Multidetector CT of Solitary Pulmonary Nodules

Ectopic papillary thyroid carcinoma mimicking distant metastatic tissue

We report a case of a 50-year-old woman presenting with a solid nodule in each lung. She was previously suspected of having lung cancer and distant pulmonary metastasis on the basis of imaging findings. Surgical pathology revealed that the left lung nodule was adenocarcinoma, but the contralateral nodule was papillary thyroid carcinoma (PTC). We subsequently performed total thyroidectomy, and the histological findings of the resected specimen showed no suspicious tumor tissue. Overall, the results led to a diagnosis of ectopic intrapulmonary PTC with synchronous lung adenocarcinoma. Ectopic intrapulmonary PTC is a rare but true phenomenon that may be easily mistaken for pulmonary metastasis in daily practice. It is important to improve the recognition of ectopic intrapulmonary thyroid tumors to avoid misdiagnosis.

Differential diagnostic value of 64-slice spiral computed tomography in solitary pulmonary nodule

The present study aimed to evaluate the diagnostic value of 64-slice spiral multivariate computed tomography (CT) combined with dynamic contrast-enhanced scanning for benign and malignant solitary pulmonary nodules (SPNs). A total of 93 patients with SPN as diagnosed by CT were included. All these patients were subjected to routine and dynamic enhancement CT scanning. After reconstruction, the morphological characteristics following dynamic enhancement were analyzed, and compared for the benign and malignant SPN cases. The incidences of lobulation, spicular sign, pleural indentation and vacuole sign in the malignant SPN group were significantly higher compared with the benign SPN group. During the dynamic enhancement scanning, the CT values at all the time points for the inflammatory and malignant SPN groups were significantly higher than the benign SPN group. No significant differences were observed in the dynamic enhancement CT values at 30, 60, 90 and 120 sec between the inflammatory, and malignant SPN groups. However, in the inflammatory SPN group, the dynamic enhancement CT values at 300 and 540 sec were significantly lower than the malignant SPN group. Notably, the diagnostic accordance rate for the morphological signs combined with dynamic enhancement diagnosis was significantly higher than the morphological signs alone. The 64-slice spiral CT morphological signs combined with dynamic enhancement detection can be more effective for the differential diagnosis of benign and malignant SPN, which may provide potent evidence for the early clinical treatment.

Use of diffusion-weighted magnetic resonance imaging to distinguish between lung cancer and focal inflammatory lesions: a comparison of intravoxel incoherent motion derived parameters and apparent diffusion coefficient

Background Using imaging techniques to diagnose malignant and inflammatory lesions in the lung can be challenging. Purpose To compare intravoxel incoherent motion (IVIM) and apparent diffusion coefficient (ADC) magnetic resonance imaging (MRI) analysis in their ability to discriminate lung cancer from focal inflammatory lung lesions. Material and Methods Thirty-eight patients with lung masses were included: 30 lung cancers and eight inflammatory lesions. Patients were imaged with 3.0T MRI diffusion weighted imaging (DWI) using 10 b values (range, 0-1000 s/mm²). Tissue diffusivity ( D), pseudo-diffusion coefficient ( D*), and perfusion fraction ( f) were calculated using segmented biexponential analysis. ADC (total) was calculated with monoexponential fitting of the DWI data. D, D*, f, and ADC were compared between lung cancer and inflammatory lung lesions. Receiver operating characteristic analysis was performed for all DWI parameters. Results The ADC was significantly higher for inflammatory lesions than for lung cancer ([1.21 ± 0.20] × 10^-3 mm²/s vs. [0.97 ± 0.15] × 10^-3 mm²/s; P = 0.004). By IVIM, f was found to be significantly higher in inflammatory lesions than lung cancer ([46.10 ± 12.92] % vs. [29.29 ± 10.89] %; P = 0.005). There was no difference in D and D* between lung cancer and inflammatory lesions ( P = 0.747 and 0.124, respectively). f showed comparable diagnostic performance with ADC in differentiating lung cancer from inflammatory lung lesions, with areas under the curve of 0.833 and 0.826, sensitivity 80.0% and 73.3%, and specificity 75.0% and 87.5%, respectively. Conclusion The IVIM parameter f value provides comparable diagnostic performance with ADC and could be used as a surrogate marker for differentiating lung cancer from inflammatory lesions.

Missed pulmonary metastasis

Objective

To assess the rate of detection of pulmonary nodules on preoperative computed tomography, based on intraoperative palpation of non-imaged pulmonary nodules, in patients who underwent thoracotomy for metastasectomy with bimanual lung palpation.

Methods

A retrospective study carried out on all cases of pulmonary metastasectomy performed in King Faisal Specialist Hospital and Research Center over a 10-year period (2001–2011). The number of nodules detected on preoperative computed tomography by a radiologist was compared with the number of nodules identified on pathology. Resected pulmonary nodules were classified to benign or malignant. Secondary outcomes were operative approach and primary malignancy.

Results

215 metastasectomies were performed by thoracotomy. The incidence of nodules that were not imaged preoperatively was 36% (41% of mesenchymal tumors, 28% of epithelial tumors).

Conclusion

Metastasectomy by an open approach, which affords bimanual palpation of the entire lung, discovered ipsilateral non-imaged malignant pulmonary metastases in 36% of cases (41% of mesenchymal tumors).

ACR appropriateness Criteria® radiographically detected solitary pulmonary nodule

The solitary pulmonary nodule (SPN) is a common medical problem for which management can be quite complex. Imaging remains at the center of management of SPNs, and computed tomography is the primary modality by which SPNs are characterized and followed up for stability. This manuscript summarizes the American College of Radiology Appropriateness Criteria for radiographically detected solitary pulmonary nodules and briefly reviews the various imaging techniques available. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed every 2 years by a multidisciplinary expert panel. The guideline development and review include an extensive analysis of current medical literature from peer reviewed journals and the application of a well-established consensus methodology (modified Delphi) to rate the appropriateness of imaging and treatment procedures by the panel. In those instances in which evidence is lacking or not definitive, expert opinion may be used to recommend imaging or treatment.

Evaluation of solitary pulmonary nodule detected during computed tomography examination

The solitary pulmonary nodule (SPN) has always been a diagnostic challenge for the radiologists. Currently, with increased utilization of computed tomography (CT) greater number of nodules is being discovered, with numerous indeterminate lesions, which frequently cannot be immediately classified into benign or malignant category.In this article we review the imaging features of benign and malignant round opacities; we demonstrate currently used standards and also more advanced techniques that are helpful in evaluating SPNs such as contrast-enhanced CT, PET/CT imaging and also pathologic sampling with biopsy or surgical resection.We also summarize the methods of evaluating and managing SPNs based on the latest guidelines from the Fleischner Society and American College of Chest Physicians.

Reversed halo sign after radiofrequency ablation of a lung nodule

We report a case of the "reversed halo sign" 6 weeks after radiofrequency ablation (RFA) of a lung neoplasm in an 80-year-old man. The "reversed halo sign," first described on computed tomography in cryptogenic organizing pneumonia, has later been described as being associated with a wide range of pulmonary pathologies, including paracoccidiodomycosis, tuberculosis, lymphomatoid granulomatosis, Wegener granulomatosis, invasive pulmonary fungal infections, and sarcoidosis. Although a number of computed tomography findings have been reported after RFA of both primary lung tumors and pulmonary metastases, this case demonstrates that the reversed halo sign may also occur after RFA.

[Effects of different reconstruction parameters on CT volumetric measurement of pulmonary nodules]

BACKGROUND AND OBJECTIVE

It has been proven that volumetric measurements could detect subtle changes in small pulmonary nodules in serial CT scans, and thus may play an important role in the follow-up of indeterminate pulmonary nodules and in differentiating malignant nodules from benign nodules. The current study aims to evaluate the effects of different reconstruction parameters on the volumetric measurements of pulmonary nodules in chest CT scans.

METHODS

Thirty subjects who underwent chest CT scan because of indeterminate pulmonary nodules in General Hospital of Tianjin Medical University from December 2009 to August 2011 were retrospectively analyzed. A total of 52 pulmonary nodules were included, and all CT data were reconstructed using three reconstruction algorithms and three slice thicknesses. The volumetric measurements of the nodules were performed using the advanced lung analysis (ALA) software. The effects of the reconstruction algorithms, slice thicknesses, and nodule diameters on the volumetric measurements were assessed using the multivariate analysis of variance for repeated measures, the correlation analysis, and the Bland-Altman method.

RESULTS

The reconstruction algorithms (F=13.6, P<0.001) and slice thicknesses (F=4.4, P=0.02) had significant effects on the measured volume of pulmonary nodules. In addition, the coefficients of variation of nine measurements were inversely related with nodule diameter (r=-0.814, P<0.001). The volume measured at the 2.5 mm slice thickness had poor agreement with the volumes measured at 1.25 mm and 0.625 mm, respectively. Moreover, the best agreement was achieved between the slice thicknesses of 1.25 mm and 0.625 mm using the bone algorithm.

CONCLUSIONS

Reconstruction algorithms and slice thicknesses have significant impacts on the volumetric measurements of lung nodules, especially for the small nodules. Therefore, the reconstruction setting in serial CT scans should be consistent in the follow-up of indeterminate pulmonary nodules, more importantly for the small nodules.

[Usefulness of chest CT in the diagnosis of pulmonary sequestration]

Pulmonary sequestration is a rare congenital anomaly, characterized by nonfunctional embryonic pulmonary tissue. Pulmonary sequestration accounts for 0.15-6.40% of all congenital pulmonary malformations. This anomaly, which is classified as intralobar or extralobar, involves the lung parenchyma and its vascularization. We report the case of a 56-year-old male presenting with hemoptysis. A chest X-ray showed an area of opacity behind the cardiac silhouette in the base of the left hemithorax. Chest CT scans with intravenous contrast revealed pulmonary sequestration. The patient underwent surgery, in which the anomalous tissue was successful resected. The postoperative evolution was favorable, and the patient was discharged to outpatient treatment.