Characterization Of Pulmonary Lesions Research Articles

Ainda a COVID-19 em Pediatria: Radiografia de Tórax no Hospital Pediátrico de Coimbra

Nos casos confirmados e sintomáticos de COVID-19 em doentes pediátricos, a radiografia de tórax tem um papel importante na caracterização de lesões pulmonares, nomeadamente das suas dimensões, densidade e padrão. No presente estudo, observaram-se as alterações em oito radiografias de tórax realizadas a doentes COVID-19 positivos no Serviço de Urgência do Hospital Pediátrico de Coimbra (HPC). As imagens apresentaram alterações compatíveis com as descritas em outros artigos publicados, sendo o espessamento peribrônquico bilateral e as opacidades dispersas bilaterais em vidro despolido os achados mais frequentes.

Fluorine 18-FDG PET/CT and Diffusion-weighted MRI for Malignant versus Benign Pulmonary Lesions: A Meta-Analysis.

Purpose To perform a meta-analysis of the literature to compare the diagnostic performance of fluorine 18 fluorodeoxyglucose PET/CT and diffusion-weighted (DW) MRI in the differentiation of malignant and benign pulmonary nodules and masses. Materials and Methods Published English-language studies on the diagnostic accuracy of PET/CT and/or DW MRI in the characterization of pulmonary lesions were searched in relevant databases through December 2017. The primary focus was on studies in which joint DW MRI and PET/CT were performed in the entire study population, to reduce interstudy heterogeneity. For DW MRI, lesion-to-spinal cord signal intensity ratio and apparent diffusion coefficient were evaluated; for PET/CT, maximum standard uptake value was evaluated. The pooled sensitivities, specificities, diagnostic odds ratios, and areas under the receiver operating characteristic curve (AUCs) for PET/CT and DW MRI were determined along with 95% confidence intervals (CIs). Results Thirty-seven studies met the inclusion criteria, with a total of 4224 participants and 4463 lesions (3090 malignant lesions [69.2%]). In the primary analysis of joint DW MRI and PET/CT studies (n = 6), DW MRI had a pooled sensitivity and specificity of 83% (95% CI: 75%, 89%) and 91% (95% CI: 80%, 96%), respectively, compared with 78% (95% CI: 70%, 84%) (P = .01 vs DW MRI) and 81% (95% CI: 72%, 88%) (P = .056 vs DW MRI) for PET/CT. DW MRI yielded an AUC of 0.93 (95% CI: 0.90, 0.95), versus 0.86 (95% CI: 0.83, 0.89) for PET/CT (P = .001). The diagnostic odds ratio of DW MRI (50 [95% CI: 19, 132]) was superior to that of PET/CT (15 [95% CI: 7, 32]) (P = .006). Conclusion The diagnostic performance of diffusion-weighted MRI is comparable or superior to that of fluorine 18 fluorodeoxyglucose PET/CT in the differentiation of malignant and benign pulmonary lesions. © RSNA, 2018 Online supplemental material is available for this article. See also the editorial by Schiebler in this issue.

PET/MR Imaging in the Detection and Characterization of Pulmonary Lesions: Technical and Diagnostic Evaluation in Comparison to PET/CT

Fully integrated PET/MR imaging holds great promise as a novel hybrid imaging modality in oncology and might offer advantages to PET/CT in many instances, especially because of the superior soft-tissue contrast of MR imaging, compared with CT. However, lung metastases are a frequent finding in oncologic patients, and for imaging of the lung CT is still the modality of choice. Thus, we prospectively evaluated differences in quality, detection rate, size, and radiotracer uptake of pulmonary lesions in (18)F-FDG PET/CT and PET/MR imaging. Institutional review board approval and informed consent were obtained. Forty patients (23 men, 17 women; mean age ± SD, 53.2 ± 13.1 y) underwent a single-injection dual-imaging protocol with (18)F-FDG PET/CT and PET/MR imaging. Pulse sequences for the lung included T1-weighted VIBE (volumetric interpolated breath-hold examination) Dixon for attenuation correction and contrast-enhanced VIBE pulse sequences. All patients underwent a diagnostic CT of the chest in deep inspiration, which also served as a standard of reference. Two masked readers assessed in consensus all images randomly concerning quality, detection, standardized uptake value (SUV), and size of pulmonary nodules. Correlations were performed using linear correlation. Overall, 47 pulmonary lesions (mean size ± SD, 10.0 ± 11.4 mm; range, 2-60 mm) in 25 of 40 patients were detected. The PET datasets of PET/MR imaging and PET/CT revealed 22 of 47 pulmonary lesions with focal (18)F-FDG uptake. SUVs of lung lesions in PET/MR imaging and PET/CT correlated significantly (R = 0.9; P = 0.0001) and showed no significant difference (mean SUV PET/MR imaging, 6.3; PET/CT, 5.1; P = 0.388). There was a significantly lower image quality comparing Dixon and VIBE sequence with CT whereas PET from PET/CT and PET from PET/MR imaging showed the same results (2.8). Dixon images detected 15 of 47 lung lesions whereas VIBE images detected 32 of 47 lesions, respectively. The detection rates for small lung lesions less than 1 cm in diameter (n = 33) of MR imaging was significantly lower, with a detection rate of 9 of 33 for the Dixon sequence and 15 of 33 for the VIBE sequence (P < 0.0001 for VIBE and Dixon sequence). There was a high correlation of pulmonary lesion size of CT versus VIBE (R = 0.97). PET image quality and detection rate of (18)F-FDG-positive lung lesions in PET/MR imaging is equivalent to PET/CT despite differences in attenuation-correction techniques. Additionally, a high linear correlation coefficient in the SUVs for the PET images from PET/CT and PET/MR imaging was found. The detection rate of lung lesions can be significantly improved by adding a diagnostic contrast-enhanced VIBE sequence to the PET/MR imaging protocol. However, the detection rate of small lung lesions is still inferior, compared with PET/CT with diagnostic CT of the chest.

Pilot Study of the Utility of the Synthetic PET Amino-Acid Radiotracer Anti-1-Amino-3-[18F]Fluorocyclobutane-1-Carboxylic Acid for the Noninvasive Imaging of Pulmonary Lesions

Anti-1-amino-3-[(18)F]fluorocyclobutane-1-carboxylic acid (anti-3-[(18)F]FACBC) is a synthetic amino acid positron emission tomography (PET) radiotracer with utility in detection of prostate carcinoma and brain tumors and has also been shown to have uptake in lung tumor cell lines. The purpose of this study is to determine the uptake characteristics of anti-3-[(18)F]FACBC in lung carcinoma and if this radiotracer may help characterize pulmonary lesions. Ten patients with pulmonary lesions scheduled for surgical resection or biopsy underwent 45-min dynamic PET-CT imaging of the thorax after IV injection of 214.6-384.8MBq of anti-3-[(18)F]FACBC. Anti-3-[(18)F]FACBC uptake was compared with that of routine 2-deoxy-2-[(18)F]fluoro-D-glucose ([(18)F]FDG) PET-CT scans of the same patient and validated with a combination of pathology, imaging and clinical follow-up. Immunohistochemistry for Ki-67 was performed on tissue samples. There were nine malignant (seven lung nodules and two mediastinal nodes), two inflammatory, and one carcinoid lesion ranging from 1 to 3.75cm. Mean(±SD) SUVmax of malignant lesions was 6.2(±2.6), 5.9(±2.7), 5.9(±3.4), and 5.7(±3.3), at 8, 16, 28, and 40min, respectively; while for inflammatory lesions at the same time points, 4.1(±0.6), 3.3(±0.9), 2.2(±0.03), and 2.3(±0.03), respectively. The carcinoid tumor had SUVmax of 2.8, 2.6, 1.5, and 0.9 at similar time points. Mean SUVmax of all malignant lesions was higher than that of inflammatory lesions for anti-3-[(18)F]FACBC, and was statistically significant at greater than 28min post-radiotracer infusion (p < 0.05). There was no significant correlation of anti-3-[(18)F]FACBC activity with Ki67, though there was a positive trend. There was a strong correlation between anti-3-[(18)F]FACBC and [(18)F]FDG uptake. Anti-3-[(18)F]FACBC uptake in malignant lesions is greater than in inflammatory lesions with a higher degree of separation of uptake on delayed imaging. More comprehensive study is required to determine the diagnostic performance of anti-3-[(18)F]FACBC in the characterization of pulmonary lesions.

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.

18F-FDG PET-CT respiratory gating in characterization of pulmonary lesions: approximation towards clinical indications

To evaluate the effect of the 18F-FDG PET-CT respiratory gating (4D) study in the correct documentation of pulmonary lesions with faint uptake in standard PET-CT. Forty-two pulmonary lesions with a low or no detectable uptake of FDG (SUV(max) < 2.5) in 3D PET-CT were prospectively evaluated in 28 patients (19 males and 9 females), mean age 66.5 years (41-81). 22 patients had neoplastic background. A conventional PET-CT (3D) total body scan was performed approximately 60 min after iv injection of a mean dose of 370 MBq. Furthermore, a 4D PET-CT (synchronized with respiratory movement) thorax study was acquired. SUV(max) was determined for each lesion in both studies. For the 4D studies, we selected the SUV(max) in respiratory period with the highest uptake ("best bin"). We calculated the SUV(max) percentage difference between 3D and 4D PET-CT (% difference = SUV(max) 4D - SUV(max) 3D/SUV(max) 3D x 100) and the relation of this value with the size and locations of the lesions. In 4D study, any lesion with SUV(max) > or = 2.5 was classified as malignant. We assessed the changes of lesion classification (from benign to malignant) applying the 4D technique. The final diagnosis was obtained by histological assessment or clinical and radiological follow-up longer than 12 months. Forty out of 42 lesions showed an increase of SUV(max) in the 4D study with respect to 3D. The mean SUV(max) in the 3D and 4D PET-CT studies were 1.33 (+/-0.59) and 2.26 (+/-0.87), respectively. The SUV(max) percentage difference mean between both techniques was 83.3% (+/-80.81).The smaller the lesion the greater was the SUV(max) percentage difference (P < 0.05). No differences were observed depending on the location of the lesion. In 40% of cases, there was a change in the final classification of lesions from benign to malignant. In the final diagnosis, 24 lesions were malignant. 4D PET-CT diagnosed correctly the 52% of them. The 4D PET-CT study permitted a better characterization of malignant lung lesions compared with the standard PET-CT, because of its higher sensitivity. 4D PET-CT is a recommendable technique in the early diagnosis of malignant lesions.

Characterization of Pulmonary Lesions with Low F-18 FDG Uptake Using Double Phase F-18 FDG PET/CT: Comparison of Visual and Quantitative Analyses

Background of the present study was to assess the usefulness of double phase positron emission tomography/computed tomography (PET/CT) to differentiate malignant from benign pulmonary lesions with low fluorine-18 fluorodeoxyglucose (F-18 FDG) uptake. Of 218 consecutive patients who underwent double phase F-18 FDG PET/CT to evaluate pulmonary lesions found on CT, we retrospectively analyzed 30 who had focal pulmonary lesions with an SUV of <2.5. All patients underwent PET/CT of the thorax at two time points: scan 1 at 60 min and scan 2 at 120 min after the intravenous injection of 2.5 MBq F-18 FDG. The F-18 FDG PET/CT images were analyzed visually and quantitatively. Of 30 evaluated nodules, 13 (43%) proved to be malignant and 17 (57%) benign. The SUVmax1 (maximal SUV of early image), SUVmax2 (maximal SUV of delayed image), %DeltaSUVmax (percent change of maximal SUV), CR1 (contrast ratio of early image), and CR2 (contrast ratio of delayed image) of malignant pulmonary lesion were significantly higher than those of benign. However, %DeltaCR (percent change of contrast ratio) revealed no statistical differences. Among the quantitative indices, SUVmax1, SUVmax2, and CR2 were superior to the visual analysis for differentiation of malignant from benign pulmonary lesions. The SUVmax1, SUVmax2, and %DeltaSUVmax were superior to %DeltaCR for differentiation of malignant from benign pulmonary lesions. Based on the presented results, the quantitative indices except %DeltaCR were higher in malignant nodules than benign pulmonary nodules. However, the diagnostic performances were similar between visual and quantitative analyses. Further studies are needed to confirm these results and improve statistical accuracy. Key words: F-18 FDG, PET/CT, double phase, SUV.

Comparative evaluation of 99mTc-depreotide and 201Tl chloride single photon emission tomography in the characterization of pulmonary lesions

To compare (99m)Tc-depreotide and (201)Tl chloride SPET in the characterization of pulmonary lesions. Fifty-seven pulmonary lesions from 33 patients suspected of malignancy in computed tomography, were assessed by (99m)Tc-depreotide and (201)Tl early and delayed SPET imaging. Images were visually assessed and the tumour-to-normal (T/N) lung activity ratio for early (ER) and delayed (DR) scans and the retention index (RI), were calculated in every lesion. A final diagnosis was reached for all lesions, based either on histology or prolonged clinical and radiological follow-up. Twenty-three lesions were characterized as malignant and 34 benign. In visual analysis, all malignant lesions accumulated both tracers resulting in sensitivity and negative predictive values of 100%. However, false positive interpretations resulted in a specificity of 64.7% and 67.6% for (99m)Tc-depreotide and (201)Tl, respectively. ER and DR of both agents and the RI of (99m)Tc-depreotide were significantly higher in malignant, compared to benign lesions. In defining thresholds of abnormality from ROC analysis, a significant increase in specificity was observed for both tracers in both scan phases (91.2% for all), as compared to visual analysis (P<0.01). There was no significant difference in the diagnostic performance between (99m)Tc-depreotide DR and (201)Tl DR, although the former provided the highest T/N ratio. This study demonstrates that (99m)Tc-depreotide and (201)Tl SPET are equally effective and may be useful in the non-invasive determination of lung malignancy. The specificity of both techniques is significantly improved by quantifying radiopharmaceutical accumulation in pulmonary lesions.