Help me interpret PET results

[razp]

Hi - my dad has vasculitis (has had it for 15+yrs well managed on immunosuppressants). He has been followed for a very slow growing lunch nodule (1mm in 2011, 4mm in 2017 and 7mm in 2024). His team recommended a PET scan. results below. Question: he seems to have a ton of nodules (could be his vasculitis?) - do any of them seem high risk? he had a recent chest infection about 2 weeks before the PET scan. Could that have impacted the test?

 

CLINICAL INDICATION:

67-year-old male with slowly growing pulmonary nodule. GPA (Eosinophilic granulomatosis with polyangiitis) with slowly growing pulmonary nodule. ?malignant ?inflammatory

FINDINGS:

Chest:

Right lung: Lateral basal right lower lobe 7 mm pulmonary nodule displays lowgrade avidity (less than that of the mediastinal blood pool). Solid appearing right apical upper lobe 6 mm pulmonary nodule shows structural progression since April, and demonstrates mild avidity, SUV max 3.1.

Posterobasal right lower lobe ground-glass and tree-in-bud nodularity remains structurally stable with lowgrade avidity, with new area of ground-glass opacity in nodularity at the same level lateral to this.

Left lung: New left upper lobe subpleural ground-glass nodule adjacent to the aortic arch measuring 4 mm displays lowgrade avidity, SUV max 2.8. Clustered nodules in the left upper lobe anterior segment have also developed since the previous study, displaying lowgrade avidity and favoured inflammatory. New, 3 mm left lower lobe superior segment pulmonary nodule is below PET resolution. Left upper lobe peribronchovascular pulmonary nodule measuring 6 mm on recent CT is not clearly identified. Mildly avid subpleural nodularity within the inferior lingula, structurally similar to prior CT

 

Moderately avid bilateral pulmonary hilar, aorta pulmonary and subcarinal nodes are favoured reactive/granulomatous in aetiology however, if any of the pulmonary lesions prove neoplastic nodal disease is not excluded. Extensive brown fat activation within the chest limits assessment of the mediastinal structures.

Retained secretions within the mid to upper trachea.

CONCLUSION:

Multiple pulmonary nodules. Increased size of the right apical pulmonary nodule compared with imaging from 3 months earlier may be inflammatory or infective in aetiology, however, neoplasia is not excluded and close surveillance is recommended. The lateral basal right lower lobe pulmonary nodule is non avid. however, given the interval growth an indolent pulmonary neoplasm is not excluded. Multiple further pulmonary nodules and areas of mixed ground-glass and nodular infiltrate are favoured infective or inflammatory and will benefit from continued surveillance.

Multiple mildly avid intrathoracic nodes are likely reactive or granulomatous, however, if any of the nodules prove neoplastic disease here is not excluded.

[LouT]

Razp,

Welcome to our forums.  Let's start with a few data points...

1. most lung nodules are not malignant.

2. PET Scans are useful as part of a diagnostic process that includes other forms of imaging including; CT Scan, X-Ray, etc.  It's based on the premise that malignant tissue will have increased uptake of the solution containing radioactive glucose.  But they are not definitive tests for malignancy.  They are indicators that when solidly positive would lead to a tissue biopsy, which is the gold standard for confirming malignancy.  You can learn more about "Imaging Tests" here. 

3. The more tissue (in this case a nodule) has an uptake of the glucose (measured as Standardized Uptake Value or SUV) the more possible it is that the tissue is malignant.  The nodule that does absorb the glucose would be called "avid"  or "FDG avid".  In this case they have concluded that the nodule is "non-avid" meaning that it is not absorbing the glucose solution notably.  They do recommend monitoring because of the growth of the nodule though.

In my diagnosis process for LC (Lung Cancer) my SUV numbers were inconclusive and a tissue biopsy wasn't possible at the time so it was recommended to monitor the nodule.  That is what is being recommended for you here.  So, keep the follow up appointments and scans and if they become more convinced that this nodule is malignant they will likely do a tissue biopsy.

I hope this helps you out.  Sometimes all the different tests and measurements can be confusing.

Lou

[Tom Galli]

Razp,

Welcome here.

The SUV level of concern for metastatic lung cancer is 2.0. Anything higher is concerning but values between 2 and 4 may be explained by other causes (inflammation, infection, or recent lung illness).  Your dad has two nodules that warrant watching. Yes, a recent chest infection would likely impact the results of the test.

Your dad's nodules are still very small and perhaps too small to target with a needle biopsy. Only a tissue biopsy can disclose metastatic lung cancer. At this juncture, your dad's doctor may counsel frequent CT scans to keep an eye on the enlarging nodules and that would be a good idea. This is a personal story of PET scan results for more insight into SUVs and what they mean.

Stay the course.

Tom