Lung Nodules

Patients with solitary pulmonary nodules are usually asymptomatic; however, solitary pulmonary nodules pose a challenge to both physicians and patients. Whether detected serendipitously or during a routine investigation, a nodule on a chest radiograph raises several questions: Is the nodule benign or malignant? Should it be investigated or observed? Should it be surgically resected?

Most solitary pulmonary nodules are benign, but they may represent an early stage of lung cancer. Lung cancer is the leading cause of cancer death in the United States, accounting for more deaths annually than breast, colon, and prostate cancers combined. Lung cancer survival rates remain dismally low at 14% at 5 years. Early lung cancer, when the primary tumor is less than 3 cm in diameter (stage 1A), may lead to 5-year survival rates of 70-80%. Therefore, prompt diagnosis and management of early lung cancer manifesting as solitary pulmonary nodule may be the only chance for cure.

Taken from eMedicine from WebMD

Bearing in mind that the major distinction that must be made is between neoplastic and inflammatory lesions, solitary pulmonary nodules may have the following causes:

Neoplastic (malignant or benign)
-- Bronchogenic carcinoma
-- Adenocarcinoma (including bronchoalveolar carcinoma)
-- Squamous cell carcinoma
-- Large cell lung carcinoma
-- Small cell lung cancer
-- Metastasis
-- Lymphoma
-- Carcinoid
-- Hamartoma
-- Connective-tissue and neural tumors - Fibroma, neurofibroma, blastoma, sarcoma

Inflammatory (infectious)
-- Granuloma - TB, histoplasmosis, coccidioidomycosis, blastomycosis, cryptococcosis, nocardiosis
-- Round pneumonia
-- Hydatid cyst
-- Inflammatory (noninfectious)
-- Rheumatoid arthritis
-- Wegener granulomatosis
-- Sarcoidosis
-- Lipoid pneumonia

Congenital
-- Arteriovenous malformation
-- Sequestration
-- Pulmonary infarct
-- Round atelectasis
-- Mucoid impaction
-- Progressive massive fibrosis

Concerned about pulmonary nodules?

Follow these ABCs:

A is for Age-few cases before 35, most cases after 45.
B is for Before-compare today's x-rays with those taken before for any change.
C is for Calcium-nodules get their revealing shapes as a result of calcification. And S is for Smoking-if you smoke, quit and get checked.

he diagnostic process focuses on determining whether a pulmonary nodule is cancerous or benign.

The most sure-fire way to make the distinction is by examining the growth rate of the nodule. Benign nodules do not grow much if at all. Cancerous nodules, on the other hand, can double in size on average every four months (some as quickly as 25 days, some as slowly as 15 months). Growth can be evaluated through a series of x-rays or CT (computed tomography) scans over a period of time.

The second most sure-fire way to distinguish a cancerous nodule from a benign nodule is to evaluate its calcification-that is, its development based on its shape and surface. Benign nodules tend to be smoother and more regularly shaped, with more even color throughout. Cancerous nodules are more likely to have irregular shapes, rougher surfaces, and color variations or speckled patterns.

In most cases, x-rays or CT scans provide enough information to make a reliable diagnosis. Doctors might choose to retrieve cells from the nodule for a biopsy. Cells are collected using a needle or performing localized surgery. In addition, an analysis of the patient's sputum can provide diagnostic information.

In almost every case, benign pulmonary nodules require no treatment. Cancerous nodules, however, usually are treated by removing them surgically. Several surgical procedures are used, depending on the size, condition and location of the nodule:

* Video-assisted thorocoscopic surgery is a procedure similar to "scoping" an injured knee. The surgeon inserts the thorascopic device into the lung and withdraws the offending nodule tissue.

* A mini-thoracotomy is a minimally invasive surgical procedure that zeros in on the nodule. It is chosen instead of a full thoracotomy whenever possible.

* A thoracotomy is a comprehensive, invasive procedure whose goal is removal of the diseased portion of the lung-sometime a sizeable "wedge" of the organ.

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The specter of lung cancer hangs over a generation who grew up in homes where ashtrays were as common as shag carpeting. Those youngsters, now entering their 50s and 60s, may have smoked and may have quit, but the risk of cancer remains.

The prospect that CT might find the earliest signs of cancer, or provide peace of mind in its absence, has led some in this generation to seek out the modality. Others struggling with respiratory problems have sought answers through the far more common chest x-ray. For both, lung computer-aided detection offers the potential to find lesions that might otherwise elude human eyes.

When applied to CT data sets, it can help spot lesions as small as 3 mm. Alternatively, CAD software applied in chest radiography can help identify lesions as small as 9 mm.

Dr. Heidi Roberts, an associate professor of radiology in the department of medical imaging for Princess Margaret Hospital in Toronto, describes ImageChecker CT Lung, a software program developed by Hologic/R2, as very useful. False positives have gotten down to a "very bearable minimum," she said. It's so useful, in fact, that she wishes it were on the hospital's PACS rather than a dedicated workstation.

"The only reason we don't use it more often is that we have to get up, go to the workstation, and open the case again," she said. "With the workload we have, that is not always possible."

R2's CAD algorithms examine the CT data in 3D, automatically detecting potential areas of interest, assisting in the detection of solid lung nodules, then measuring them. An algorithm even calculates the percentage of calcification in lesions, a key parameter in determining whether they are cancerous.

But ImageChecker CT, which is in use at Princess Margaret Hospital as part of a lung cancer screening study, cannot provide a definitive diagnosis of cancer. Nor can any other lung CAD for CT.

"It is not a problem with the software. It is a problem of the disease," Roberts said. "Whether the radiologist finds the nodule or the software finds it doesn't matter. It is still difficult to figure out."

Half the population has some nodules, and more than 90% of these are benign, she said. Once small lesions are detected, lung CAD might be used to track the growth of nodules so as to gauge the character of the lesion based on its aggressiveness. Other modalities, such as PET, might be used to gain more information or a CT-guided biopsy might be employed, if the nodule is large enough. When treatment is ordered, CAD can track the size of the nodule to assess its effect.

These detection and measurement capabilities are staples found in lung CAD programs. GE Healthcare's Lung VCAR (volume computer-assisted reading) finds, isolates, and measures lung nodules found in CT data, tracking nodule growth over time. Ditto for Siemens Medical Solutions' syngo Lung CAD, part of the company's LungCARE CT product.

And lung CAD is not constrained to just CT. At the Ogden Clinic in Utah, Dr. Mark Alder uses a CAD program called RapidScreen to check chest x-rays. This software, developed by Deus Technologies, now called RiverRain Medical, came on the U.S. market some five years ago. It has been groomed to detect early-stage lung cancer, identifying solitary pulmonary nodules between 9 mm and 30 mm, as well as other suspicious nodules, on chest x-ray. Alder, the only radiologist on staff at the 50-physician clinic, looks at RapidScreen as a safety net.

"Having this second reader is one way a solo guy like me can always be at his best," he said.

Since RapidScreen was installed at the clinic two years ago, the computerized assistant has confirmed several cases of lung cancer that Alder found on his own. It also spotted one he missed. Everyone getting a chest radiograph, regardless of the reason, goes through a lung CAD screen.

"You want to be sure that in your search for pneumonia or bronchitis, you don't forget to look for lung cancer," he said.

A CPT code in place since 2005 has paved the way for payers to cover lung CAD. Many have responded with reimbursement, albeit typically less than $30 per case. But reimbursement is not an issue at Ogden Clinic, which has a sweetheart deal with the maker of RapidScreen. The clinic pays RiverRain on a per-click basis-and only if it receives reimbursement for the use of the lung CAD. At the same time, having RapidScreen onboard differentiates the clinic from competitors.

"It sets us apart from other radiology groups in the community," Alder said. "With these advantages and the fact that it's impossible for us to lose money on it, lung CAD is really a no-brainer."