Hi, welcome back. I'm Leslie Quint from the Department of Radiology at the University of Michigan. And today, we'll be talking about imaging of small cell lung cancer. My objectives for this talk are to review the recommended imaging techniques for patients with newly diagnosed small cell lung cancer. And to illustrate the typical imaging findings. Let's start out with a pre-lecture question. Which imaging study is best in the assessment for brain metastases in patients with small cell lung cancer? And you can choose from an FDG-PET scan, a Head CT with IV contrast, a Head CT without IV contrast, or a Head MRI. Please choose your best option and we'll get back to this at the end of the talk. Well, let's get started. Imaging is the principal method that we have for staging patients with small cell lung cancer. There are various different imaging modalities that we use in these patients. The first one is a chest CT scan with IV contrast material. The scan starts at the lung episis and extends down to include the adrenal glands. Secondly, we always get brain imaging on these patients, and MR is preferable to CT in this setting. And thirdly, we'd like to get an FDG-PET scan if we have access to that technique in our own institution. If we don't have access to a PET scan, then we'd like to scan the abdomen using CT with IV contrast. And we also get a technetium 99m bone scan to look for bone metastases. Small cell lung cancers are staged using the same TNM system that we use for non-small cell lung cancers. But, in addition, we also generally assign the patient to a clinical stage which is either limited stage or extensive stage. And when we say limited, we mean that the tumor can be encompassed into a reasonable radiation therapy port. Let's talk a little bit about the primary tumor. The vast majority of small cell lung cancers are centrally located in the hilum or the mediastinum, arising from the main stem bronchi. Quite often on our scans, we see a hilar or a mediastinal mass without a visible lung nodule. Generally, these tumors are very large and bulky, and they may surround and narrow a central bronchus. Quite often, there is post-obstructive atelectasis or pneumonia peripheral to the central mass. Here's an example of a central mass here in the hilum, it's extending into the mediastinum. The mass is encasing the left upper lobe bronchus and narrowing the bronchus. And we see there is post obstructive left upper lobe atelectasis. So this is a very typical appearance for a small cell lung cancer. In this patient, we also see some prominent right hilar lymph nodes as well as subcrional lymph nodes. So this is the image that we just saw a moment ago. This is the pre-treatment scan. This patient then underwent chemo-radiation therapy and came back six weeks later. And here's the post treatment scan. Notice that the tumor melted away and it's very difficult for us to see a very good initial response to therapy. Although unfortunately, these lesions do come roaring back later on. The primary tumor is frequently encase and invade adjacent structures. Such as the trachea, the esophagus, the heart, the superior vena cava and other vascular structures. And they frequently also will grow directly into the chest wall. Here's an example of a patient who had a small cell lung cancer on the right lower lobe. The CT-PET scan shows that the tumor is extremely FDG avid. It is growing directly into the posterior chest wall, as well as into a neural foramen. This simply represents some contralateral atelectasis that was not related to the neoplasm. Although, the vast majority of the time, these tumors present as large, bulky, central masses. Rarely less than 5% of time, we can see them as a small peripheral lung nodule without any central lymph node enlargement. Here such an example, this patient actually has two tiny adjacent lung nodules on CT, we didn't see anything else on the scan. A PET scan was obtain and these two nodules are seen together as one very hot focus. But we didn't see any evidence of other spread, either in the hilum, the mediastinum, or elsewhere. So this a rare occurrence, we occasionally see this. And these patients may actually benefit from surgical resection. Whereas the patients with the large bulky central masses do not typically go to surgery. What are the common sites of spread of disease in patients with small cell lung cancer? These cancers typically will spread to the pleura space, to the pericardium, as well as to the contralateral lung. In this patient, we see a right lower lobe lung cancer. This was a small cell lung cancer, it's touching the right hilum. There's a mildly enlarged separate right hilar lymph node. We also see a small pericardial effusion, as well as bilateral plural effusions, and these effusions represented spread of disease. These were neoplastic effusions. What about extensive stage of disease? Where should we look for sites of spread? We need to carefully scrutinize the bones, as well as the liver. The adrenal glands and the brain. And these are the percentage of cases where we do see spread to these different regions. Here's an example of a patient with a large bulky central left upper lobe mass, showing broad contact with the aorta. The mass is invading the mediastinum. We also see that there's a mildly enlarged lymph node in the left superior mediastinum. A PET scan was obtained, and we noticed that the primary mass is very FDG avid. That's very typical. And we also see that lymph node in the left side of the superior mediastinum. The PET scan also shows us this small focus over here, which we did not see on our CT scans. Where is that focus? Well, let's look at the axial CT, PET image. This one here is the lymph node that we saw on our diagnostic CT scan. This, however, that we saw in the PET scan is over here, and that localizes to the second rib. So this was a rib metastases that was not visible on our conventional scan. FDG-PET scanning is about 95% accurate in detecting extensive disease. And that clearly affects the choice of therapy. PET may change management in up to about a quarter of patients and that happens mostly by upstaging the disease. So, PET will show us lesions in various places such as the rib that we just saw in the previous case. PET will show us lesions that are not detected by conventional imaging. Very frequent occurrence. And PET commonly modifies determination of the radiation therapy port. So here's an example. This was from our diagnostic chest CT. We start at the apices. We scanned down to the level of the adrenal glands. And we get some liver in the scan. And if we look at the liver here, it's a little heterogeneous. A little bit hard to tell if there's really something going on there. It's a lot more obvious on the combined CT/PET image. On our right, there are multiple FGG avid lesions throughout the liver. If we look back, we can find them, but they're a lot easier to find on the pet scan. Well what about brain imaging? Do we do brain imaging? How often do we do it? Let's look at some of the numbers. Brain metastases are present in 10 to15% of neurologically asymptomatic patients. Including 12% of patients otherwise thought to have limited stage disease. So it's extremely important that we do brain imaging on all of our patients with newly diagnosed small cell lung cancer. Head MR and head CT are more sensitive than PET scanning in this setting. That is because normal brain tissue will have quite a bit of FTG uptake and that can obscure a brain metastases. And when we're trying to make the choice between MR and CT. MR is more sensitive and more specific compared to CT scanning. Here's an example of a patient with a right hilar mass. This was a small cell lung cancer, very typical appearance. We also see that there are bilateral plural effusions and those are suspicious for spread to the plural spaces. A head scan was obtained. This was a CT scan and notice that there are multiple lesions here in the brain, and these were brain metastases. So this is a very typical finding. That leads us to our post-lecture question. So if you remember, we ask before the lecture which imaging study is best in the assessment for brain metastases in patients with small cell lung cancer? And I asked you to choose from an FDG-PET scan, a head CT with IV contrast, a head CT without IV contrast, or a head MRI. So please now go ahead and pick your best choice. And the best choice here is clearly head MRI. That brings us to our take home points. Routine imaging for our patients with newly diagnosed small cell lung cancer is done with a combination of IV contrast enhanced chest CT, imaging of the brain preferably with MR but sometimes with CT. And also, whole body FDG-PET scanning. Detection of extensive stage disease will change therapy. And the places where we should look for distant metastases include bone, liver, adrenals and brain. So that's where we should concentrate our attention with our multiple imaging studies. And with that, I thank you very much for your attention.
