Helical computed tomography diagnosis of pleural dissemination in lung cancer: comparison of thick-section and thin-section helical computed tomography

Thymic Imaging Pitfalls and Strategies for Optimized Diagnosis

Thymic imaging is challenging because the imaging appearance of a variety of benign and malignant thymic conditions are similar. CT is the most commonly used modality for mediastinal imaging, while MRI and fluorine 18 fluorodeoxyglucose (FDG) PET/CT are helpful when they are tailored to the correct indication. Each of these imaging modalities has limitations and technical pitfalls that may lead to an incorrect diagnosis and mismanagement. CT may not be sufficient for the characterization of cystic thymic processes and differentiation between thymic hyperplasia and thymic tumors. MRI can be used to overcome these limitations but is subject to other potential pitfalls such as an equivocal decrease in signal intensity at chemical shift imaging, size limitations, unusual signal intensity for cysts, subtraction artifacts, pseudonodularity on T2-weighted MR images, early imaging misinterpretation, flow and spatial resolution issues hampering assessment of local invasion, and the overlap of apparent diffusion coefficients between malignant and benign thymic entities. FDG PET/CT is not routinely indicated due to some overlap in FDG uptake between thymomas and benign thymic processes. However, it is useful for staging and follow-up of aggressive tumors (eg, thymic carcinoma), particularly for detection of occult metastatic disease. Pitfalls in imaging after treatment of thymic malignancies relate to technical challenges such as postthymectomy sternotomy streak metal artifacts, differentiation of postsurgical thymic bed changes from tumor recurrence, or human error with typical "blind spots" for identification of metastatic disease. Understanding these pitfalls enables appropriate selection of imaging modalities, improves diagnostic accuracy, and guides patient treatment. ©RSNA, 2024 Test Your Knowledge questions for this article are available in the supplemental material.

Diaphragmatic hernia during treatment of lung cancer harboring an EGFR mutation

Epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) are a first-line treatment for patients with nonsmall-cell lung cancer harboring EGFR mutations. We report a 65-year-old Japanese woman with nonsmall-cell lung cancer taking an EGFR-TKI who visited the emergency department with acute nausea and vomiting. Imaging studies demonstrated an incarcerated diaphragmatic hernia. Urgent diagnostic surgery revealed a gap in the diaphragm acting as a hernial orifice, where a metastatic tumor was detected. We consider that regression of the diaphragmatic metastasis by EGFR-TKI therapy resulted in perforation of the diaphragm, causing the diaphragmatic hernia. Gastrointestinal adverse events, e.g. nausea, vomiting and diarrhea, are common during EGFR-TKI treatment. However, this case suggests that in patients with diaphragmatic metastasis, we should consider the rare possibility of diaphragmatic perforation and a subsequent hernia.

Pleural staging using local anesthetic thoracoscopy in dry pleural dissemination and minimal pleural effusion

BACKGROUND

Dry pleural dissemination (DPD) and minimal (<10 mm thick) pleural effusion (PE) may be discovered intraoperatively as unexpected metastases. A definitive diagnostic procedure such as pleural biopsy is rarely attempted in such patients preoperatively. We retrospectively investigated the use and safety of local anesthetic thoracoscopy (LAT) as a pleural staging tool in the diagnosis of DPD and minimal PE.

METHODS

We reviewed 18 patients with non-small cell lung cancer (radiological DPD and minimal PE in 13 and five patients, respectively) who underwent LAT using a flex-rigid pleuroscope for pleural staging from April 2015 to September 2020.

RESULTS

The median age of the patients was 72 years. Nine patients (50%) were men. The dominant histological type was adenocarcinoma (n = 16). Three patients each with radiological DPD and minimal PE had visible PE on the LAT. Pleural biopsy was performed in the 16 cases in which pleural abnormalities were identified. On pleural staging, five cases were diagnosed without pleural dissemination (M0), and 13 cases were diagnosed with pleural dissemination (M1a). Only one case in which the lesion could not be identified because of pleural adhesions was false-negative. The success rates for pleural staging, sensitivity, specificity, positive predictive value, and negative predictive value were 94.4% (17/18), 92.8% (13/14), 100% (4/4), 100% (13/13), and 80.0% (4/5), respectively. There were no lung lacerations or other severe complications caused by the procedure or during blunt dissection.

CONCLUSION

LAT might be a useful tool for accurate pleural staging in cases with DPD and minimal PE suspected radiologically.

The Role of 18F-FDG PET/CT Integrated Imaging in Distinguishing Malignant from Benign Pleural Effusion

Objective

The aim of our study was to evaluate the role of ¹⁸F-FDG PET/CT integrated imaging in differentiating malignant from benign pleural effusion.

Methods

A total of 176 patients with pleural effusion who underwent ¹⁸F-FDG PET/CT examination to differentiate malignancy from benignancy were retrospectively researched. The images of CT imaging, ¹⁸F-FDG PET imaging and ¹⁸F-FDG PET/CT integrated imaging were visually analyzed. The suspected malignant effusion was characterized by the presence of nodular or irregular pleural thickening on CT imaging. Whereas on PET imaging, pleural ¹⁸F-FDG uptake higher than mediastinal activity was interpreted as malignant effusion. Images of ¹⁸F-FDG PET/CT integrated imaging were interpreted by combining the morphologic feature of pleura on CT imaging with the degree and form of pleural ¹⁸F-FDG uptake on PET imaging.

Results

One hundred and eight patients had malignant effusion, including 86 with pleural metastasis and 22 with pleural mesothelioma, whereas 68 patients had benign effusion. The sensitivities of CT imaging, ¹⁸F-FDG PET imaging and ¹⁸F-FDG PET/CT integrated imaging in detecting malignant effusion were 75.0%, 91.7% and 93.5%, respectively, which were 69.8%, 91.9% and 93.0% in distinguishing metastatic effusion. The sensitivity of ¹⁸F-FDG PET/CT integrated imaging in detecting malignant effusion was higher than that of CT imaging (p = 0.000). For metastatic effusion, ¹⁸F-FDG PET imaging had higher sensitivity (p = 0.000) and better diagnostic consistency with ¹⁸F-FDG PET/CT integrated imaging compared with CT imaging (Kappa = 0.917 and Kappa = 0.295, respectively). The specificities of CT imaging, ¹⁸F-FDG PET imaging and ¹⁸F-FDG PET/CT integrated imaging were 94.1%, 63.2% and 92.6% in detecting benign effusion. The specificities of CT imaging and ¹⁸F-FDG PET/CT integrated imaging were higher than that of ¹⁸F-FDG PET imaging (p = 0.000 and p = 0.000, respectively), and CT imaging had better diagnostic consistency with ¹⁸F-FDG PET/CT integrated imaging compared with ¹⁸F-FDG PET imaging (Kappa = 0.881 and Kappa = 0.240, respectively).

Conclusion

¹⁸F-FDG PET/CT integrated imaging is a more reliable modality in distinguishing malignant from benign pleural effusion than ¹⁸F-FDG PET imaging and CT imaging alone. For image interpretation of ¹⁸F-FDG PET/CT integrated imaging, the PET and CT portions play a major diagnostic role in identifying metastatic effusion and benign effusion, respectively.

Flex-rigid pleuroscopy under local anesthesia in patients with dry pleural dissemination on radiography

OBJECTIVE

Medical thoracoscopy using a flex-rigid pleuroscope under local anesthesia is a recent diagnostic procedure for malignant pleural disease. Although most previous studies have reported its usefulness, especially in wet pleural dissemination, the feasibility of flex-rigid pleuroscopy in patients with dry pleural dissemination is not well established.We assessed the diagnostic performance of flex-rigid pleuroscopy under local anesthesia in patients suspected of dry pleural dissemination on radiography.

METHODS

The pleuroscopic parameters of all patients (n = 56) who underwent flex-rigid pleuroscopy at the National Cancer Center Hospital from October 2011 to September 2013 were retrospectively reviewed. Those with computed tomography findings of asymmetric pleural thickening or pleural nodules without pleural effusion (dry group, n = 16) were compared with the remaining patients with pleural effusion (wet group).

RESULTS

The dry group consisted of eight men and eight women, with a median age of 61 years (range, 48-79 years). The definitive diagnoses were adenocarcinoma (n = 10), mesothelioma (n = 2) and chronic inflammation (n = 3). The diagnostic accuracy was 93.8% (15/16). Only two minor complications were observed: mild chest pain (n = 1) and transient hypoxia (n = 1). No major complications such as pneumothorax were observed. The mean duration of post-operative chest tube drainage in the dry group was 2.31 ± 2.26 days. Complications, operation duration and diagnostic accuracy did not statistically differ between the two groups.

CONCLUSIONS

Flex-rigid pleuroscopy under local anesthesia can be a well-tolerated diagnostic procedure for radiographic dry pleural dissemination with respect to diagnostic yield and complications.

[MSCT imaging diagnosis of peripheral lung cancer with dry pleural dissemination]

背景与目的

周围型肺癌的胸膜转移率较高，且干性胸膜转移术前容易漏诊，造成不必要的手术，因此术前诊断就尤为重要。回顾性分析伴有干性胸膜转移的周围型肺癌的多层螺旋CT（multislice spiral computed tomography, MSCT）影像，并探讨其对干性胸膜转移的诊断价值。

方法

对27例经病理或临床证实的周围型肺癌伴有干性胸膜转移的MSCT影像学表现进行回顾性分析。

结果

本组27例干性胸膜转移，CT检出率为85%，叶间胸膜转移检出率为91%，非叶间胸膜检出率为63%。27例中多发胸膜结节者26例（96%），所有胸膜结节均位于病变同侧，有叶间胸膜结节者23例，多表现为小结节，可沿叶间胸膜呈串珠样或簇状排列；有非叶间胸膜结节者8例，以大结节多见，肺-结节界面清晰；27例中胸膜增厚者15例（56%），可表现为胸膜带状增厚、不均匀增厚或两者同时存在。本组干性胸膜转移者影像学表现以混合型多见（63%）。

结论

MSCT对周围型肺癌患者干性胸膜转移有较好的诊断价值，尤其对表现为胸膜结节者有较高的准确性。

Dry pleural dissemination in non-small cell lung cancer: prognostic and diagnostic implications

PURPOSE

To compare prognostic differences between dry pleural dissemination (DPD) and wet pleural dissemination (WPD) in patients with non-small cell lung cancer (NSCLC) andto review the applicability of computed tomographic (CT) findings of DPD for rendering the diagnosis of this disease.

MATERIALS AND METHODS

The institutional review board approved this retrospective study, and informed patient consent was waived. Of 98 patients (male-to-female ratio, 55:43; mean age, 60 years ± 12) with NSCLC, 20 patients had pathologically proved DPD, and the remaining 78 patients had pathologically proved WPD. Twelve patients, who had been lost to follow-up, were excluded from survival analysis. Observers looked for CT findings of multiple pleural or fissural nodules (more than six in number) and uneven thickening or bandlike thickness. Survival after initial presentation was analyzed and compared between patients with DPD (n = 19) and patients with WPD (n = 67) by using the Kaplan-Meier method and the log-rank test. The sensitivity of CT for depicting DPD was also calculated.

RESULTS

Median survival after initial presentation was significantly longer in patients with DPD than in patients with WPD; it was 38 months (95% confidence interval [CI]: 29.9 months, 46.0 months) in patients with DPD and 13 months (95% CI: 9.8 months, 16.2 months) in patients with WPD (P <.001). CT helped identify DPD in 90% (18 of 20) of patients with pathologically proved DPD. Multiple pleural or fissural nodules were noted on CT images in 16 (80%) of 20 patients. Uneven or bandlike pleural thickening was recognized in 15 (75%) patients.

CONCLUSION

Patients with DPD show better survival than patients with WPD. CT helps suggest strongly the presence of DPD preoperatively.

PET/CT in non-small cell lung cancer staging—promises and problems

Integrated positron emission tomography/computed tomography (PET/CT) has many advantages over solitary PET and CT, which has led it to become an increasingly established imaging technique in the management of many cancers. This article will review the evidence for the role of (18)F-fluorodeoxyglucose PET/CT in non-small cell lung cancer staging, examining its strengths, weaknesses and cost-effectiveness.

CT and MRI of Lung Cancer

Computed tomography (CT) is still the cornerstone of imaging studies in the preoperative staging and post- therapeutic evaluation of lung cancer. The most recent developments in multidetector technology have dramatically improved the temporal and spatial resolution of CT. In the mean time, magnetic resonance imaging (MRI) has not become a routine examination in lung imaging and is today only used as a problem-solving tool in patients in whom CT remains equivocal. This article will describe the current tools developed in the multidetector CT era for evaluating the lung, and state-of-the-art MR examination of the chest. Then, the role of CT and MRI in nodule detection, the distinction between benign and malignant nodules, and the benefit of CT and MRI in the staging and post-therapeutic evaluation of lung cancer will be covered.

Integrated PET/CT and the Dry Pleural Dissemination of Peripheral Adenocarcinoma of the Lung

OBJECTIVE

The aim of this study was to describe retrospectively the CT findings of dry pleural dissemination of peripheral lung adenocarcinoma, and to compare the mutual roles of PET and CT components of integrated PET/CT in the diagnosis of the disease.

METHODS

The authors analyzed retrospectively the CT findings of pathologically proved dry pleural dissemination in 8 of 172 patients with peripheral adenocarcinoma of the lung. Subsequently, one radiologist and one nuclear medicine physician (unaware of the CT and pathologic results) evaluated together in a random order the integrated PET/CT of 172 adenocarcinoma patients (8 with dry pleural dissemination and 164 without). They recorded the presence of pleural dissemination using PET images only and using both PET and CT images. The diagnostic accuracies with respect to the presence of pleural dissemination were evaluated.

RESULTS

The CT findings of dry pleural dissemination were pleural small nodules (n=8, 100%) (>or=6 in number in all patients; 198/204 nodules were <5 mm in diameter and 6/204 were 5-10 mm) and uneven (n=4, 50%) or band-like (n=3, 38%) fissural thickening. By PET only, the sensitivity, specificity, and accuracy of dry pleural dissemination were 25% (2/8), 90% (147/164), and 87% (149/172), respectively; by PET plus CT these were 100% (8/8), 100% (164/164), and 100% (172/172), respectively.

CONCLUSIONS

The CT findings of dry pleural dissemination are multiple small pleural nodules and uneven pleural thickening. Dry pleural dissemination should be diagnosed using CT findings at integrated PET/CT because lesions causing pleural dissemination without pleural effusion are usually beyond PET resolution.

Subtle pleural metastasis without large effusion in lung cancer patients: preoperative detection on CT

Objective

We wanted to describe the retrospective CT features of subtle pleural metastasis without large effusion that would suggest inoperable lung cancer.

Materials and Methods

We enrolled 14 patients who had open thoracotomy attempted for lung cancer, but they were proven to be inoperable due to pleural metastasis. Our study also included 20 control patients who were proven as having no pleural metastasis. We retrospectively evaluated the nodularity and thickening of the pleura and the associated pleural effusion on the preoperative chest CT scans. We reviewed the histologic cancer types, the size, shape and location of the lung cancer and the associated mediastinal lymphadenopathy.

Results

Subtle pleural nodularity or focal thickening was noted in seven patients (50%) having pleural metastasis and also in three patients (15%) of control group who were without pleural metastasis. More than one of the pleural changes such as subtle pleural nodularity, focal thickening or effusion was identified in eight (57%) patients having pleural metastasis and also in three patients (15%) of the control group, and these findings were significantly less frequent in the control group patients than for the patients with pleural metastasis (p = 0.02). The histologic types of primary lung cancer in patients with pleural metastasis revealed as adenocarcinoma in 10 patients (71%) and squamous cell carcinoma in four patients (29%). The location, size and shape of the primary lung cancer and the associated mediastinal lymphadenopathy showed no significant correlation with pleural metastasis.

Conclusion

If any subtle pleural nodularity or thickening is found on preoperative chest CT scans of patients with lung cancer, the possibility of pleural metastasis should be considered.

Multi-detector row CT: is prospective electrocardiographic triggering improving the detection of small pulmonary tumors?

RATIONALE AND OBJECTIVES

To compare prospectively ECG-triggered multi-detector row computed tomography (ECG-MDR-CT) and multi-detector row computed tomography (MDR-CT) without triggering for the detection of pulmonary tumors.

MATERIALS AND METHODS

100 patients with proven or suspected tumors were referred for CT of the lung for staging of lung metastases. First, a non-enhanced scan was performed using prospective ECG-triggering on a four-row multidetector helical CT scanner, followed by a contrast-enhanced scan without triggering. The diagnostic assessibility in detecting intrapulmonary nodules and mediastinal structures was graded using a 5-point scale (rated 1 = bad to 5 = very good image quality).

RESULTS

ECG-MDR-CT images detected a total of 26% more pulmonary nodules than MDR-CT. For tumors <5 mm, the detection rate was 62% higher using ECG-triggered scans (P = .024). Subjective assessment found median demarcation ratings for all pulmonary findings of 4 (ECG-MDR-CT) versus 3 (MDR-CT). Mediastinal structures were delineated better using ECG triggering. The median ranking for demarcation of pulmonary findings <10 mm was 4 on ECG-MDR-CT and 3 on MDR-CT, respectively. For vessels and the left bronchus, the median of demarcation was 4 on triggered images and 2 on MDR-CT, respectively. The median values referring to the demarcation of mediastinal structures were not significantly different between ECG-MDR-CT and MDR-CT.

CONCLUSION

Our data indicate the superiority of prospectively triggered ECG-MDR-CT over MDR-CT for the diagnosis of small pulmonary tumors using a 4-row multidetector CT.

Imaging of Metastatic Disease to the Thorax

Tumor imaging is at the forefront of radiology technology and is the focus of most cutting edge research. Radiologic applications for imaging of metastases are applied to initial staging, restaging after neoadjuvant therapy, and follow-up surveillance after therapy for tumor recurrence. CT is the routine imaging choice in staging, restaging, and detection of recurrence. Fluorodeoxyglucose-positron emission tomography has evolved as an imaging modality that further improves staging as well as the detection of recurrent and metastatic disease.