Approach to imaging of Solitary pulmonary nodule .pptx

Approach to imaging of Solitary pulmonary nodule

1. Solitary Pulmonary Nodule Dr. Shailesh rathee JR-1 Radiodiagnosis

2. Definition of pulmonary nodule ? Diagnostic techniques Chest radiograph Primary modality; although many SPN are depicted at CT, some are still initially seen at chest radiograph Low dose CT (LDCT) Screening test HRCT Most important investigation for suspected nodule Combined PET-CT Investigation of choice Biopsy Gold standard USG For associated abnormality in pleura CECT To see the vascularity of the lesion Dual energy CT For differentiation of calcification from enhancing tissue by subtraction of iodine component Contrast Enhanced Dynamic MRI Aids in differentiating benign vs malignant SPN and asses tumor vascularity (Micro vessel count) Thallium SPECT Diagnostic accuracy for pulmonary nodules over 2 cm in size is almost same in SPECT and FDG-PET A lung nodule is a rounded or irregular opacity , which may be well or poorly defined , measuring <3 cm in diameter , surrounded by aerated lung on radio imaging . - Micro Nodule: <3 mm - Lung mass: >3 cm Guidelines: 1) American college of chest physicians clinical practice guidelines: Clinical practice consensus guidelines for Asia . 2) The Fleischner society guidelines for management of Pulmonary nodule. Types of Lung nodule: 1. Solitary : A nodule must be completely surrounded by normal lung parenchyma, without associated atelectasis, enlargement of the hilum, or pleural effusion. 2. Multiple: Sarcoidosis, HP, Silicosis ,tuberculosis, metastasis, infections, fungal/viral, multiple vascular malformation.

3. Classification of Pulmonary nodule Solid component: The part of the nodule that obscure the underlying bronco vascular structure. Ground Glass component: Opacification that is greater than that of the background but through which the underlying vascular structure is visible. Solid nodule: (Most common) Characterised by homogenous soft tissue attenuation . Ground glass nodule: Non-uniform in appearance with hazy increase in local attenuation of lung parenchyma. Part solid nodule (PSN): A focal opacity that has both solid and ground glass component < 3cm diameter. Pure ground glass (PGGN): A focal ground glass opacity < 3 cm diameter that does not obscure vascular pattern.

4. Attenuation of the lesion Solid Partially solid Ground glass

5. - 95% patients who are found to have an incidental SPN are asymptomatic. - History obtained to help rule out malignant SPN: Smoking status, previous malignancies, personal and family history of lung cancer, COPD, emphysema and interstitial lung disease. - Travel history: Endemic tuberculosis - History of autoimmune disease: Rheumatoid arthritis, granulomatosis with polyangitis . History and risk factor Lung cancer in an 80-year-old man with a 45-pack-years smoking history and occupational exposure to asbestos. Unenhanced CT image of the chest shows a right upper lobe mass with a lobular contour (arrow) and calcified pleural plaques in the left hemithorax (arrowheads). In the clinical management of an SPN, estimating the probability for malignancy is important.

6. - Continuous thin section of 1.0-1.5mm -For differentiation of Solid vs Sub-solid nodule, Fat/calcium content. Measurement: Lung window (Axial plane) If the maximal nodule dimensions are visible in the coronal or sagittal plane, measurement should be obtained on those images. HRCT technique and measurement

7. Lung nodule : Imaging approach Primary determinant of lung cancer risk: Morphology(size) Lung nodules are approached based on their: 1. True / Pseudo nodule : Always exclude an artefact & sub-cutaneous pathology as an cause of SPN. 2. Location of nodule 3. Morphology of the lesion : Size, shape, margins, edge of the lesion 4. Internal characteristic: Central necrosis, Prescence of calcification (favors benignity unless pleura calcified in which case asbestoses exposure must be excluded), fat , cavitation, cystic, air bronchogram, air crescent, air-fluid 5. Distribution & surrounding lung of pulmonary nodule: Satellite nodules, feeding vessel, positive bronchus sign 6. Temporal evolution: - Increase in size/ stability - After an SPN is initially detected, reassessing with CT at 3 months is important to determine its persistence, because lesions that results from infectious or non-infectious inflammatory causes may regress or resolve in the interval. - If a nodule is diffusely calcified or demonstrates a stable size for more than 2 years at comparison with prior radiograph, it has a high likelihood of being benign , and no further assessment is recommended.

8. Features of Malignant nodule

9. Morphology of the nodule and surrounding lung

10. Nipple shadow Pleural based lesions Chest wall lesions Skin nodules Artifacts due to clothing Screen artifacts Benign granuloma and primary bronchogenic carcinomas account for 80% of cases of SPN. Pseudonodule: Spurious lesions on CXR

11. Pseudonodule: Always exclude an artefact as a cause of SPN Pseudonodule in a 50-year-old man. (a) Close-up posteroanterior radiograph of the right lung shows a smoothly marginated nodular area of increased opacity projecting over the lung (arrow). Note the adjacent electrocardiographic lead attachment pad (arrowhead). On a follow-up radiograph obtained after removal of the attachment pad (not shown), no nodule was observed. (b) Front and back views of the electrocardiographic lead attachment pad show an eccentrically located silver nitrate pad, which explains the contiguous nodular area of increased opacity on the chest radiograph.

12. Pseudonodule: Always exclude an artefact as a cause of SPN Pseudonodule in a 61-year-old man. Bone island in a 61-year-old man with melanoma.  Close-up posteroanterior radiograph of the upper chest shows a focal area of increased opacity overlying the right seventh rib posteriorly (arrow). 2. Fluoroscopic images show a well-marginated intraosseous lesion (arrow). This finding is consistent with a bone island and obviated further investigation.

13. Always exclude a subcutaneous pathology as a cause of SPN Cutaneous nodules in a 51-year-old man with neurofibromatosis and prostatic adenocarcinoma. (a) Posteroanterior radiograph shows numerous well-marginated nodular areas of increased opacity projecting over the lower aspect of the thorax and a poorly marginated nodule overlying the upper aspect of the left hemithorax (arrow). Because the location of the upper nodule was uncertain, CT was performed. (b) CT scan helps confirm the intraparenchymal location of the nodule in the left upper lobe. (c) CT scan demonstrates multiple cutaneous nodules.

14. Location of the lesion & tumors Central tumors: Small cell carcinoma, Squamous cell carcinoma Peripheral tumors: Adeno carcinoma, Large cell carcinoma Metastasis usually basal and subpleural Benign lesion are equally distributed throughout the lung.

15. Size less than 9mm : Difficult to appreciate on CXR but readily seen on CT. As diameter of nodule increases, so does likelihood of malignancy; however a small nodule diameter does not exclude malignancy. Small nodule (4mm) have a less than 1% chance of being a primary lung cancer , even in people who smoke, whereas the risk for malignancy increases 10-20% for nodule range 8mm. Size of the lesion

16. Typically volume growth is assessed by volume doubling time, nodule volume calculated by 4pie r 3 . 1 VDT = 26% increase in the diameter of the nodule. Doubling occurring in less than 100 days likely malignant lesion. Malignant solid volume doubling time ,20 days have an infectious or inflammatory cause, whereas those with a volume doubling time > 400 days are usually benign. This growth characteristic does not apply to subsolid adenocarcinoma, which may take up to 1346 days to double in volume. Absence of growth over at least 2 yrs period : reliable Indicator of benignity. Growth rate assessment Doubling time Pathology Less than 1 month Infection, Infraction, Lymphoma, Mets of testicular tumor and sarcomas 1-18 month Bronchial carcinoma More than 18 month Granuloma, Hamartoma, Bronchial carcinoid 7.3 months Adenocarcinoma 4.1 month Undifferentiated 4.2 month Squamous cell carcinoma More than 3 years Broncho alveolar carcinoma (BAC)

17. Imaging evaluation of SPN due to infection GGN in a 66-year-old man with leukaemia (infectious etiology) who presented with fever. (likely fungal infection) Coned-down CT image shows a ground-glass opacity (arrow) in the left lower lobe. Follow-up CT image obtained 3 months later shows resolution of the ground-glass opacity. For subsolid lesions, initial follow-up CT is at 3 months to determine persistence, because lesions that result from infect or inflammatory causes may resolve in the interval.

18. B enign nodules: - Well-defined margins, smooth/round/oval contour. (Scars/areas of atelectasis may appear linear or angular) Lobulation occurs in 25% of benign nodules. However, benign conditions that result from infection or inflammation, including lipoid pneumonia, focal atelectasis, tuberculoma, and primary myelofibrosis, may also have a spiculated margin. M alignant nodules: - S piculated/lobular/irregular/notched. (Radial extension of tumour cells along lymphatics, small airways or blood vessels) - Edge: Metastasis and carcinoid tumours have sharp, smooth edges. - 21% of well defined nodules are malignant. - Spiculation attributed to growth of malignant cells along the pulmonary interstitium, lobulation due to differential growth rates within nodules. - S pecifically, a spiculated margin (described as sunburst or corona radiata sign) is highly predictive of malignancy, with PPV of 90%. In addition, a smooth margin does not exclude malignancy; many pulmonary metastases and as many as 20% of primary lung malignancies have smooth margins. Evaluation of margin of a pulmonary nodule

19. Margins of nodules Smooth margin Lobulated contour Spiculated and irregular margin

20. Margins of nodules Irregular margins in BAC Lobulated margins

21. Margins of nodules Corona radiata/corona maligna : Presence of spiculation associated with a nodule or a mass: fine, linear strands extending outward due to fibrosis surround ding the tumor/desmoplastic reaction. Pleural tail: Carcinoma have a thin linear opacity extending from the edge of a lung nodule to pleural surface: due to fibrosis. Can be seen in benign lesion too

22. Margins of nodule: Primary cancer as a cause of SPN Non-small cell lung cancer in a 63-year-old woman. Close-up chest CT scan of the right lung shows a lobulated and spiculated nodule in the lower lobe.

23. Primary cancer as a spiculated mass with central necrosis. Non-small cell lung cancer in a 61-year-old woman. Close-up chest CT scan of the right lung shows a spiculated nodule with eccentric cavitation in the upper lobe.

24. Primary cancer as a spiculated mass with central necrosis Axial CT image at the level of the right lung base demonstrates a spiculated right lower lobe nodule with a peripheral cavity. (b) Corresponding 18-F FDG PET/fused PET CT image(metabolic activity) demonstrates intense FDG uptake in the nodule in keeping with bronchogenic carcinoma.

25. SPN due to Fungal infection Ct shows multiple perihilar consolidations with necrosis and pleural effusion; guided aspirate ; aspergillus fumigatus ; this is semi invasive fungal infection Varity.

26. Primary cancer as spiculated mass with central necrosis Angio invasive Aspergillus infection in a 48 year old man with leukemia. Close –up chest CT scan of the right lung shows a thin-walled cavitatory nodule

27. SPN due to fungal infection Figure a-g thoracic, PNS CECT, 32 years male, uncontrolled diabetes, cough, fever, pleuritic pain, 2 weeks. Chest radiograph (a), shows peripherally located opacity, right mid zone. CECT mediastinal window ( b,c ), shows pre and para tracheal lymph nodes, sub-pleural mass in right lung. Lung windows ( d,e ), show bronchiectatic traction towards spiculated mass in right middle lobe. Para nasal sinuses ( f,g ) show hyerdense masses, bone erosion. Appearances suggest mucormycosis , Confirmed by guided aspirate from subpleural mass.

28. Solitary metastases as a cause of SPN Solitary metastasis from bladder cancer in a 45-year-old woman. Chest CT scan shows a smoothly marginated , 1-cm peripheral nodule. Metastatic disease was confirmed at resection. Solitary metastases account for 3%-5% of all resected solitary pulmonary nodules D/d : Slow growing primary adenocarcinoma of lung

29. Imaging evaluation of solitary lung nodule- Hamartoma 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.

30. Benign pattern of calcification: Homogenous/uniform/diffuse/solid Dense central/bulls eye Concentric rings/laminated/target : Tb, fungal granuloma Popcorn: Hamartomas, cartilage tumors Malignant pattern of calcification: Dystrophic(In areas of necrosis) Diffuse/Amorphous Psammomatous (metastasis from mucin secreating tumous such as colon, ovarian cancer) Central calcification in spiculated SPN Stippled/Punctate (due to engulfment of previous calcified lesion) Eccentric dense: Carcinoids, metastatic osteosarcoma, chondrosarcoma Pattern of calcification within lesion

31. Pattern of calcification within lesion Diffuse Central Popcorn Eccentric

32. Pattern of calcification within lesion: Benign Central Calcification Diffuse, solid: Granuloma

33. Pattern of calcification within lesion: Benign Concentric/target Popcorn calcification

34. Pattern of calcification within lesion: Malignant Eccentric dense calcification in right lower lobe carcinoid Amorphous calcification in non- small cell ca lung

35. Pattern of calcification within lesion Benign pattern of calcification in granuloma in a patient from the Ohio River valley. The CT image shows a central, or "bull's-eye," area of calcification (arrow) that is highly suggestive of granulomatous infection. The nodule is a result of Histoplasma capsulatum infection.

36. Fat: Presence of intranodular fat in nodule D/D for intramodular fat in nodule: Hamartoma Lipoid pneumonia Metastatic liposarcoma Hamartoma

37. Lesion with wall thickness: < 4mm – Likely benign >16mm – Likely malignant 4-16mm – Indeterminate Irregular: Likely malignant Thin smooth: Likely benign Psuedocavitation: Desmoplastic reaction to the tumor distorts the airway causing narrowing and/or irregularity of the small bronchi in relation to the tumor Seen as cystic glandular spaces within the mass. Cavitation Benign cavitation Malignant cavitation

38. Cystic lesion with suspicious features Suspicious features of cystic lesions: Endophytic nodule, Exophytic nodule and asymmetric wall thickening

39. Cystic lesion with suspicious features Solid pulmonary nodule with microcysts, that are likely secondary to a check-valve mechanism

40. Cystic lesion with suspicious features

41. Cystic lesion with suspicious features

42. The halo sign a poorly defined rim of ground-glass attenuation around the nodule—may represent haemorrhage, tumour infiltration, or peri nodular inflammation Seen in leukemic patients with invasive aspergillosis due to haemorrhage , BAC due to lepidic spread of tumour, wegners granulomatosis, tuberculoma, Kaposi sarcoma and lung mets . C onversely, reverse halo sign or atoll sign or bird nest which was first described in cryptogenic organizing pneumonia may also be seen in patients with lung ca after radiofrequency ablation. Surrounding lung of pulmonary nodules

43. Measurement of subsolid nodule 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, more likely the lesion is invasive adenocarcinoma.

44. Reverse halo sign and the pulmonary nodule Reverse halo sign (Solid in periphery GGO in centre) 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) Contrast-enhanced 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 RFA.

45. Air crescent sign Aspergilloma Blood clot in a cyst Complicated hydatid disease Ca arising in a cyst Rasmussen aneurysm Mucus plug in cystic bronchiectasis

46. Satellite nodules Small nodules adjacent to larger nodule or mass Predictor of benign disease like granulomatous diseases Galaxy sign : Satellite nodules in sarcoidosis Presence of satellite nodules in lung tumors is considered as locally advanced tumor.

47. Feeding vessel sign Small pulmonary artery leading directly to nodule Seen in AVF, Hematogenous metastasis , infarct

48. Positive bronchus sign A pulmonary lesion that directly abuts, narrow or occludes bronchial lumen is more likely to be malignant Also seen in tuberculoma, pulmonary infarcts, inflammatory masses This sign helps in weather transbronchial or trans thoracic biopsy helps in histological diagnosis

49. Sub solid nodules

50. Atypical adenomatous hyperplasia (AAH) pure ground Glass attenuation less than 1 cm. Adenocarcinoma in situ, pure ground glass attenuation less than 3cm. Invasive Adenocarcinoma Minimally invasive adenocarcinoma (MIA)

51. Pure ground glass nodule  In general, persistent pure GGNs that are 5 mm or smaller are believed to represent foci of atypical adenomatous hyperplasia , which is recognized as a preinvasive lung adenocarcinoma lesion.  It is known that the growth rate of GGNs and subsolid nodules is slower than that of solid lesions, with a mean volume doubling time longer than 1100 days and a mean period of 3.6 years for the appearance of a solid component.(long term follow up required)  Follow-up of GGNs nodules should be based on the identification of suspicious features such as spiculation and fissure distortion.  Owing to the slow growth rate, imaging follow-up on an annual basis is no longer indicated for GGNs smaller than 6 mm.  For GGNs that are smaller than 6 mm and have suspicious features, an initial follow-up examination at 2 years and another follow-up at 4 years are indicated.

52. Fissure retraction is a suspicious feature that warrants follow up. New small solid perifissural component and progressive retraction of the fissure are suspicious for malignancy.

53. Part solid nodule • Part-solid nodules have a solid component but also have a > 50% ground-glass appearance . When more solid components are visible on a CT scan, there is a greater propensity for invasive features. • Small partly solid nodules are frequently due to transient infections and resolve spontaneously. Persistent partly solid nodules with a solid component smaller than 6 mm typically are adenocarcinomas in situ or minimally invasive adenocarcinomas. Both of these lesions have a 100% disease-specific survival rate when they are completely resected; thus, a conservative approach and management are justified.  The solid component of a partly solid lesion is indicative of an invasive component . Progressive growth of the solid component beyond 5 mm increases the risk of invasiveness and metastasis . Thus, the more aggressive approach for partly solid lesions with a 6-mm or larger solid component is justified. • The interval growth of the solid component is highly suspicious for malignancy.

54. Change in morphology of nodule Partly solid nodule with increasing density of the solid component . Persistent solid nodules are highly suspicious for malignancy; the solid component specifically is suspicious for invasiveness

55. Perifissural nodules Perifissural nodules (PFNs) are well-circumscribed, smoothly marginated nodules in contact with or closely related to a fissure. PFNs are most commonly triangular or oval, often show a septal attachment, and are usually located below the level of the carina. At 7½-year follow-up, no PF had developed into a lung cancer; this led to conclude that PFNs have a low likelihood of changing to malignancies, indicating the potential to avoid unnecessary follow-up or invasive investigations.

56. Perifissural nodules Perifissural nodule with the classic features of an intrapulmonary lymph node. Association with the fissure and a triangular or lentiform morphology are characteristic features.  When perifissural nodules demonstrate a triangular or lentiform morphology, smooth contours, and sharp margins, they are known to represent intrapulmonary lymph nodes and are considered to be benign.  This guideline is applicable even if the average lesion dimension exceeds 6 mm and the nodules demonstrate interval.  Coronal and sagittal reconstructions are helpful for characterizing perifissural nodules and depicting the classic morphologic features and characteristic thin septal extension to the pleura. If a nodule adjacent to the pleura or a fissure demonstrates a round morphology or contour irregularity and/ or the adjacent fissure is abnormal ( ie , retracted, bowed, or transgressed), follow-up CT at 6-12 months is indicated. These features are not reassuring in the case of an intrapulmonary lymph node, and stability should be demonstrated at interval imaging follow-up.

57. Perifissural nodules Spiculation Fissural Transgression Fissural Distortion Juxtafissural location Perifissural nodule with suspicious features that warrant follow-up

58. Contrast enhancement: Nodule enhancement < 15 HU : S/o Benign lesion Nodule enhancement > 15 HU : S/o Malignant lesion 15 min delay Malignant nodules : Wash-in of >25 HU Washout of 5-31 HU Benign nodule: Wash in of < 25 HU Wash in of >25 HU in combination with a washout of >31 HU Wash in of >25 HU and persistent enhancement without washout False negative: Central necrosis Mucin producing tumors Contrast Enhancement

59. The vascular supply of most malignant pulmonary nodules is from the bronchial arterial system. Washout in malignant nodules takes place via the bronchial veins. In washout phase from the interstitial space, a near absence or substantial reduction of lymphatic flow is noted in malignant nodules. The retarded flow in the intravascular and interstitial spaces accounts for the retention of contrast medium in malignant nodules. In benign nodules, the outflow of contrast medium washout) through the intravascular space in inflammatory processes takes place through relatively straight vessels with normal configuration and washout of contrast medium from the interstital space is accelerated by active lymphatic flow. Persistent enhancement is seen in some cases due to abundant degree of fibrosis as contrast remains in fibrotic portion for long time. Contrast Enhancement

60. Contrast Enhancement Net enhancement of >25HU Washout of 5-31 HU

61. Molecular imaging of Pulmonary nodule 58-year-old man, with solid oval nodule of the apical segment of right upper lobe (area bounded by ends of red lines) without significant FDG uptake. Diagnosis of benign pulmonary nodule was reached because sequential FDG PET/CT scans remained negative during 3 years of follow-up. 55-year-old man with solid lung nodule with spiculated margin in right upper lobe that shows high FDG uptake (maximum standardized uptake value,4.9), found to be bronchial adenocarcinoma after resection.

62. Thallium SPECT in SPN

63. Fleischner Society recommendations for follow up and management of nodules detected incidentally at non-screening CT

64. American college of chest physicians clinical practice guidelines: Clinical practice consensus guidelines for Asia .

65. American college of chest physicians clinical practice guidelines: Clinical practice consensus guidelines for Asia .

66. Currently available diagnostic technique for pulmonary nodule

67. Some common benign SPN : Granuloma Commonest are Tuberculomas Single, 1-3 cm in diameter, well defined, smooth, regular outline Commonest location close to pleural surface Calcification - laminar, fleck like ,concentric, Cavitation - rare Satellite lesions sometimes seen Commonly seen in upper lobes

68. Some common benign SPN: Pulmonary Hamartoma Benign pulmonary mass containing connective tissue, cartilage , fat, smooth muscle, marrow, and bone Most common location - periphery of the lung X ray chest - spherical lobulated, well defined nodule Popcorn like calcification Fat density within the mass is a diagnostic feature

69. Vascular malformation as a cause of SPN Multiple arteriovenous malformations in a 23-year-old woman with hereditary haemorrhagic telangiectasia. Contiguous chest CT scans reveal multiple small nodular areas of increased attenuation bilaterally with enlarged feeding and draining vessels, findings that are diagnostic for arteriovenous malformations. A chest radiograph obtained earlier (not shown) demonstrated a possible small solitary pulmonary nodule in the right lower lobe.

70. Some common benign SPN: AVM Lobulated, well- marginated nodule in the lower lobe Feeding artery(arrow) and an enlarged draining vein (arrowhead) X ray - well circumscribed lesion with lobulated outline Xray/CT - Feeding vessels and draining vein can be seen It can be confirmed on CT PULMONARY ANGIOGRAPHY RARELY INDICATED

71. Some common benign SPN: AVM Nidus of malformation Pulmonary angiogram helps confirm arteriovenous malformation. Note the early draining vein (arrows)

72. Some common benign SPN: Round Pneumonia Inflammatory pseudotumour Some times pneumonic consolidation assumes a shape And density similar to pulmonary neoplasm Careful study reveals irregular margin and air bronchogram Common in children May persists after recovery from infection

73. Some common benign SPN: Infarct & Vanishing tumor Poorly marginated nodule peripherally in lower lobe likely Infarct Vanishing tumor: Sharply marginated collection of pleural fluid contained either within an interlobar pulmonary fissure or in a subpleural location adjacent to a fissure Can occur on minor fissure, oblique fissure Most of them are < 4 cms

74. Typical triad: Well-defined, round lobulated, lesion At the bifurcation Eccentric calcification Some common benign SPN: Bronchial Carcinoid Nodule with eccentric calcifications (arrow) obstructing the posterior segmental bronchus of the right upper lobe. High-resolution CT scan shows a well-defined, round, partially endobronchial nodule (arrow) in the lateral subsegmental branch of the anterior segmental bronchus of the left upper lobe.

75. FOLDED LUNG Chronic atelectasis that resembles mass X ray and ct - Peripherally located, wedge shaped opacity Based against focally thickened pleura , commonly at lung base Crow feet / comet tail of vessels sweeping into the margin of this opacity A rapidly forming pleural effusion produces an adjacent area of passive atelectasis A groove of visceral pleura may infold into the area of atelectasis and come to surround a part of it Some common benign SPN: Round Atelectasis Conventional tomographic scan of the chest in a lateral projection shows a large subpleural mass (arrowhead) in the right lower lobe of the lung. A curvilinear opacity (arrow), the comet tail sign, arises from the inferior pole of the mass and courses toward the hilum.

76. Summary Imaging by : Xray , CT, PET-CT Etiology of a solitary pulmonary nodule : Most likely bronchogenic carcinoma D/d: Infective: Tuberculoma, Fungal ball Benign neoplasm: Hamartoma Malformation: Vascular (AVM) Clinical correlation and temporal assessment is crucial for correct diagnosis.