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Reliable, easy-to-read patient information on common medical conditions — written in plain language, free of jargon, and grounded in current evidence. Browse the most frequent diagnoses, understand what they mean for everyday life, and learn which steps and questions help you have a focused conversation with your doctor.

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Solitary pulmonary nodule CT

Introduction

Overview

Overview

Computed tomography is the method of choice for the diagnosis of solitary pulmonary nodule. On CT, characteristic findings of solitary pulmonary nodules, include: ground-glass opacity, rounded mass, and less than 30mm.[1][2] The evaluation of solitary pulmonary nodule will depend on 7 characteristics: calcification patterns, size, location, size, growth, shape, margins, attenuation, and contrast enhancement.[2]

CT

CT

  • Computed tomography is the method of choice for the diagnosis of solitary pulmonary nodule
  • On CT, characteristic findings of solitary pulmonary nodules, include:
  • Single to multiple intraparenchymal lesion
  • Less than 3 cm in size
  • Rounded or spiculated lesion
CT scan showing solitary pulmonary nodules (Picture courtesy: National Library of Medicine)

The evaluation of solitary pulmonary nodule will depend on the following characteristics:

Calcification

  • Calcification patterns are commonly seen in granulomatous disease and hamartomas
  • Calcification patterns are normally a sign of benignancy
  • Characteristic benign calcification patterns of pulmonary nodule, include:
  • Diffuse
  • Central
  • Laminated
  • Popcorn
CT scan showing a calcified solitary pulmonary nodules (white arrow) (Picture courtesy: National Library of Medicine)

Size

  • Different types of size ranges for pulmonary nodule, include:
  • Nodules less than 4mm
  • Nodules between 4mm and 7mm
  • Nodules between 8mm and 20mm
  • Nodules more than 20mm

Location

  • Locations of pulmonary nodule, include:
  • Perilymphatic
CT scan showing a Perilymphatic solitary pulmonary nodules of sarcoidosis (Picture courtesy: Radiopaedia)
  • Perifissural
CT scan showing a Perifissural solitary pulmonary nodule (white circle) (Picture courtesy: Wikipedia)
  • Centrilobular
CT scan showing a Centrilobular solitary pulmonary nodule (black arrowheads) (Picture courtesy: National Library of Medicine)


Growth

  • The growth pattern of the pulmonary nodule plays an important role in the management strategy.[3]
  • Nodule growth should be evaluated on a individual basis and based on the risk assessment score
  • A 4x growth is associated with a 50% risk of malignancy[3]

Shape

  • Different types of shape for pulmonary nodule, include:
  • Polygonal
  • Spherical

Margins

  • Different types of margins for pulmonary nodule, include:
  • Lobulated or scalloped margins
  • Intermediate malignancy probability
  • Smooth margins
    Associated with nodule benignancy
CT scan showing types of solitary pulmonary nodule margins (Picture courtesy: Radiologykey)

Attenuation

  • Different types of attenuation for pulmonary nodule, include:
  • Solid pulmonary nodules
  • Malignancy rate of only 7%
  • Calcified pulmonary nodules
  • Partly solid pulmonary nodules
  • Malignancy rate of 63%
  • Ground glass pulmonary nodules
  • Malignancy rate of 18%

Contrast enhancement

  • Contrast enhancement of pulmonary nodules may be useful to determine benign or malignant features
  • Benign pulmonary nodules usually have a contrast enhancement less than 15 HU

On CT, radiological signs of pulmonary nodule, include:

  • Corona radiata sign: highly associated with malignancy
  • Air bronchogram sign: airway surrounded by collection in alveolar spaces, non-specific sign
  • Halo sign: zone of ground-glass attenuation surrounding a pulmonary nodule or mass on CT images
  • Tree-in-bud sign: CT appearance of multiple areas of centrilobular nodules with a linear branching pattern
  • Cheerio sign: pulmonary nodules with a central lucent cavity as seen on CT. It is due to proliferation of (malignant or non-malignant) cells around an airway
CT Surveillance

CT Surveillance

According to the American College of Chest Physicians (ACCP) for the CT surveillance of pulmonary nodules, recommends the following:[4]

  • If less than 8 mm, use guidelines by the Fleischner society (see table below).
  • For nodules greater than 8 mm in diameter, assess the patients risk of complications from thoracic surgery:
    • If low to moderate risk for complications of surgery, assess probability of cancer by a validated calculation. The model developed at the Mayo Clinic has been the most extensively validated. An open-source version is available online.
    • If high risk for complications of surgery, assess probability of cancer by a validated calculation. If low to moderate risk of cancer follow up with CT scan surveillance. If moderate to high risk of cancer obtain non-surgical biopsy.[5]
Fleischner Society guidelines for follow-up and management of nodules <8 mm
Detected incidentally at non-screening CT[6]
Nodule Size (mm) Low risk patients† High risk patients‡
<= 4 No follow-up needed Follow-up at 12 months.
If no change, no further imaging needed
> 4 – 6 Follow-up at 12 months.
If no change, no further imaging needed 		Initial follow-up CT at 6 -12 months
If no change follow-up CT at 18 – 24 months
> 6 – 8 Initial follow-up CT at 6 -12 months
If no change follow-up CT at 18 – 24 months 		Initial follow-up CT at 3 – 6 months
>If no change follow-up CT at 9 -12 and 24 months
> 8 Follow-up CT at around 3, 9, and 24 months
Dynamic contrast enhanced CT, PET, and/or biopsy 		Same at for low risk patients
† Low risk patients: Minimal or absent history of smoking and of other known risk factors.
‡ High risk patients: History of smoking or of other known risk factors
References

References

  1. ↑ Rosado-de-Christenson ML, Templeton PA, Moran CA (1994). “Bronchogenic carcinoma: radiologic-pathologic correlation”. Radiographics. 14 (2): 429–46, quiz 447–8. doi:10.1148/radiographics.14.2.8190965. PMID 8190965.
  2. ↑ 2.0 2.1 Parker MS, Chasen MH, Paul N (2009). “Radiologic signs in thoracic imaging: case-based review and self-assessment module”. AJR Am J Roentgenol. 192 (3 Suppl): S34–48. doi:10.2214/AJR.07.7081. PMID 19234288.
  3. ↑ 3.0 3.1 Ko JP, Berman EJ, Kaur M, Babb JS, Bomsztyk E, Greenberg AK, Naidich DP, Rusinek H (2012). “Pulmonary Nodules: growth rate assessment in patients by using serial CT and three-dimensional volumetry”. Radiology. 262 (2): 662–71. doi:10.1148/radiol.11100878. PMC 3267080. PMID 22156993.
  4. ↑ Gould MK, Donington J, Lynch WR, Mazzone PJ, Midthun DE, Naidich DP; et al. (2013). “Evaluation of individuals with pulmonary nodules: when is it lung cancer? Diagnosis and management of lung cancer, 3rd ed: American College of Chest Physicians evidence-based clinical practice guidelines”. Chest. 143 (5 Suppl): e93S–120S. doi:10.1378/chest.12-2351. PMC 3749714. PMID 23649456.
  5. ↑ Swensen SJ, Silverstein MD, Ilstrup DM, Schleck CD, Edell ES (1997). “The probability of malignancy in solitary pulmonary nodules. Application to small radiologically indeterminate nodules”. Arch Intern Med. 157 (8): 849–55. PMID 9129544.
  6. ↑ MacMahon H, Austin JH, Gamsu G, Herold CJ, Jett JR, Naidich DP; et al. (2005). “Guidelines for management of small pulmonary nodules detected on CT scans: a statement from the Fleischner Society”. Radiology. 237 (2): 395–400. doi:10.1148/radiol.2372041887. PMID 16244247.

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]Associate Editor(s)-in-Chief: Maria Fernanda Villarreal, M.D. [2] Joanna Ekabua, M.D. [3]