Chest Search Patterns

 

Noncontrast Chest CT Nodule followup:

 

Image Setup:

Current study:  thin sections, 3-5 mm slice thickness axial on soft tissue window, 3 mm coronal and sagittal reformats.

Most recent prior:  thin section axials

Additional prior:  IMO, choose prior approx 2 yr prior to current study so could potentially exclude malignancy of solid nodules seen on the current study if stable for >2 yrs.

Consider opening extreme remote prior for further evaluation of chronic nodules or other findings

-----------------------

How to find nodules:

Scan up and down on axials, focus on anterior, middle, or posterior thirds of lungs. 

WHERE DO YOU MISS NODULES??? 

edit- Just saw a near miss 7/7/2015.  This was in a the parahilar area, more specific in right where the RLL basilar segmental bronchi bifurcate.  Have to look at these areas first, the bronchus bifurcation / split regoins, ie RLL basilar segments, RML bronchi takeoff, RUL segmental takeoffs and so on for the left lobe.  Can EASILY miss a mass (3 cm) right here. 

 

Usually in the para hilar regions where hilar structures (vessels, bronchi) can obscure or prevent you from "seeing" nodules and even masses.  During one readout, attending missed a large (3 cm) mass in the parahilar regions which was clearly seen on recent Pet CT, so this happens.

------------------------

What types of nodules to look for:

solid

ground glass

solid and ground glass

 

-calcified nodule could be granuloma which is benign, often central, laminar or diffuse

-fat containing nodule likely to be hamartoma which is benign

-popcorn calcification likely hamartoma, benign

--------------------------------

How long to follow nodules?

-solid nodules:  2 yrs and then considered benign

-GGO nodules:  according to some sources, forever, probably at least 6 yrs, no clear guideline

mixed nodules (solid and GGO):  probably similiar followup to GGO nodules, remember to also measure solid component

------------------------------

Size guidelines:

< 3 mm, approx 0.2% chance of being malignant

>3 mm < 8 mm, approx  2.7% chance of being malignant

=/>8 mm, approx 20% chance of being malignant

 

Moral of story: don't miss nodules > 8 mm

Additionally, can characterize 8 mm nodules with PET CT and / or biopsy which should be recommended.

Alternative strategy:  short term interval followup of 3 months to exclude infectious etiology

-------------------------------

Common themes in nodules followup imaging:

 

Emphysema:  usually centrilobular, usually worse in the apices

 

Multiple centrilobular nodules which are tiny:  consider lumping multiple small nodules into an infectious category such as acute PNA or chronic appearance of old TB

 

Peripheral reticulation and ground glass (shmutzy looking peripheral lungs for lack of better term):  consider diagnosis of respiratory broncholitis-----------------------------------

Re. Lung Ca:

 

remember adenocarcinoma most likely solid nodule but can also look like consolidation (AdenoCa-in-Situ)

Squamous cell:  Sentral and cavitates, can be inside bronchi

Small Cell will look horrible at presentation which probable mets, will be hard to tell whats in the lung and whats in the mediastinum

Carcinoid in a younger patient, inside an airway and enhancing on post contrast

 

 

Indications for Noncontrast Chest CT (clinical histories):

1.  Lung Nodule followup / Lung Ca Screening CT

2.  Possible Pneumonia

3.  Possible Interstitial Lung Disease

4.  Followup of ascending thoracic aortic aneurysm

 

Remember to mention bronchial wall thickening

 

 

 

Interstitial Lung Disease Dictation Help:

 

UIP vs. NSIP

the distinction is always difficult

-in fact, studies have been done where experts in radiology, pulmonology, and pathology tried to reach consensus in diagnosing these entities and something like disagreement between these two diagnoses 40% of the time

 

 

some helpful things re. UIP

-Stacked cysts, bronchietctasis - two things that usually mean UIP

-honeycombing- UIP usu

 

Some helpful things re. NSIP:

-subpleural sparing- almost definitvely NSIP.  Don't always see this though

 

---------------------------

Pleural Shtuff

 

Every now and then will find pleural abnormalities (aside from effusions or other fluid).  What to do about them?

 

• pleural plaques:  say something about asbestos related pleural disease, possibly also silica exposure

• angry looking large pleural based tumor:  probably mesothelioma

• pleural thickening:  can be benign or maligannt.  often due to asbestos or silica exposure, also think about post inflammatory (after an empyema), after a hemothorax, also throw in METS and LYMPHOMA

• consider:  round large ball like tumor: solitary fibrous tumor of pleura:  kinda like a meningioma of the pleura, similiar demographics too