Solitary pulmonary nodule

Imaging plays an important role in diagnosis and formulating differential diagnosis in case of Solitary pulmonary nodule. It helps in differentiating and predicting benign and malignant nodules.

1. IMAGING OF SOLITARY PULMONARY NODULE PRESENTOR : DR.NAVNI

2. DEFINITION A solitary pulmonary nodule (SPN) is a round or oval opacity smaller than 3 cm in diameter that is completely surrounded by pulmonary parenchyma and is not associated with lymphadenopathy , atelectasis , or pneumonia.

3. D/D OF SPN MALIGNANT NEOPLASMS CARCINOMA LYMPHOMA LYMPHOPROLIFERATIVE DISEASES SOLITARY METASTATIC NEOPLASM (MELANOMA,OSTEOSARCOMA,PROSTATE, COLON,BREAST,RCC,TESTICULAR CARCINOMA) BRONCHIAL CARCINOID SARCOMA

4. BENIGN NEOPLASM AND NEOPLASM LIKE CONDITION HAMARTOMA ENDOMETRIOMA MESENCHYMAL TUMOR

5. INFECTIVE CAUSES GRANULOMA MYCETOMA ASPERGILLOMA ECHINOCOCCUS/HYDATID CYST FOCAL ROUND PNEUMONIA LUNG ABSCESS

6. INFLAMMATORY RHEUMATOID NODULES SARCOIDOSIS WEGENERS GRANULOMATOSIS

7. AIRWAY AND INHALATIONAL DISEASE MUCOID IMPACTION BRONCHIAL ATRESIA CYSTIC FIBROSIS PROGRESSIVE MASSIVE FIBROSIS LIPOID PNEUMONIA

8. VASCULAR LESIONS HEMATOMA INFARCTION PULMONARY ARTERY ANEURYSM PULMONARY VEIN VARIX ARTERIOVENOUS FISTULA SEPTIC EMBOLISM

9. CONGENITAL BRONCHOGENIC CYST CCAM INTRAPULMONARY LYMPH NODE SEQUESTRATION

10. IDIOPATHIC/MISCELLANEOUS AMYLOIDOSIS FLUID FILLED BULLA ROUND ATELECTASIS

11. SPURIOUS LESIONS ON CXR 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

12. IMAGING OF SPN CHEST RADIOGRAPH CT SCAN MRI FDG-PET / SPECT

13. MORPHOLOGICAL CHARACTERISTICS OF SPN SIZE Size less than 9mm : difficult to appreciate on CXR but readily seen on CT DIAMETER MALIGNANCY RATE <1 CM 35 % 1-2 CM 50% 2-3CM 80% >3CM 97%

14. 2.SHAPE CARCINOMAS : IRREGULAR/LOBULATED/NOTCHED Lobulation occurs in 25% of benign nodules. BENIGN : ROUND/OVAL/SMOOTH (SCARS/AREAS OF ATELECTASIS MAY APPEAR LINEAR OR ANGULAR)

15. 3.LOCATION CENTRAL TUMORS : SMALL CELL CA, SQUAMOUS CELL CA PERIPHERAL TUMORS : ADENO CA, LARGE CELL CA METASTASIS USUALLY BASAL AND SUBPLEURAL BENIGN LESIONS ARE EQUALLY DISTRIBUTED THROUGHOUT THE LUNG

16. 4.EDGE MALIGNANT : IRREGULAR/SPICULATED/LOBULATED ( radial extension of the tumor cells along the lymphatics , small airways or blood vessels) BENIGN : SMOOTH/SHARP Metastases and carcinoid tumors have sharp, smooth edges 21% of well defined nodules are malignant

17. IRREGULAR MARGINS IN BAC

18. LOBULATED MARGINS

19. CORONA RADIATA/CORONA MALIGNA Presence of spiculation associated with a nodule or a mass : fine,linear strands extending outward due to fibrosis surrounding the tumor/ desmoplastic reaction

20. PLEURAL TAIL Carcinomas have a thin linear opacity extending from the edge of a lung nodule to the pleural surface : due to fibrosis Can be seen in benign lesions too

21. HALO SIGN Halo of ground glass opacity surrounding a nodule Seen in leukemic patients with invasive aspergillosis due to haemorrage , BAC due to lepidic spread of tumor, wegeners granulomatosis , tuberculoma

22. INTERNAL CHARACTERISTICS OF SPN CALCIFICATION BENIGN NODULES

23. HOMOGENOUS/UNIFORM/DIFFUSE/SOLID DENSE CENTRAL/BULLS EYE CONCENTRIC RINGS/LAMINATED/TARGET : Tb, fungal granulomas POPCORN : Hamartomas , cartilage tumors

24. CENTRAL CALCIFICATION

25. DIFFUSE,SOLID: GRANULOMA CONCENTRIC/TARGET

26. POPCORN CALCIFICATION

27. CALCIFICATION: MALIGNANCY DYSTROPHIC : in areas of necrosis DIFFUSE / AMORPHOUS PSAMMOMATOUS : metastases from mucin secreting tumors such as colon , ovarian cancers CENTRAL CALCIFICATION IN SPICULATED SPN STIPPLED/PUNCTATE : due to engulfment of previous calcified lesion ECCENTRIC DENSE : carcinoids , metastatic osteosarcoma , chondrosarcoma

28. Eccentric dense calcification in right lower lobe carcinoid Amorphous calcification in non small cell ca lung

29. 2. FAT HAMARTOMA LIPIOD PNEUMONIA METASTATIC LIPOSARCOMA

30. AREA OF FAT ATTENUATION IN NODULE : HAMARTOMA

31. 3. CAVITATION LESION WITH WALL THICKNESS < 4 mm -LIKELY BENIGN > 16 mm- LIKELY MALIGNANT 4-16 MM – INDETERMINATE IRREGULAR – LIKELY MALIGNANT THIN SMOOTH – LIKELY BENIGN

32. Benign cavitation Malignant cavitation

33. 4. PSEUDOCAVITATION 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

34. 5. AIR CRESCENT SIGN Aspergilloma Blood clot in a cyst Complicated hydatid disease Ca arising in a cyst Rasmussen aneurysm Mucus plug in cystic bronchiectasis Pulmonary gangrene

35. 7. AIR FLUID LEVEL Usually seen in benign lesions like lung abscess, infected cyst or cavity Intracavitary hemorrhage in cavitary carcinoma

36. 8. 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

37. 9. FEEDING VESSEL SIGN Small pulmonary artery leading directly to a nodule Seen in AVF, hematogenous metastasis, infarct

38. 10. POSITIVE BRONCHUS SIGN A pulmonary lesion that directly abuts, narrows or occludes bronchial lumen is more likely to be malignant Also seen in tuberculoma , pulmonary infarcts, Inflammatory masses This sign helps in whether transbronchial or trans thoracic biopsy helps in histological diagnosis

39. POSITIVE BRONCHUS SIGN

40. CONTRAST ENHANCEMENT NODULE ENHANCEMENT < 15 HU - S/O BENIGN LESION NODULE ENHANCEMENT > 15 HU – S/O MALIGNANT LESION SENSITIVITY - 95 -100% SPECIFICITY -70 -93 %

41. 15 MIN DELAY Malignant nodules: wash-in of >25 HU washout of 5-31 HU Benign nodules: wash-in of < 25 H wash-in of >25 HU in combination with a washout of > 31 HU wash-in of > 25 HU and persistent enhancement without washout

42. The vascular supply of most malignant pulmonary nodules is from the bronchial arterial system. Washout in the malignant nodules takes place via the bronchial veins. In the 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.

43. 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.

44. Net enhancement of > 25 HU Washout of 5-31 HU

45. FALSE NEGATIVE Central necrosis Mucin producing tumors

46. GROWTH RATE ASSESSMENT Volume doubling time is the time required for a lesion to double its volume VDT = t * log2 log Vt /Vo t= time difference Vt = volume at time t Vo= initial volume 1 VDT = 26% increase in the diameter of the nodule

47. Absence of growth over at least 2 yrs period : reliable Indicator of benignity DT less than 1 month – Infection, infarction, lymphoma DT 1 -18 months : bronchial carcinoma DT more than 18 months : Granuloma , Hamartoma , Bronchial carcinoids Doubling time for adeno , undifferentiated , Squamous cell CA is 7.3 , 4.1 , 4.2 months respectively.

48. Slowest growing BACs have VDT of more than 3 years Mets from testicular tumors and sarcomas have VDT of less than a month

49. COMPUTER AIDED DIAGNOSIS Integrated computer system that supports nodule identification, analysis of nodule size, morphology and textural analysis of internal structure of nodule by analysis of high resolution CT data. The CAD system recognizes opacity lesions surrounded by lung parenchymal attenuation as nodules. Therefore, nodules in the subpleural , fissural and costophrenic angle areas might be missed. 

50. Not helpful to pick up lesions less than 4mm Cannot replace the radiologist ; only supporting tool

51. ROLE OF DUAL ENERGY CT IN SPN DECT can decompose enhanced structures into soft tissue and iodine Allows for differentiation of calcification from enhancing tissue by subtraction of iodine component By single scanning after iodine injection, we can measure the degree of enhancement without an additional non enhanced CT

52. ROLE OF CONTRAST ENHANCED DYNAMIC MRI IN SPN Dynamic contrast-enhanced MRI is helpful in differentiating benign from malignant solitary pulmonary nodules Absence of significant enhancement is a strong predictor that a lesion is benign. Presence of rim enhancement – granuloma , network or rim enhancement – hamartoma Presence of homogeneous/ heterogenous enhancement : malignancy

53. Network enhancement : hamartoma

54. Primary lung cancers, time at maximum enhancement ratio was 4 minutes or less For all tuberculomas and hamartomas , time at maximum enhancement ratio was greater than 4 minutes or gradual enhancement occurred without a peak time

55. Maximum relative enhancement ratio of >0.15 is the adopted threshold for a positive differentiation between malignant and benign SPN ( >0.15 = malignant ) 0.80 is the adopted threshold between malignant and infective SPN ( <0.80 = Malignant )

56. Dynamic MRI has been used to assess tumor vascularity ( microvessel counts) and interstitium (degree of elastic and collagen fibers )

57. ROLE OF DW-MRI IN SPN SCALE ( study by Satoh et al ) Nearly no signal intensity Signal intensity between 1 and 3 Signal intensity almost equal to the spinal cord at thorasic spine Higher signal than spinal cord SCORE OF 3 IS THRESHOLD FOR DIFFERENTIATING BENIGN AND MALIGNANT NODULES

58. Disadvantages of MRI Poor resolution Cardiac and respiratory motion artifacts Difficulty in detecting lesion < 1 cm lesion Not useful in peripheral SPN due to signal loss

59. ROLE OF FDG-PET Malignant cells have upregulated metabolisms and proliferate rapidly. This results in marked uptake of FDG False negative results due to - Carcinoids , BAC , Adeno with BAC component , SPN < 10 mm False positive results are due to –Active TB , Histoplasmosis , Rhematoid nodules , Aspergillosis , wegeners granulomatosis Possibility of malignancy with negative FDG-PET is <5%

60. Axial CT Axial PET

61. FOLLOW UP ( fleischner society and American family physicians )

62. ROLE OF SPECT IN SPN The diagnostic ability of 201Thallium SPECT has been reported, with sensitivity, specificity, and accuracy of 85to 100%, 90 to 100%, and 85 to 100%, respectively. Diagnostic accuracy for the pulmonary nodules over 2 cm in size between 201Tl SPECT and FDG-PET is almost the same.

63. THALLIUM SPECT IN SPN

64. INDETERMINATE SPN Transthoracic needle aspiration biopsy for peripheral nodules Fibreoptic bronchoscopy with transbronchial biopsy for endobronchial lesions Video assisted thoracic surgery

65. SOME COMMON BENIGN SPN

66. 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

67. Granuloma

68. 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 featur e

69. AVM X ray – well circumscribed lesion with lobulated outline X ray/CT - Feeding vessels and draining vein can be seen It can be confirmed on CT PULMONARY ANGIOGRAPHY RARELY INDICATED

70. AVM Lobulated,well marginated nodule in the lower lobe Feeding artery (arrow) and an enlarged draining vein (arrowhead ).

71. Nidus of malformation Pulmonary angiogram helps confirm arteriovenous malformation. Note the early draining vein (arrows)

72. 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. INFARCT poorly marginated nodule peripherally in the lower lobe

74. 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

75. BRONCHIAL CARCINOID Typical triad – Well defined ,round lobulated , lesion At the bifurcation Eccentric calcification

76. 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.

77. On a contrast-enhanced CT scan ( mediastinal windowing), the nodule demonstrates marked contrast enhancement and mimics a vascular structure On a contrast-enhanced CT scan ( mediastinal windowing), the nodule demonstrates marked contrast enhancement and mimics a vascular structure

78. ROUND ATELECTASIS FOLDED LUNG Chronic atelectasis that resembles mass X ray and ct – Peripherily located , wedge shaped opacity Based against focally thickened pleura , commonly at lung base Crow feet / comet tail of vesssels 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

79. 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 .

80. BIBLIOGRAPHY LEARNING RADIOLOGY Evaluation of solitary pulmonary nodule :RADIOGRAPHICS TEXTBOOK OF RADIOLOGY AND IMAGING BY DAVID SUTTON DIAGNOSTIC RADIOLOGY BY MANORAMA BERRY Evaluation of solitary pulmonary nodule detected during computed tomography examination : POLISH JOURNAL OF RADIOLOGY Evaluation of the Solitary Pulmonary Nodule : AMERICAN FAMILY PHYSICIANS Solitary pulmonary nodule: A diagnostic algorithm in the light of current imaging technique : AVICENNA JOURNAL OF RADIOLOGY Usefulness of the CAD System for Detecting Pulmonary Nodule in Real Clinical Practice: KOREAN JOURNAL OF RADIOLOGY Dynamic MRI of Solitary Pulmonary Nodules: Comparison of Enhancement Patterns of Malignant and Benign Small Peripheral Lung Lesions: AJR

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