際際滷

際際滷Share a Scribd company logo

SPN-Imaging of Solitary Pulmonary Nodules.pptx

Download as PPTX, PDF
S
suleymanfantahun

This document discusses the imaging evaluation of solitary pulmonary nodules (SPNs). It defines SPNs as rounded or oval opacities less than 3 cm in the lung surrounded by lung parenchyma. SPNs are important to evaluate as some may be early lung cancers. Imaging modalities like CT, PET, and PET-CT are used to characterize the nodule based on size, margin, contour, calcification patterns, location, and metabolic activity. Morphologic features help determine the likelihood of malignancy. Guidelines from Fleischner Society and LUNG-RADS provide recommendations on managing and follow-up of incidental pulmonary nodules based on risk factors.

Convert to study guideBETA

Transform any presentation into a summarized study guide, highlighting the most important points and key insights.

1 of 55
Download to read offline
Imaging Evaluation of Solitary Pulmonary Nodules Presenter Suleyman Fantahun, Y-I Radiology Resident Moderator Abdi Alemayehu, MD, Assistant Professor of Radiology
Outline Definition Significant of SPN in imaging Imaging modalities Morphologic features Decision analysis Reference 4/6/2024 2
Solitary pulmonary nodule /SPN/ Focal area of increased opacity in the lung /rounded, oval/ Relatively well defined 3 cm in diameter Surrounded by lung parenchyma Without other abnormalities 4/6/2024 3
Significance of SPN How Common are they? 25% of healthy adult volunteers and 51% in lung cancer screening population Why bother studying them? SPN may be early lung cancer (mortality rate = 85%) 20-30% present as SPN. Early detection of small nodules reduce lung cancerspecific mortality 4/6/2024 4
4/6/2024 5 DDx:
Goal of imaging Establishing a diagnosis based solely on the imaging features is usually not possible. but, Radiographic features are important to determine the likelihood of malignancy. Eventually commencing Noninvasive imaging-based assessment and management of SPNs 4/6/2024 6
Imaging modalities Radiograph new: Fluoroscopy CT PET PET-CT Image guided Biopsy 4/6/2024 7
Clinical Evaluation Independent predictors of malignancy Advanced age Current or past smoking habit History of extra-thoracic cancer more than 5 years before detection of a nodule 4/6/2024 8
Cont An SPN (likelihood of metastasis) In the absence of a known prior malignancy Unlikely to be a metastasis With melanoma, sarcoma, or testicular carcinoma Malignant SPN is 2.5x likely to be metastasis than a primary lung cancer With head and neck SCC Malignant SPN is 8x likely to be a primary lung cancer 4/6/2024 9
Imaging Evaluation Steps:- Is it really SPN? Classify:- Solid nodule Sub solid nodule /SSN/ Pure Ground Glass Attenuation Nodule /GGAN/ Partly Solid nodule /PSN/ Asses the likelihood of malignancy. 4/6/2024 10
Size How to measure? Smallest diameter?, largest?, average of both . For solid nodules: 4/6/2024 11
Margin and Contour Irregular, lobulated contour with spiculated margin. Malignant (90%) 4/6/2024 12 Smooth surface contour, sharply defined edge Malignant (20%) Metastases Carcinoid tumors
Pleural tail sign Thin linear opacity extending from the edge of a nodule to the pleural surface Represents Fibrosis 4/6/2024 13 Halo sign A halo of GGO surrounding a soft tissue density lung nodule Could represent Hemorrhage, lepidic spread of tumor
Reverse Halo sign (Atoll sign) Central area of GGO surrounded by a rim of consolidation, COP, Lung cancer after radiofrequency ablation 4/6/2024 14
Air bronchograms Commonly seen in malignant nodules(29%) than in Benign(6%) 4/6/2024 15 Pseudocavitation Small rounded lucencies, not representing air bronchograms or cavitation
4/6/2024 16 Cavitation Wall thickness < 5 mm 92% benign 5 to 15 mm 49% malignant > 15 mm 95% malignant Benign lesions often have a thin, smooth wall Malignant lesions tend to have a thick, nodular wall
Air-fluid Level Indicate a benign lesion Bacterial lung abscess Uncommon in cavitary carcinoma, cavitary TB and fungal infections 4/6/2024 17 Satellite Nodules Small nodules seen adjacent to a larger nodule Predict a benign lesion Granulomatous diseases In Sarcoidosis Galaxy sign
4/6/2024 18 Calcification - Benign Patterns
4/6/2024 19 May be seen in benign SPNs but are visible in as many as 10% to 15% of cancers Indeterminate patterns
4/6/2024 20
Fat CT (40 to 120 HU) Most likely hamartoma lipoma, or lipoid pneumonia Presence in SPN is sufficient for calling it benign N.B: Follow-up is appropriate. 4/6/2024 21
Nodule Location About two thirds of lung cancers occur in the upper lobes Sixty percent of cancers Lung periphery Metastatic tumor Subpleural or outer third of the lung 2/3rd in the lower lobes TB Apical or posterior upper lobes, superior segment of the lower lobes 4/6/2024 22
Nodule Enhancement CT enhancement Only in spherical nodules with homogeneous attenuation Malignant nodules > 20 HU Benign nodules < 15 HU 4/6/2024 23
4/6/2024 24
Nodule Growth Nodules are usually spherical, nodule volume = 4r3 Assessed by volume doubling time Manifests as a 26% increase in diameter Limitations Small nodules Change in diameter is difficult to perceive Subsolid nodules Small and poorly defined, growth is difficult to perceive 4/6/2024 25
Cont Solid SPN - Volume doubling time <20 days Infectious or inflammatory < 100 days /20400 days/ Malignant >400 days Benign Stable size over a 2-year period (>730 days) is benign. NEW* = 2-mm threshold for growth 4/6/2024 26
Unusual patterns of growth Temporary regression of SPNs 4/6/2024 27
Cont Increased wall thickness 4/6/2024 28
Subsolid nodules /SSN/ Persistent subsolid nodules are more likely to be malignant. After an SSN is initially detected, reassessing with CT at 3 months. For persistent SSNs, CT features important for differentiating benign from malignant nodules: Nodule attenuation Presence and size of any solid component 4/6/2024 29
4/6/2024 30
Cont Solid component in SSN represents: Invasive component and/or Fibrosis with alveolar collapse To characterization of the degree of invasion in SSN: Mean nodule attenuation number Ratio of the solid-to-ground glass attenuation portions 4/6/2024 31
Ratio of the solid-to-ground glass attenuation portions 50% Air-containing type, Most are Adenocarcinoma in situ >50% Solid type, most are invasive adenocarcinoma 4/6/2024 32
Growth in SSN Sub solid Nodules Volume doubling of GGAN > PSN > Solid lesions Growth may manifest as: 1. Increase in size, 2. Increase in attenuation, 3. Development of a solid component 4. Increase in size of a solid component. Another method Mass of nodule (volume x density) 4/6/2024 33
4/6/2024 34
4/6/2024 35
4/6/2024 36
Nodule Metabolism FDG-PET High sensitivity and specificity in Solid nodules 10 mm Standardized uptake value (SUV) Benign Vs Malignant nodules SUV cutoff of 2.5 Visual analysis is as accurate PET/CT Be careful of Artifacts and misregistration 4/6/2024 37
4/6/2024 38
Decision Analysis: Management For nodules that are detected incidentally The Fleischner Society Guideline American College of Chest Physicians (ACCP) Screening-detected Nodules LUNG-RADS (Lung Imaging Reporting and Data System) by ACR 4/6/2024 39
4/6/2024 40
4/6/2024v 41
Updated Fleischner Society Guidelines for Managing Incidental Pulmonary Nodules Population(s) not intended 35 years Patients with Known Malignancy Immunocompromised Patients Lung Cancer Screening Population Slice selection 1.0 - 1.5mm thin Nodule in thick(>2mm) sections Follow up thin section, if size >6mm 4/6/2024 42
Risk Factors Older age Heavy smoking, Larger nodule size, Upper lobe location, and/or Nodule margin irregularity or spiculation Risk Categories Low <5% risk of cancer Intermediate 5%65% risk High >65% estimated risk 4/6/2024 43
Scenarios Single solid 68-mm nodules in low-risk patients Well-defined with benign appearance at 1218 months Discontinue follow up GGNs smaller than 6 mm Suspicious features such as spiculation and fissure distortion Follow-up examination at 2 years the 4 years. 4/6/2024 44
4/6/2024 45
Cont A decrease in size accompanied by an increase in density Warrants imaging surveillance Peri-fissural nodule Triangular or lentiform morphology, smooth contours, and sharp margins Benign Intrapulmonary lymph nodes No follow-up CT Suspicious features Follow up CT 4/6/2024 46
Suspicious features: contour spiculation (a), fissural transgression (b), fissural distortion (arrow) (c), and a juxtafissural nodule not entirely associated with the fissure (d). 4/6/2024 47
4/6/2024 48
Cystic lung lesion - could occur by: Cystification of a nodule Tumor arising from the wall of a preexisting cyst Suspicious features: Asymmetric wall thickening endophytic or exophytic mural nodule 4/6/2024 49
4/6/2024 50
4/6/2024 51
4/6/2024 52
4/6/2024 53
References 1. THORACIC IMAGING Pulmonary and Cardiovascular Radiology, Third Edition, (Page 952-1004) 2. Update in the Evaluation of the Solitary Pulmonary Nodule, RSNA, 2014 3. The Solitary Pulmonary Nodule - The NEJM, 2003 4. Guidelines for Management of Incidental Pulmonary Nodules Detected on CT Images: From the Fleischner Society 2017 5. Solitary Pulmonary Nodules. Morphologic Evaluation RSNA, 2000 6. Updated Fleischner Society Guidelines for Managing Incidental Pulmonary Nodules: Common Questions and Challenging Scenarios, RSNA, 2018 4/6/2024 54
Thank You.

More Related Content

SPN-Imaging of Solitary Pulmonary Nodules.pptx

  • 1. Imaging Evaluation of Solitary Pulmonary Nodules Presenter Suleyman Fantahun, Y-I Radiology Resident Moderator Abdi Alemayehu, MD, Assistant Professor of Radiology
  • 2. Outline Definition Significant of SPN in imaging Imaging modalities Morphologic features Decision analysis Reference 4/6/2024 2
  • 3. Solitary pulmonary nodule /SPN/ Focal area of increased opacity in the lung /rounded, oval/ Relatively well defined 3 cm in diameter Surrounded by lung parenchyma Without other abnormalities 4/6/2024 3
  • 4. Significance of SPN How Common are they? 25% of healthy adult volunteers and 51% in lung cancer screening population Why bother studying them? SPN may be early lung cancer (mortality rate = 85%) 20-30% present as SPN. Early detection of small nodules reduce lung cancerspecific mortality 4/6/2024 4
  • 6. Goal of imaging Establishing a diagnosis based solely on the imaging features is usually not possible. but, Radiographic features are important to determine the likelihood of malignancy. Eventually commencing Noninvasive imaging-based assessment and management of SPNs 4/6/2024 6
  • 7. Imaging modalities Radiograph new: Fluoroscopy CT PET PET-CT Image guided Biopsy 4/6/2024 7
  • 8. Clinical Evaluation Independent predictors of malignancy Advanced age Current or past smoking habit History of extra-thoracic cancer more than 5 years before detection of a nodule 4/6/2024 8
  • 9. Cont An SPN (likelihood of metastasis) In the absence of a known prior malignancy Unlikely to be a metastasis With melanoma, sarcoma, or testicular carcinoma Malignant SPN is 2.5x likely to be metastasis than a primary lung cancer With head and neck SCC Malignant SPN is 8x likely to be a primary lung cancer 4/6/2024 9
  • 10. Imaging Evaluation Steps:- Is it really SPN? Classify:- Solid nodule Sub solid nodule /SSN/ Pure Ground Glass Attenuation Nodule /GGAN/ Partly Solid nodule /PSN/ Asses the likelihood of malignancy. 4/6/2024 10
  • 11. Size How to measure? Smallest diameter?, largest?, average of both . For solid nodules: 4/6/2024 11
  • 12. Margin and Contour Irregular, lobulated contour with spiculated margin. Malignant (90%) 4/6/2024 12 Smooth surface contour, sharply defined edge Malignant (20%) Metastases Carcinoid tumors
  • 13. Pleural tail sign Thin linear opacity extending from the edge of a nodule to the pleural surface Represents Fibrosis 4/6/2024 13 Halo sign A halo of GGO surrounding a soft tissue density lung nodule Could represent Hemorrhage, lepidic spread of tumor
  • 14. Reverse Halo sign (Atoll sign) Central area of GGO surrounded by a rim of consolidation, COP, Lung cancer after radiofrequency ablation 4/6/2024 14
  • 15. Air bronchograms Commonly seen in malignant nodules(29%) than in Benign(6%) 4/6/2024 15 Pseudocavitation Small rounded lucencies, not representing air bronchograms or cavitation
  • 16. 4/6/2024 16 Cavitation Wall thickness < 5 mm 92% benign 5 to 15 mm 49% malignant > 15 mm 95% malignant Benign lesions often have a thin, smooth wall Malignant lesions tend to have a thick, nodular wall
  • 17. Air-fluid Level Indicate a benign lesion Bacterial lung abscess Uncommon in cavitary carcinoma, cavitary TB and fungal infections 4/6/2024 17 Satellite Nodules Small nodules seen adjacent to a larger nodule Predict a benign lesion Granulomatous diseases In Sarcoidosis Galaxy sign
  • 18. 4/6/2024 18 Calcification - Benign Patterns
  • 19. 4/6/2024 19 May be seen in benign SPNs but are visible in as many as 10% to 15% of cancers Indeterminate patterns
  • 21. Fat CT (40 to 120 HU) Most likely hamartoma lipoma, or lipoid pneumonia Presence in SPN is sufficient for calling it benign N.B: Follow-up is appropriate. 4/6/2024 21
  • 22. Nodule Location About two thirds of lung cancers occur in the upper lobes Sixty percent of cancers Lung periphery Metastatic tumor Subpleural or outer third of the lung 2/3rd in the lower lobes TB Apical or posterior upper lobes, superior segment of the lower lobes 4/6/2024 22
  • 23. Nodule Enhancement CT enhancement Only in spherical nodules with homogeneous attenuation Malignant nodules > 20 HU Benign nodules < 15 HU 4/6/2024 23
  • 25. Nodule Growth Nodules are usually spherical, nodule volume = 4r3 Assessed by volume doubling time Manifests as a 26% increase in diameter Limitations Small nodules Change in diameter is difficult to perceive Subsolid nodules Small and poorly defined, growth is difficult to perceive 4/6/2024 25
  • 26. Cont Solid SPN - Volume doubling time <20 days Infectious or inflammatory < 100 days /20400 days/ Malignant >400 days Benign Stable size over a 2-year period (>730 days) is benign. NEW* = 2-mm threshold for growth 4/6/2024 26
  • 27. Unusual patterns of growth Temporary regression of SPNs 4/6/2024 27
  • 28. Cont Increased wall thickness 4/6/2024 28
  • 29. Subsolid nodules /SSN/ Persistent subsolid nodules are more likely to be malignant. After an SSN is initially detected, reassessing with CT at 3 months. For persistent SSNs, CT features important for differentiating benign from malignant nodules: Nodule attenuation Presence and size of any solid component 4/6/2024 29
  • 31. Cont Solid component in SSN represents: Invasive component and/or Fibrosis with alveolar collapse To characterization of the degree of invasion in SSN: Mean nodule attenuation number Ratio of the solid-to-ground glass attenuation portions 4/6/2024 31
  • 32. Ratio of the solid-to-ground glass attenuation portions 50% Air-containing type, Most are Adenocarcinoma in situ >50% Solid type, most are invasive adenocarcinoma 4/6/2024 32
  • 33. Growth in SSN Sub solid Nodules Volume doubling of GGAN > PSN > Solid lesions Growth may manifest as: 1. Increase in size, 2. Increase in attenuation, 3. Development of a solid component 4. Increase in size of a solid component. Another method Mass of nodule (volume x density) 4/6/2024 33
  • 37. Nodule Metabolism FDG-PET High sensitivity and specificity in Solid nodules 10 mm Standardized uptake value (SUV) Benign Vs Malignant nodules SUV cutoff of 2.5 Visual analysis is as accurate PET/CT Be careful of Artifacts and misregistration 4/6/2024 37
  • 39. Decision Analysis: Management For nodules that are detected incidentally The Fleischner Society Guideline American College of Chest Physicians (ACCP) Screening-detected Nodules LUNG-RADS (Lung Imaging Reporting and Data System) by ACR 4/6/2024 39
  • 42. Updated Fleischner Society Guidelines for Managing Incidental Pulmonary Nodules Population(s) not intended 35 years Patients with Known Malignancy Immunocompromised Patients Lung Cancer Screening Population Slice selection 1.0 - 1.5mm thin Nodule in thick(>2mm) sections Follow up thin section, if size >6mm 4/6/2024 42
  • 43. Risk Factors Older age Heavy smoking, Larger nodule size, Upper lobe location, and/or Nodule margin irregularity or spiculation Risk Categories Low <5% risk of cancer Intermediate 5%65% risk High >65% estimated risk 4/6/2024 43
  • 44. Scenarios Single solid 68-mm nodules in low-risk patients Well-defined with benign appearance at 1218 months Discontinue follow up GGNs smaller than 6 mm Suspicious features such as spiculation and fissure distortion Follow-up examination at 2 years the 4 years. 4/6/2024 44
  • 46. Cont A decrease in size accompanied by an increase in density Warrants imaging surveillance Peri-fissural nodule Triangular or lentiform morphology, smooth contours, and sharp margins Benign Intrapulmonary lymph nodes No follow-up CT Suspicious features Follow up CT 4/6/2024 46
  • 47. Suspicious features: contour spiculation (a), fissural transgression (b), fissural distortion (arrow) (c), and a juxtafissural nodule not entirely associated with the fissure (d). 4/6/2024 47
  • 49. Cystic lung lesion - could occur by: Cystification of a nodule Tumor arising from the wall of a preexisting cyst Suspicious features: Asymmetric wall thickening endophytic or exophytic mural nodule 4/6/2024 49
  • 54. References 1. THORACIC IMAGING Pulmonary and Cardiovascular Radiology, Third Edition, (Page 952-1004) 2. Update in the Evaluation of the Solitary Pulmonary Nodule, RSNA, 2014 3. The Solitary Pulmonary Nodule - The NEJM, 2003 4. Guidelines for Management of Incidental Pulmonary Nodules Detected on CT Images: From the Fleischner Society 2017 5. Solitary Pulmonary Nodules. Morphologic Evaluation RSNA, 2000 6. Updated Fleischner Society Guidelines for Managing Incidental Pulmonary Nodules: Common Questions and Challenging Scenarios, RSNA, 2018 4/6/2024 54

Editor's Notes

  • #4: SPN is a discrete, well-marginated, rounded opacity less than or equal to 3 cm in diameter that is completely surrounded by lung parenchyma, does not touch the hilum or mediastinum, and is not associated with adenopathy, atelectasis, or pleural effusion.
  • #12: The smaller the nodule the more likely it is benign.
  • #13: Adenocarcinoma Hamartoma Metastasis from head and neck SCC
  • #14: Adenocarcinoma. HRCT shows an irregular, spiculated nodule with multiple pleural tails. Air bronchograms are visible within the nodule Halo sign in invasive aspergillosis Halo sign in adenocarcinoma. HRCT shows a dense central nodule surrounded by a halo (arrows). In adenocarcinoma, the dense center usually represents invasive growth, while the halo represents the presence of lepidic tumor growth.
  • #15: Figure 2. Reverse halo sign after radiofrequency ablation of a pulmonary metastasis in a 63-year-old man with pancreatic cancer who previously underwent left upper lobectomy. (a) Contrast-enhanced CT image shows a left-lower-lobe metastasis (arrow). (b) Contrastenhanced CT image obtained 1 month after radiofrequency ablation shows the treated metastasis (arrow), which now has mixed attenuation, surrounded by a ground-glass opacity (*) and a well-circumscribed rim of consolidation (arrowheads), a finding known as the reverse halo sign. Originally described in cryptogenic organizing pneumonia, the reverse halo, or atoll, sign can also be seen in paracoccidioidomycosis, tuberculosis, lymphomatoid granulomatosis, Wegener granulomatosis, sarcoidosis, and tumors after radiofrequency ablation
  • #16: 1. Adenocarcinoma. HRCT shows an irregular, spiculated nodule with multiple pleural tails. Air bronchograms are visible within the nodule. 2. Adenocarcinoma with a spiculated margin seen on CT. Two pleural tails (arrows) extend to the pleural surface. This appearance has been termed corona radiata or corona maligna. The surface of the nodule is lobulated and shows notches, both of which are findings indicating malignancy. Several lucencies within the nodule represent air bronchograms of areas of pseudocavitation, typical findings in adenocarcinoma and BAC.
  • #17: Thin-walled lung cavities. A: In a patient with a persisting lung cavity from Coccidioides immitis infection, the wall is thin and smooth, measuring less than 5 mm in thickness. Cavitary adenocarcinoma shown on HRCT in six contiguous scans. The nodule contains an irregular cavity; is irregular and lobulated in shape, notched, and spiculated; and is associated with pleural tails. It also contains several air bronchograms.
  • #18: Cavitary squamous cell carcinoma shown at two levels. The wall of the cavity is irregular, with several thick nodular regions (white arrow). The cavity contains an air-fluid level (black arrows). This is uncommon in malignancy and may represent hemorrhage or infection. 1. Tuberculosis. A right upper lobe nodule is associated with satellites (arrows). This appearance is most typical of a benign process but sometimes is seen with carcinoma.
  • #19: Homogeneous calcification. Dense and uniform calcification (B) of a small right upper lobe nodule (arrow, A) is typical of a benign lesion, usually a tuberculoma. Dense central or bulls-eye calcification in a hamartoma. A round lung nodule (arrows) adjacent to the descending aorta shows dense central calcification. This is typical of histoplasmoma or hamartoma. Concentric or target calcification (arrow). One or more rings of calcium may be seen. This pattern is typical of a histoplasmoma. Multiple confluent nodular foci of calcification (popcorn calcification; arrow) in a hamartoma. This appearance is typical of hamartoma and corresponds to the calcification of cartilage nodules.
  • #20: Eccentric calcification in an adenocarcinoma. A lobulated mass shows a small focus of eccentric calcification (arrow).
  • #21: Carcinoid tumor with stippled calcifications. A: A sharply marginated lung mass is visible. B: CT shows a sharply marginated, lobulated mass with multiple small foci of calcification.
  • #22: Figure 3. Hamartoma in a 72-year-old woman with an unknown primary malignancy that metastasized to the liver. Contrast-enhanced CT image shows a well-circumscribed left-lower-lobe nodule (arrow) with low attenuation (-46 HU), a finding consistent with fat. Focal fat can also be seen in a pulmonary nodule in liposarcoma metastases and lipoid pneumonia.
  • #25: CT enhancement study in a 54-year-old woman with endometrial hyperplasia. CT images obtained before (a) and after (b) administration of intravenous contrast material show the nodule has enhanced, with an increase in attenuation values of 109 HU. Typically, malignant nodules enhance with an increase in attenuation values of more than 20 HU, whereas benign nodules enhance with an increase in attenuation values of less than 15 HU. Results from transthoracic needle aspiration biopsy revealed carcinoid tumor
  • #28: Transient decrease in size of a lung cancer. (a) CT image obtained at the patients initial presentation shows a nodule (arrow) in the left lower lobe. (b) Follow-up CT image obtained 1 year later shows the nodule (arrow), which decreased in size. (c) CT image obtained 2 years after the initial presentation shows the nodule (arrow), which increased in size and lobularity. Although most lung cancers grow at a steady rate, temporary regression and growth can occur. It is postulated that a transient decrease in size may be related to the development of a fibrous component and/or collapse of fibrosis. Accordingly, a decrease in size requires continued imaging reassessment to confirm long-term stability or resolution.
  • #29: Lung cancer manifesting with increased wall thickness of a cystic airspace in a 77-year-old man with a history of right upper lobectomy for adenocarcinoma. (a) Contrast-enhanced CT image shows a cystic airspace (*) in the right lower lobe. (b) Follow-up CT image obtained 6 months later shows a new soft-tissue component (arrows) along the wall of the cystic airspace. Results of histologic analysis of the soft-tissue component revealed adenocarcinoma. The finding of an isolated cystic airspace with increased wall thickness should raise the suspicion for lung cancer
  • #31: Figure 7. IASLC, ATS, and ERS classification of lung adenocarcinoma, in which preinvasive lesions include atypical adenomatous hyperplasia (AAH) and adenocarcinoma in situ (AIS), both of which are defined as lesions with purely lepidic growth along the alveolar surface. (a) CT image shows an AAH lesion (arrow), which typically has pure ground-glass attenuation and measures less than 1 cm. However, lesions larger than 1 cm have been reported. (b) CT image shows an AIS lesion (arrowheads), which typically has pure groundglass attenuation and measures less than 3 cm. Invasive lesions include minimally invasive adenocarcinoma (MIA) and invasive adenocarcinoma, which are further classified as having a lepidic, acinar, papillary, micropapillary, or solid-predominant pattern. (c) CT image shows an MIA lesion (arrow), which has a predominantly lepidic pattern; lacks necrosis; does not invade lymphatics, blood vessels, or pleura; measures less than 3 cm; and has an invasive component (arrowhead) that measures no more than 5 mm in any one location. (d) CT image shows a lepidic-predominant adenocarcinoma (LPA) in its nonmucinous form. Necrosis may be present, and the focus of invasion of lymphatics and blood vessels is greater than 5 mm.
  • #33: Fleischner Society recommendations for measuring subsolid lesions at CT. (a) CT image obtained with narrow and/or mediastinal window settings shows the solid component (*) of a subsolid lesion. (b) CT image obtained with wide and/or lung window settings shows the ground-glass-attenuation component (arrowheads) of the lesion. Measurements are based on the average of the long and short axis dimensions. Determination of the percentage of solid to ground-glass-attenuation components is important, because the greater the solid component, the more likely that the lesion is an invasive adenocarcinoma. * = solid component
  • #35: Subsolid lesion that increased in size, which indicates an increased risk for malignancy, in a 55-year-old man. (a) Coned-down contrast-enhanced CT image shows a 1.3-cm nodule (arrow) with pure ground-glass attenuation in the left lower lobe. Pulmonary vessels are visible within the lesion. The Fleischner Society recommends that solitary pure GGANs larger than 5 mm undergo initial follow-up CT in 3 months to determine persistence followed by yearly surveillance CT for a minimum of 3 years if the nodule is persistent and remains unchanged. This lesion persisted at 3-month follow-up CT. (b) Follow-up CT image obtained 3 years later shows the lesion, which increased in size to 1.8 cm. Biopsy was performed, and results of histologic analysis revealed adenocarcinoma. Because the volume-doubling time of subsolid lung cancers is typically longer than that for lung cancers that manifest as a solid nodule, imaging reassessment is recommended for an extended period of time for patients with a subsolid nodule.
  • #36: (11) Increased attenuation in a subsolid lesion, which indicates an increased risk for malignancy. (a) Coned-down CT image of the chest with coronal reformation shows a 1.2-cm subsolid nodule (arrow) in the left upper lobe. (b) Follow-up CT image obtained 1 year later shows the nodule (arrow), which demonstrates increased attenuation, in addition to an increase in the overall size. According to the American College of Chest Physicians (ACCP) algorithm, an increase in nodule attenuation should be interpreted as an indicator of possible malignancy, and, in most cases, surgical resection should be strongly considered.
  • #37: (12) Development of a soft-tissue component in a subsolid lesion, which indicates an increased risk for malignancy, in an 85-year-old man with a history of adenocarcinoma that was treated with right upper lobectomy. (a) Contrast-enhanced CT image shows a 1.8-cm nodule with pure ground-glass attenuation (arrow) in the left upper lobe. Pulmonary vessels and the air bronchogram sign are visible in the lesion. (b) Follow-up CT image obtained 3 months later shows the nodule (arrow), with a new solid component posteriorly (arrowhead). Biopsy was performed, and results of histologic analysis revealed adenocarcinoma. A direct correlation between the soft-tissue component and the degree of invasion or aggressiveness of subsolid adenocarcinomas and patient prognosis and survival has been reported
  • #38: Alternative to measuring nodule enhancement in the evaluation of solid SPNs. FDG is a measure of glucose metabolism
  • #39: Figure 18. Infection mimicking malignancy in a 30- year-old man with no symptoms and a right lower lobe mass detected at chest radiography performed for a routine occupational health examination. (a, b) Unenhanced CT (a) and PET/CT (b) images show a 3-cm solid lesion in the right lower lobe (arrow in a) with a maximum SUV of 16.7. Biopsy results revealed granulomatous inflammation and no malignant cells. (c) Followup CT image obtained 2 months later shows regression of the lesion (arrow). Infectious and inflammatory conditions can accumulate FDG and be misinterpreted as malignant. Figure 16. PET-negative neuroendocrine tumor in a 59-year-old woman. Unenhanced CT (a) and PET/CT (b) images show a well-circumscribed nodule in the middle lobe (arrow) with no FDG uptake. Results from transthoracic needle biopsy revealed a well-differentiated neuroendocrine tumor (carcinoid). False-negative PET findings can also occur in patients with indolent adenocarcinomas
  • #46: Figure 2. GGN smaller than 6 mm. (a) Axial contrast materialenhanced chest CT image (lung window) of the left lung shows a pure GGN in the lingula. There is retraction of the fissure (arrow), although it is subtle. Fissure retraction is a suspicious feature that warrants follow-up. (b) Axial nonenhanced chest CT image (lung window) obtained at 2-year follow-up shows an interval increase in the density of the nodule, with a new small solid perifissural component and progressive retraction of the fissure (arrow). These features are suspicious for malignancy
  • #49: Figures 6, 7. (6) Perifissural nodule with suspicious features that warrant follow-up. (a) Axial nonenhanced chest CT image (lung window) of the right lung shows a 5-mm solid nodule (arrow) in the right middle lobe. The nodule has irregular contours and a juxtafissural location. (b) Axial nonenhanced chest CT image (lung window) obtained at 12-month follow-up shows interval growth of the nodule (arrow), with persistent contour irregularity. The lesion was found to represent a small invasive adenocarcinoma at resection
  • #50: (10) Illustrations depict the suspicious features of cystic lesions: endophytic nodule (a), exophytic nodule (b), and asymmetric wall thickening (c).
  • #51: Figures 9, 10. (9) Cystic lung lesion with suspicious features. (a) Axial contrast-enhanced CT image (lung window) of the right lung shows a cystic lesion in the right lower lobe. There is asymmetric wall thickening and an endophytic mural nodule (arrow), features that are highly suspicious for malignancy. (b) Sagittal contrast-enhanced CT image (lung window) better shows the endophytic nodule (arrow) in the inferior wall of the suspicious right lower lobe cystic lesion.