Seth Kligerman

Spatial-Temporal [18F]FDG-PET Features for Predicting Pathologic Response of Esophageal Cancer to Neoadjuvant Chemoradiation Therapy

PURPOSE To extract and study comprehensive spatial-temporal (18)F-labeled fluorodeoxyglucose ([(18)F]FDG) positron emission tomography (PET) features for the prediction of pathologic tumor response to neoadjuvant chemoradiation therapy (CRT) in esophageal cancer. METHODS AND MATERIALS Twenty patients with esophageal cancer were treated with trimodal therapy (CRT plus surgery) and underwent [(18)F]FDG-PET/CT scans both before (pre-CRT) and after (post-CRT) CRT. The 2 scans were rigidly registered. A tumor volume was semiautomatically delineated using a threshold standardized uptake value (SUV) of ≥2.5, followed by manual editing. Comprehensive features were extracted to characterize SUV intensity distribution, spatial patterns (texture), tumor geometry, and associated changes resulting from CRT. The usefulness of each feature in predicting pathologic tumor response to CRT was evaluated using the area under the receiver operating characteristic curve (AUC) value. RESULTS The best traditional response measure was decline in maximum SUV (SUVmax; AUC, 0.76). Two new intensity features, decline in mean SUV (SUVmean) and skewness, and 3 texture features (inertia, correlation, and cluster prominence) were found to be significant predictors with AUC values ≥0.76. According to these features, a tumor was more likely to be a responder when the SUVmean decline was larger, when there were relatively fewer voxels with higher SUV values pre-CRT, or when [(18)F]FDG uptake post-CRT was relatively homogeneous. All of the most accurate predictive features were extracted from the entire tumor rather than from the most active part of the tumor. For SUV intensity features and tumor size features, changes were more predictive than pre- or post-CRT assessment alone. CONCLUSION Spatial-temporal [(18)F]FDG-PET features were found to be useful predictors of pathologic tumor response to neoadjuvant CRT in esophageal cancer.

Nonspecific Interstitial Pneumonia: Radiologic, Clinical, and Pathologic Considerations

Nonspecific interstitial pneumonia (NSIP) has variable clinical, pathologic, and radiologic manifestations. Cellular and fibrotic NSIP are the two main histologic subtypes and differ from one another in the degree of inflammation and fibrosis. It is important to differentiate NSIP from other diffuse lung diseases, especially usual interstitial pneumonia and hypersensitivity pneumonitis, owing to differences in prognosis and treatment. At high-resolution computed tomography, the most common findings suggestive of NSIP are lower lobe peripherally predominant ground-glass opacity with reticular abnormality, traction bronchiectasis, and lower lobe volume loss. Nodules, cysts, and areas of low attenuation are uncommon and should point one toward other diagnoses. Because many cases of NSIP are associated with collagen vascular diseases, it is important to look for associated findings that may suggest an underlying collagen vascular disease. Given the difficulty clinicians, pathologists, and radiologists experience in making the diagnosis of NSIP, a group approach in which these specialists work together to reach a consensus diagnosis has the highest likelihood of achieving the correct diagnosis.

Experience with staging laparoscopy in pancreatic malignancy

BACKGROUND The role of diagnostic laparoscopy in the staging of abdominal malignancies is not well defined. METHODS We retrospectively reviewed the usefulness of diagnostic laparoscopy as a staging procedure in pancreatic malignancy. This experience between February 1988 and May 1997 involves 109 cases of suspected or proven pancreatic malignancy. All laparoscopies were performed with the patient under conscious sedation and local anesthesia in an endoscopy suite. RESULTS Of the 109 patients with pancreatic cancer, 45 (42%) had metastatic disease. The use of computed tomography (CT) alone revealed the existence of liver metastases in 10 of 109 (9%) patients, which were confirmed laparoscopically. The further use of laparoscopy identified metastases in 29 more cases: hepatic, 23; hepatic and peritoneal, 3; peritoneal and mesenteric, 1; and mesenteric, 2. CT in conjunction with laparoscopy therefore revealed metastatic liver, peritoneal, or mesenteric lesions in 39 of 109 (36%) patients with pancreatic cancer. After staging laparoscopy, 67 of 69 patients underwent laparotomy. Metastatic disease was identified at laparotomy in 6 more patients; however, only 4 of these patients had metastases to the liver whereas 2 had metastases to the peripancreatic lymph nodes. Therefore, in patients with pancreatic malignancy, the negative predictive value for the diagnosis of metastases to the liver, peritoneum or mesentery was 94% (61 of 65 patients). The positive predictive value of laparoscopy alone for the detection of metastatic disease to the liver, peritoneum, or mesentery was 88% (29 of 33 patients). Laparoscopy was successfully performed without complications in all patients with pancreatic cancer; however, one had a technically unsatisfactory examination. The overall rate of resectability after staging by imaging studies and laparoscopy was 57% (35 of 61 patients). CONCLUSIONS In patients with a negative CT for metastases, laparoscopic identification of metastases avoided unnecessary laparotomy in 29 of 99 (29%) patients with pancreatic cancer. Staging laparoscopy is indicated in all cases of pancreatic malignancy before an attempt at a surgical cure.

Staging of non-small cell lung cancer using integrated PET/CT.

1203 glucose transporters on the cell membrane. The glucose is then converted to FDG-6phosphate, which cannot be further metabolized and remains trapped in the cell. Because of greater accumulation in cancer cells, more positron emission events occur in the tumor compared with surrounding normal tissue. As hundreds of thousands of coincidence events occur, they can be statistically traced back to their origin, allowing spatial localization. Due to the relatively poor spatial resolution of PET, disease localization often can prove difficult. To circumvent this problem, CT is combined with PET to provide spatially matched morphologic and functional data. PET and CT images can be integrated using three different techniques (Table 1). Although there are advantages and disadvantages to each technique, the integrated PET/CT study using a single machine provides the best coregistration of physiologic and anatomic detail [2]. In the integrated machine, both a diagnostic CT scan and a low-dose transmission scan are obtained. The diagnostic CT scan, often obtained with the administration of contrast material, provides excellent anatomic data. By creating an attenuation correction map, the transmission CT allows for a reduction in attenuation correction artifacts. These artifacts occur because of the greater attenuation of photons originating deeper within the body or within or adjacent to dense structures, such as bone, compared with those originating from the surface of the body or within or adjacent to less dense structures. The use of the transmission CT for attenuation correction also significantly reduces the PET scanning time by up to 40% compared with a standalone PET scanner [3]. Both the diagnostic CT and the transmission CT can be fused with the PET images. Although the anatomic detail is superior in the diagnostic CT scan, the transmission CT scan provides more precise Staging of Non–Small Cell Lung Cancer Using Integrated PET/CT

Modeling Pathologic Response of Esophageal Cancer to Chemoradiation Therapy Using Spatial-Temporal 18F-FDG PET Features, Clinical Parameters, and Demographics

PURPOSE To construct predictive models using comprehensive tumor features for the evaluation of tumor response to neoadjuvant chemoradiation therapy (CRT) in patients with esophageal cancer. METHODS AND MATERIALS This study included 20 patients who underwent trimodality therapy (CRT+surgery) and underwent 18F-fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) both before and after CRT. Four groups of tumor features were examined: (1) conventional PET/CT response measures (eg, standardized uptake value [SUV]max, tumor diameter); (2) clinical parameters (eg, TNM stage, histology) and demographics; (3) spatial-temporal PET features, which characterize tumor SUV intensity distribution, spatial patterns, geometry, and associated changes resulting from CRT; and (4) all features combined. An optimal feature set was identified with recursive feature selection and cross-validations. Support vector machine (SVM) and logistic regression (LR) models were constructed for prediction of pathologic tumor response to CRT, cross-validations being used to avoid model overfitting. Prediction accuracy was assessed by area under the receiver operating characteristic curve (AUC), and precision was evaluated by confidence intervals (CIs) of AUC. RESULTS When applied to the 4 groups of tumor features, the LR model achieved AUCs (95% CI) of 0.57 (0.10), 0.73 (0.07), 0.90 (0.06), and 0.90 (0.06). The SVM model achieved AUCs (95% CI) of 0.56 (0.07), 0.60 (0.06), 0.94 (0.02), and 1.00 (no misclassifications). With the use of spatial-temporal PET features combined with conventional PET/CT measures and clinical parameters, the SVM model achieved very high accuracy (AUC 1.00) and precision (no misclassifications)-results that were significantly better than when conventional PET/CT measures or clinical parameters and demographics alone were used. For groups with many tumor features (groups 3 and 4), the SVM model achieved significantly higher accuracy than did the LR model. CONCLUSIONS The SVM model that used all features including spatial-temporal PET features accurately and precisely predicted pathologic tumor response to CRT in esophageal cancer.

A Radiologic Review of the New TNM Classification for Lung Cancer

OBJECTIVE In 2009, a new TNM staging system was published by the International Union Against Cancer and the American Joint Committee on Cancer. The new edition will encompass non-small cell lung cancer, small cell lung cancer, and bronchopulmonary carcinoids. This article will review many important changes that have been made in the revised staging system. CONCLUSION It is important that radiologists learn the new system and understand the reasons for the changes to provide more accurate clinical staging.

Epidemiology of Lung Cancer in Women: Risk Factors, Survival, and Screening

OBJECTIVE Lung cancer remains the leading cause of cancer mortality in both men and women. Tobacco use causes the vast majority of lung cancer in women but does not explain all cases, because about one in five women who develop lung cancer have never smoked. CONCLUSION Environmental exposures, genetic predisposition, hormonal factors, and viral infection may all play a role in lung cancer in women. A better understanding may provide an avenue to more effective screening, diagnosis, and therapy.

Use of a Hybrid Iterative Reconstruction Technique to Reduce Image Noise and Improve Image Quality in Obese Patients Undergoing Computed Tomographic Pulmonary Angiography

Purpose: To determine whether an iterative reconstruction (IR) technique (iDose, Philips Healthcare) can reduce image noise and improve image quality in obese patients undergoing computed tomographic pulmonary angiography (CTPA). Materials and Methods: The study was Health Insurance Portability and Accountability Act compliant and approved by our institutional review board. A total of 33 obese patients (average body mass index: 42.7) underwent CTPA studies following standard departmental protocols. The data were reconstructed with filtered back projection (FBP) and 3 iDose strengths (iDoseL1, iDoseL3, and iDoseL5) for a total of 132 studies. FBP data were collected from 33 controls (average body mass index: 22) undergoing CTPA. Regions of interest were drawn at 6 identical levels in the pulmonary artery (PA), from the main PA to a subsegmental branch, in both the control group and study groups using each algorithm. Noise and attenuation were measured at all PA levels. Three thoracic radiologists graded each study on a scale of 1 (very poor) to 5 (ideal) by 4 categories: image quality, noise, PA enhancement, and “plastic” appearance. Statistical analysis was performed using an unpaired t test, 1-way analysis of variance, and linear weighted &kgr;. Results: Compared with the control group, there was significantly higher noise with FBP, iDoseL1, and iDoseL3 algorithms (P<0.001) in the study group. There was no significant difference between the noise in the control group and iDoseL5 algorithm in the study group. Analysis within the study group showed a significant and progressive decrease in noise and increase in the contrast-to-noise ratio as the level of IR was increased (P<0.001). Compared with FBP, readers graded overall image quality as being higher using iDoseL1 (P=0.0018), iDoseL3 (P<0.001), and iDoseL5 (P<0.001). Compared with FBP, there was subjective improvement in image noise and PA enhancement with increasing levels of iDose. Conclusion: The use of an IR technique leads to qualitative and quantitative improvements in image noise and image quality in obese patients undergoing CTPA.

From the Radiologic Pathology Archives: Organization and Fibrosis as a Response to Lung Injury in Diffuse Alveolar Damage, Organizing Pneumonia, and Acute Fibrinous and Organizing Pneumonia

Organization, characterized by fibroblast proliferation, is a common and nearly universal response to lung injury whether it is focal or diffuse. Despite the vast range of injurious agents, the lungs response to injury is quite limited, with a similar pattern of reaction seen radiologically and histologically regardless of the underlying cause. Although there is a tendency to divide organization into distinct entities, the underlying injury to the alveolar epithelial basement membrane is a uniting factor in these processes. This pattern of lung injury is seen in the organizing phase of diffuse alveolar damage, organizing pneumonia (OP), acute fibrinous and organizing pneumonia, and certain types of fibrotic lung disease. In addition, although organization can heal without significant injury, in some instances it progresses to fibrosis, which can be severe. When fibrosis due to organization is present, other histologic and imaging patterns, such as those seen in nonspecific interstitial pneumonia, can develop, reflecting that fibrosis can be a sequela of organization. This article reviews the histologic and radiologic findings of organization in lung injury due to diffuse alveolar damage, OP, and acute fibrinous and organizing pneumonia and helps radiologists understand that the histologic and radiologic findings depend on the degree of injury and the subsequent healing response.

Aortic Arch Dissection: A Controversy of Classification

Aortic dissections originating in the ascending aorta and descending aorta have been classified as type A and type B dissections, respectively. However, dissections with intimal flap extension into the aortic arch between the innominate and left subclavian arteries are not accounted for adequately in the widely used Stanford classification. This gap has been the subject of controversy in the medical and surgical literature, and there is a tendency among many radiologists to categorize such arch dissections as type A lesions, thus making them an indication for surgery. However, the radiologic perspective is not supported by either standard dissection classification or current clinical management. In this special report, the origin of dissection classification and its evolution into current radiologic interpretation and surgical practice are reviewed. The cause for the widespread misconception about classification and treatment algorithms is identified. Institutional review board approval and waiver of informed consent were obtained as part of this HIPAA-compliant retrospective study to assess all aortic dissection studies performed at the University of Maryland Medical Center, Baltimore between 2010 and 2012 to determine the prevalence of arch dissections. Finally, a unified classification system that reconciles imaging interpretation and management implementation is proposed.