonstrated a good calibration in both cohorts. DCA proved that the clinical prediction model was useful in clinical practice. We developed and validated a predictive model and nomogram for estimating the probability of malignancy in SPNs measuring ≤ 2 cm. With the application of predictive models, thoracic surgeons can make more rational clinical decisions while avoiding overtreatment and wasting medical resources.

PERIOPERATIVE SMALL LUNG NODULE LOCALIZATION FOR MINIMALLY INVASIVE THORACIC SURGERY WITH AN ELECTROMAGNETIC NAVIGATIONAL SYSTEM

PERIOPERATIVE SMALL LUNG NODULE LOCALIZATION FOR MINIMALLY INVASIVE THORACIC SURGERY WITH AN ELECTROMAGNETIC NAVIGATIONAL SYSTEM

Clinical-radiological predictive model in differential diagnosis of small (\u2264\u200920\xa0mm) solitary pulmonary nodules

BackgroundThere is a lack of clinical-radiological predictive models for the small (≤ 20 mm) solitary pulmonary nodules (SPNs). We aim to establish a clinical-radiological predictive model for differentiating malignant and benign small SPNs.Materials and methodsBetween January 2013 and December 2018, a retrospective cohort of 250 patients with small SPNs was used to construct the predictive model. A second retrospective cohort of 101 patients treated between January 2019 and December 2020 was used to independently test the model. The model was also compared to two other models that had previously been identified.ResultsIn the training group, 250 patients with small SPNs including 156 (62.4%) malignant SPNs and 94 (37.6%) benign SPNs patients were included. Multivariate logistic regression analysis indicated that older age, pleural retraction sign, CT bronchus sign, and higher CEA level were the risk factors of malignant small SPNs. The predictive model was established as: X = − 10.111 + [0.129 × age (y)] + [1.214 × pleural retraction sign (present = 1; no present = 0)] + [0.985 × CT bronchus sign (present = 1; no present = 0)] + [0.21 × CEA level (ug/L)]. Our model had a significantly higher region under the receiver operating characteristic (ROC) curve (0.870; 50% CI: 0.828–0.913) than the other two models.ConclusionsWe established and validated a predictive model for estimating the pre-test probability of malignant small SPNs, that can help physicians to choose and interpret the outcomes of subsequent diagnostic tests.

ROLE OF LUNG POINT NAVIGATION BRONCHOSCOPY IN THE DIAGNOSIS OF PULMONARY NODULE

Background: Pulmonary nodules are one of the most common thoracic imaging abnormalities. A revised estimate of over 1 million nodules are detected each year as an incidental finding, either on chest radiographs or thoracic computed tomography (CT) scans However, an accurate diagnosis from these small, peripheral lung lesions can still be challenging with the use of conventional procedures.The lung point navigation bronchoscopy seems safe and effective. Navigation support with fluoroscopic guidance more successful in sampling small Solitary Pulmonary Nodules, increasing the likelihood of a diagnosis and decreasing the need for surgical biopsy . Aim of the work: To detect the role of the lung point navigation bronchoscopy in diagnosis of pulmonary nodule. PATIENTS AND METHODS: This study was performed between January 2019 and October 2019 in the bronchoscopy unit of Chest hospital of Military Kobri Al-Kobba medical Complex, It was prospective cross-sectional analytic study conducted on 30 patients to detect the role of the lung point navigation system in diagnosis of pulmonary nodule. Conclusion: Diagnosis of pulmonary nodule by navigated bronchoscopy with the lung point system seems safe and effective. Navigation support with fluoroscopic guidance may be more successful in sampling small and peripherally located pulmonary nodule, increasing the likelihood of a diagnosis and decreasing the need for surgical biopsy.

The multidisciplinary team plays an important role in the prediction of small solitary pulmonary nodules: a propensity-score-matching study.

According to guidelines, it is recommended that pulmonary nodules be discussed by a multidisciplinary team (MDT); however, the evidence for the effectiveness of MDT is sparse. To demonstrate the importance of the involvement of an MDT for the prediction of small solitary pulmonary nodules, we conducted this retrospective study. The patient database of those who attended our MDT and the electronic medical record system of our hospital was used; we collected all the data from patients found with small solitary pulmonary nodules (≤2 cm), which were suspected as malignant and who received a resection of the nodules. We summarized their characteristics and analyzed them, and then compared the post-operation pathological diagnosis of the patients who attended an MDT to those who did not participate in an MDT during the same period (2017-2019.2). We also collected the follow-up data. Propensity-score-matching was utilized during the process of analysis to get a more reliable conclusion. Most of the qualified patients were female. Most of the small solitary pulmonary nodules (≤2 cm) were adenocarcinoma and located on the right upper lobe. There were no differences in the SUV value between malignant nodules and benign nodules. After propensity-score matching, the total positive prediction value of small solitary pulmonary nodules (≤2 cm) without an MDT was 69.4%, while that with MDT was 77.6%; the difference was not significant with a P value of 0.30. The negative predictive value of MDT was 76.2%. In developing countries, small solitary pulmonary nodules tend to be more correctly diagnosed with MDT.

Nomogram For The Prediction Of Malignancy In Small (8-20 mm) Indeterminate Solid Solitary Pulmonary Nodules In Chinese Populations.

PurposeThis study aimed to develop and validate a nomogram for predicting the malignancy of small (8–20 mm) solid indeterminate solitary pulmonary nodules (SPNs) in a Chinese population by using routine clinical and computed tomography data.MethodsThe prediction model was developed using a retrospective cohort that comprised 493 consecutive patients with small indeterminate SPNs who were treated between December 2012 and December 2016. The model was independently validated using a second retrospective cohort comprising 216 consecutive patients treated between January 2017 and May 2018. The investigated variables included patient characteristics (e.g., age and smoking history), nodule parameters (e.g., marginal spiculation and significant enhancement), and tumor biomarker levels (e.g., carcinoembryonic antigen). A prediction model was developed by using multivariable logistic regression analysis, and the model’s performance was presented as a nomogram. The model was evaluated based on its discriminative ability, calibration, and clinical usefulness.ResultsThe developed nomogram was ultimately based on age, marginal spiculation, significant enhancement, and pleural indentation. The Harrell concordance index values were 0.869 in the training cohort (95% confidence interval: 0.837–0.901) and 0.847 in the validation cohort (95% confidence interval: 0.792–0.902). The Hosmer-Lemeshow test revealed good calibration in each of the training and validation cohorts. Decision curve analysis confirmed that the nomogram was clinically useful (risk threshold from 0.10 to 0.85).ConclusionPatient age, marginal spiculation, significant enhancement, and pleural indentation are independent predictors of malignancy in small indeterminate solid SPNs. The developed nomogram is easy-to-use and may allow the accurate prediction of malignancy in small indeterminate solid SPNs among Chinese patients.

First Human Use of a New Robotic-Assisted Fiber Optic Sensing Navigation System for Small Peripheral Pulmonary Nodules

Background: We tested a new, investigational robotic-assisted bronchoscope system with a remotely controlled catheter to access small peripheral bronchi with real-time driving under live visualization and distal tip articulation of the catheter. The unique catheter remains stationary once located at the biopsy position. Objectives: The primary objectives of this study were to evaluate the safety and feasibility of a new shape-sensing robotic bronchoscope system to bronchoscopically approach and facilitate the sampling of small peripheral pulmonary nodules of 1–3 cm. Secondary objectives included evaluating procedural characteristics and early performance trends associated with the use of the new robotic bronchoscope system. Methods: Subjects were enrolled according to study eligibility criteria at a single center. Navigation pathways were semi-automatically created using pre-procedure CT scans. Simultaneous (real-time) viewing of actual and virtual bronchi was used real time during navigation to the displayed target. An endobronchial ultrasound mini-probe was used to confirm lesion location. Flexible 19- to 23-G needles specifically designed to accommodate tight bend radii in transbronchial needle aspiration were used along with conventional biopsy tools. Enrolled subjects completed follow-up visits up to 6 months after the procedure. Results: The study included 29 subjects with a mean lesion size of 12.2 ± 4.2, 12.3 ± 3.3, and 11.7 ± 4.1 mm in the axial, coronal, and sagittal planes, respectively. The CT bronchus sign was absent in 41.4% of cases. In 96.6% of cases, the target was reached, and samples were obtained. No device-related adverse events and no instances of pneumothorax or excessive bleeding were observed during the procedure. Early performance trends demonstrated an overall diagnostic yield of 79.3% and a diagnostic yield for malignancy of 88%. Conclusion: This new robotic-assisted bronchoscope system safely navigated to very small peripheral airways under continuous visualization, and through maintenance of a static position, it provides a unique sampling capability for the biopsy of small solitary pulmonary nodules.

Methylation of RUNX3 and RASSF1A and the risk of Malignancy in small solitary pulmonary nodules.

This study aimed to evaluate the methylation of RUNX3 and RASSF1A gene promoter regions as a marker to distinguish between benign and malignant of small solitary pulmonary nodule (SPN) ≤10 mm in size. A total of 147 patients with pathologically confirmed SPNs were enrolled. DNA samples were extracted from biopsy tissues or serum. Methylation of RUNX3 and RASSF1A gene promoter regions was detected by the methylation-specific polymerase chain reaction. The expression of RUNX3 and RASSF1A in SPN tissues was detected by western blot. Of the 147 patients, 89 had benign SPNs and 58 had malignant SPNs. The rate of serum RUNX3 and RASSF1A gene methylation in malignant SPNs was significantly higher than that in benign SPNs (65.5% vs. 12.3%, and 67.2% vs. 10.1%, respectively; P < 0.05). The expression of RUNX3 and RASSF1A in malignant SPN tissues was lower than that in benign SPN tissues. The hypermethylation status of RUNX3 or RASSF1A genes was not significantly associated with age, gender, and smoking. The methylation level of the RUNX3 and RASSF1A gene promoter regions is a promising marker for assessing SPNs.

A comparison of efficacy and safety of preoperative versus intraoperative computed tomography-guided thoracoscopic lung resection

BackgroundThe efficacy and safety of intraoperative computed tomography (IOCT)-guided lung tumor localization and resection performed in a hybrid operating room (OR) compared with the conventional 2-stage preoperative CT (POCT)-guided approach for the treatment of small and deep solitary pulmonary nodules (SPNs) remains unknown. MethodsWe compared IOCT-guided (IOCT group) and POCT-guided (POCT group) thoracoscopic resections in 64 consecutive patients with SPNs. The main outcome measures included efficacy, safety, and radiation exposure. ResultsThe IOCT (n = 34) and POCT (n = 30) groups had a similar SPN depth-to-size ratio. All SPNs were successfully localized and removed using a minimally invasive approach. There were no significant intergroup differences in localization procedural time (mean, 17.68 [IOCT] vs 19.63 minutes [POCT]; P = .257) and radiation exposure (median, 3.65 [IOCT] vs 6.88 mSv [POCT]; P = .506). The use of a hybrid operating room (OR) for tumor localization significantly reduced the patient time at risk (ie, the interval from completion of localization to skin incision; mean, 215.83 [POCT] vs 13.06 minutes [IOCT]; P < .001). However, the IOCT-guided approach significantly increased the time under general anesthesia (mean, 120.61 [POCT] vs 163.1 minutes [IOCT]; P < .001) and the total OR utilization time (mean, 168.68 [POCT] vs 227.41 minutes [IOCT]; P < .001). ConclusionsCompared with the POCT-guided approach, the IOCT-guided approach decreased the time at risk, despite a significant increase in the global OR utilization time. Because no significant outcome differences were evident, the choice between the 2 approaches should be based on the most readily available approach at a surgeon's specific facility.

Cutaneous aspergillosis in a boy with acute leukemia: the lessons from a “simple” case

Fungal infections are among the most serious infectious complications in immunosuppressed patients. Primary cutaneous aspergillosis is a relatively rare manifestation and is usually described in patients with underlying malignant hematological diseases, AIDS, allogenic stem cell transplantation, solid organ transplantation, etc. We present a clinical case of a 12-year-old boy with acute lymphoblastic leukemia initially diagnosed as primary cutaneous aspergillosis caused by Aspergillus flavus . The retrospective analysis demonstrates that a small solitary pulmonary nodule could be a possible portal of entry. This means that we could consider the disease as an early stage invasive aspergillosis, which is successfully treated with voriconazole.

Learning curve of image-guided video-assisted thoracoscopic surgery for small pulmonary nodules: A prospective analysis of 30 initial patients

ObjectivesThe use of image-guided video-assisted thoracoscopic surgery for simultaneous localization and removal of small solitary pulmonary nodules in a hybrid operation room using C-arm cone-beam computed tomography is gaining momentum. We sought to assess the effect of the learning curve on procedural parameters and clinical outcomes of image-guided video-assisted thoracoscopic surgery for treating patients with small solitary pulmonary nodules. MethodsClinical variables and treatment outcomes of the 30 initial patients with solitary pulmonary nodules who were treated with image-guided video-assisted thoracoscopic surgery at Chang Gung Memorial Hospital (Taiwan) were prospectively analyzed. Two sequential groups (groups I and II, n = 15 each) were compared with regard to localization time, radiation doses, and success rates. We used the Pearson's correlation coefficient to investigate the association between the surgical experience and the procedural time. ResultsIn the entire cohort, the median size of solitary pulmonary nodules on preoperative computed tomography images was 6 mm (interquartile range, 4.5-9 mm), and their median distance from the pleural surface was 10 mm (interquartile range, 5-15 mm). The median tumor depth-to-size ratio was 1.4 (interquartile range, 0.7-2.5). The clinical parameters were similar between the 2 groups. There was an inverse association between the surgical experience and the procedural time (Pearson's r = −0.6873; P < .001). A significant reduction in localization time (median, 24 vs 49 minutes, respectively; P < .001) and radiation exposure (median, 70.7 vs 224 mGy, respectively; P < .001) was noted in group II (late patients) compared with group I (early patients). Notably, the success rates in groups II and I were similar (93.3% vs 86.7%, respectively; P = . 876). ConclusionsOur data demonstrate a significant learning curve for image-guided video-assisted thoracoscopic surgery in the treatment of solitary pulmonary nodules as evidenced by decreased localization time and radiation exposure occurring with increased surgical experience.

P2.16-025 Accuracy of Multidisciplinary Evaluation of Small Solitary Pulmonary Nodules in a Portuguese Private Hospital

P2.16-025 Accuracy of Multidisciplinary Evaluation of Small Solitary Pulmonary Nodules in a Portuguese Private Hospital

P1.16-016 Comparing Safety and Effectiveness of Image-Guided VATS Versus Conventional VATS for Small or Deep Pulmonary Nodules

Video-assisted thoracic surgery (VATS) is currently performed to diagnose and treat solitary pulmonary nodules (SPN). However, the intra-operative identification of small and/or deep nodules can be challenging with VATS as the lung is difficult to palpate. Single-stage image-guided VATS(iVATS) performed in a hybrid operation room has been introduced in recent years for the simultaneous localization and removal of small SPN. However, its efficacy and safety compared with traditional workflow has not been studied. Patients with undiagnosed SPN who required tumor localization prior to surgical resection between 2017/3 to 2017/6 were retrospectively reviewed. Based on the type of tumor localization method, patients were divided into two groups ( Group1 : iVATS ; Group 2: preoperative computed tomography guide tumor localization followed by VATS). The efficacy in localizing the tumor, complications, necessity to convert VATS to thoracotomy and radiation dose were compared. The cohort comprised 24 patients (12 in each group). The median SPN diameter was 7 mm (range: 3 – 11 mm) and the median distance of the lesion from the pleural surface was 13 mm (range: 0 – 47 mm) with no intergroup difference (P>0.05). Tumor localization procedure was successful in all patients with similar procedure time ( group1: 28 mins[range: 16∼41 mins] ; group2: 20 mins[range:14-35 mins] , p>0.05). However, the time interval from completion of localization to surgery was significantly longer in group 2 (median: 159 mins [range:78∼313mins]) than in group1(median:10mins[range:3∼20 mins], p<0.001). In group 2, migration of the hook wire occurred in 1 patients during the waiting period although it did not affect the success of VATS resection (nodule location guided by the lung puncture site). The mean effective radiation dose for group1 was 11.53 mSv and that for group2 was 13.50 mSv, respectively (P>0.05). Compared with the traditional workflow (based on preoperative CT-guided lesion localization followed by its surgical removal), single-stage iVATS for simultaneous localization and removal of small SPN is equally safe and accurate but more efficient.

Single-stage localization and removal of small lung nodules through image-guided video-assisted thoracoscopic surgery.

This case series illustrates the feasibility of single-stage image-guided video-assisted thoracoscopic surgery for simultaneous localization and removal of small solitary pulmonary nodules (SPNs). The procedure was performed in a hybrid operating room using C-arm cone-beam computed tomography equipped with a laser-guided navigation system. Between October 2016 and January 2017, 12 consecutive patients presenting with SPNs underwent image-guided video-assisted thoracoscopic surgery. The feasibility and safety of the procedure were assessed through a retrospective review of the patients' clinical charts. The median size of SPNs was 5.5 mm [interquartile range (IQR) 4-6 mm], whereas their median distance from the pleural surface was 11.7 mm (IQR 6-11.3 mm). All of the lesions were visible on intraoperative C-arm cone-beam computed tomography images, and localization was successful in 10 patients; thereafter, complete thoracoscopic resection was successfully performed. The median time required for the localization of SPNs was 45.5 min (IQR 36-60 min), whereas the median radiation exposure (expressed through the skin absorbed dose) was 223.2 mGy (IQR 180.3-321.3 mGy). Lesion localization was unsuccessful in 2 cases because to the development of pneumothorax induced by needle puncture. In such cases, a utility thoracotomy was required for the identification of SPNs. There was no operative mortality, and the median length of postoperative stay was 4 days (IQR 3.8-4 days). The results of our case series support the feasibility of image-guided video-assisted thoracoscopic surgery for detection and removal of SPNs. Future efforts should be tailored to decrease localization time and minimize radiation exposure.

Technique of skeletal navigation for localizing solitary pulmonary nodules.

We herein detail a novel method of skeletal navigation for localizing small solitary pulmonary nodules of 8-30 mm size and at a distance of less than 15 mm from visceral pleura. Thirty-four lesions found in 29 patients were successfully localized. All 34 target nodules first underwent wedge resections, and there were no cases of technical failure of the present method. This technique incurs no additional cost and complications as caused by other localization approaches. Additionally, this approach provides a backup method in cases of mark displacement.

Location techniques of pulmonary lesions during video-assisted thoracic surgery: a perspective

We read with interest the article by Bertolaccini et al. describing the use of radioactive injections to identify small solitary pulmonary nodules or impalpable ground glass opacities (GGO) during video-assisted thoracic surgery (VATS) surgery (1). The advocates of localization methods for these lesions have described over the years different techniques in thoracic surgery, most of them derived from their uses in other organs and specialties.

LROC Investigation of Three Strategies for Reducing the Impact of Respiratory Motion on the Detection of Solitary Pulmonary Nodules in SPECT.

The objective of this investigation was to determine the effectiveness of three motion reducing strategies in diminishing the degrading impact of respiratory motion on the detection of small solitary pulmonary nodules (SPN) in single photon emission computed tomographic (SPECT) imaging in comparison to a standard clinical acquisition and the ideal case of imaging in the absence of respiratory motion. To do this non-uniform rational B-spline cardiac-torso (NCAT) phantoms based on human-volunteer CT studies were generated spanning the respiratory cycle for a normal background distribution of Tc-99m NeoTect. Similarly, spherical phantoms of 1.0 cm diameter were generated to model small SPN for each of 150 uniquely located sites within the lungs whose respiratory motion was based on the motion of normal structures in the volunteer CT studies. The SIMIND Monte Carlo program was used to produce SPECT projection data from these. Normal and single-lesion containing SPECT projection sets with a clinically realistic Poisson noise level were created for the cases of: 1) the end-expiration (EE) frame with all counts, 2) respiration-averaged motion with all counts, 3) one-fourth of the 32 frames centered around EE (Quarter-Binning), 4) one-half of the 32 frames centered around EE (Half-Binning), and 5) eight temporally binned frames spanning the respiratory cycle. Each of the sets of combined projection data were reconstructed with RBI-EM with system spatial-resolution compensation (RC). Based on the known motion for each of the 150 different lesions, the reconstructed volumes of respiratory bins were shifted so as to superimpose the locations of the SPN onto that in the first bin (Reconstruct and Shift). Five human-observers performed localization receiver operating characteristics (LROC) studies of SPN detection. The observer results were analyzed for statistical significance differences in SPN detection accuracy among the three correction strategies, the standard acquisition, and the ideal case of the absence of respiratory motion. Our human-observer LROC determined that Quarter-Binning and Half-Binning strategies resulted in SPN detection accuracy statistically significantly below (P < 0.05) that of standard clinical acquisition, whereas the Reconstruct and Shift strategy resulted in a detection accuracy not statistically significantly different from that of the ideal case. This investigation demonstrates that tumor detection based on acquisitions associated with less than all the counts which could potentially be employed may result in poorer detection despite limiting the motion of the lesion. The Reconstruct and Shift method results in tumor detection that is equivalent to ideal motion correction.

Modeling the respiratory motion of solitary pulmonary nodules and determining the impact of respiratory motion on their detection in SPECT imaging.

The objectives of this investigation were to model the respiratory motion of solitary pulmonary nodules (SPN) and then use this model to determine the impact of respiratory motion on the localization and detection of small SPN in SPECT imaging for four reconstruction strategies. The respiratory motion of SPN was based on that of normal anatomic structures in the lungs determined from breath-held CT images of a volunteer acquired at two different stages of respiration. End-expiration (EE) and time-averaged (Frame Av) non-uniform-B-spline cardiac torso (NCAT) digital-anthropomorphic phantoms were created using this information for respiratory motion within the lungs. SPN were represented as 1 cm diameter spheres which underwent linear motion during respiration between the EE and end-inspiration (EI) time points. The SIMIND Monte Carlo program was used to produce SPECT projection data simulating Tc-99m depreotide (NeoTect) imaging. The projections were reconstructed using 1) no correction (NC), 2) attenuation correction (AC), 3) resolution compensation (RC), and 4) attenuation correction, scatter correction, and resolution compensation (AC_SC_RC). A human-observer localization receiver operating characteristics (LROC) study was then performed to determine the difference in localization and detection accuracy with and without the presence of respiratory motion. The LROC comparison determined that respiratory motion degrades tumor detection for all four reconstruction strategies, thus correction for SPN motion would be expected to improve detection accuracy. The inclusion of RC in reconstruction improved detection accuracy for both EE and Frame Av over NC and AC. Also the magnitude of the impact of motion was least for AC_SC_RC.

Diagnostic Performance of 18F-Fluorodeoxyglucose in 162 Small Pulmonary Nodules Incidentally Detected in Subjects Without a History of Malignancy

Solitary pulmonary nodule (SPN) still represents a diagnostic challenge. The aim of our study was to evaluate the diagnostic performance of (18)F-fluorodeoxyglucose positron emission tomography-computed tomography in one of the largest samples of small SPNs, incidentally detected in subjects without a history of malignancy (nonscreening population) and undetermined at computed tomography. One-hundred and sixty-two small (>0.8 to 1.5 cm) and, for comparison, 206 large nodules (>1.5 to 3 cm) were retrospectively evaluated. Diagnostic performance of (18)F-fluorodeoxyglucose visual analysis, receiver-operating characteristic (ROC) analysis for maximum standardized uptake value (SUVmax), and Bayesian analysis were assessed using histology or radiological follow-up as a golden standard. In 162 small nodules, (18)F-fluorodeoxyglucose visual and ROC analyses (SUVmax = 1.3) provided 72.6% and 77.4% sensitivity and 88.0% and 82.0% specificity, respectively. The prevalence of malignancy was 38%; Bayesian analysis provided 78.8% positive and 16.0% negative posttest probabilities of malignancy. In 206 large nodules (18)F-fluorodeoxyglucose visual and ROC analyses (SUVmax = 1.9) provided 89.5% and 85.1% sensitivity and 70.8% and 79.2% specificity, respectively. The prevalence of malignancy was 65%; Bayesian analysis provided 85.0% positive and 21.6% negative posttest probabilities of malignancy. In both groups, malignant nodules had a significant higher SUVmax (p < 0.0001) than benign nodules. Only in the small group, malignant nodules were significantly larger (p = 0.0054) than benign ones. (18)F-fluorodeoxyglucose can be clinically relevant to rule in and rule out malignancy in undetermined small SPNs, incidentally detected in nonscreening population with intermediate pretest probability of malignancy, as well as in larger ones. Visual analysis can be considered an optimal diagnostic criterion, adequately detecting a wide range of malignant nodules with different metabolic activity.