Diagnostic Imaging Required Reading: Pg 125-138 Des Jardins, Clinical Manifestations and Assessment of Respiratory Disease, 4th edition.

Types of Diagnostic Imaging Studies Chest film (CXR) Computerized Axial Tomography (CT scan) MRI Angiography Nuclear Medicine scans PET scan

CT Scan An x-ray procedure which combines many x-ray images with the aid of a computer to generate transverse cross-sectional views and at many different angles around the body. These images are processed by a computer to produce cross-sectional pictures of the body. In each of these pictures the body is seen as an x-ray "slice" of the body, which is recorded on a film. This recorded image is called a tomogram. "Computerized Axial Tomography" refers to the recorded tomogram "sections" at different levels of the body. http://www.medicinenet.com/cat_scan/article.htm

CT Scan Indications: When additional diagnostic information is required to investigate and guide treatment. CT are ordered for tumors or masses, fluid, injury (trauma), or other disease process.

CT Scans CT may also used to detect both acute and chronic changes in the lung parenchyma and for detection of airspace disease: Pneumonia Pulmonary fibrosis Emphysema Lymphadenopathy Pulmonary embolus Aortic dissection

CT Scan Contrast media such as Iopamiro, Isovue, Niopam, Solutrast can be given intravenously to help enhance the image and help clarify soft tissue structures.

MRI Similar indications to that of CT scans. Advantages Higher resolution images No ionizing radiation More planes of dissection Transverse (CT) Coronal Sagittal

MRI Disadvantages Expensive Image acquisition takes much longer Safety issues (powerful magnet field can cause objects to fly toward the magnet) 6 ft gantry makes patient care difficult

MRI Safety Check with Rad. Tech before entering room: Ferric metal items (attracted to magnets) prohibited Some electronic items may become non-functional Plan appropriately for safe patient monitoring Absolutely do not bring oxygen cylinders near the room. Plan ahead

MRI

Fluoroscopy

Fluoroscopy Fluoroscopy is the projection of real-time two dimensional x-ray images. Modern equipment generally projects the image on a television monitor. “Fluoro”, as it is known is useful for the placement of certain lines. Injection of contrast dye under fluoro is a procedure known as angiography.

Angiography The injection of contrast dye into vessels.

Angiography Fluoroscopic images can be captured and recorded so one can watch contract dye fill the vascular system of any organ. This is often done in “Special Procedures” Heart: Heart Cath Lab.

Angiography Advantages Disadvantages Very specific diagnosis and treatment. Blocked vessels can be opened and “stented”. Disadvantages Angiography is potentially dangerous: Dye replace blood for a few seconds, and therefore can potentially infarct the tissues

Common types of Angiograms Heart catheterization Coronary angiography Right heart ventriculography Left heart ventriculography Cerebral angiography (Extremity angiography (arm or leg) Renal angiography (kidneys) Pulmonary angiography (lungs) Lymphangiography (lymph vessels) Aortography Retinal angiography

Pulmonary Angiogram Indication: Pulmonary Embolism 98% sensitive

Pulmonary Angiography Advantage: Gold standard for diagnosis of pulmonary embolism Disadvantage: Higher mortality rate. Possibly an unacceptable risk in unstable patients.

Nuclear Medicine A radioactive element is injected into the patient and tracked with a “gamma camera” with the elements appearing as tiny dots on the screen/film. Nuclear medicine is distinctly different than contrast since the element used in nuclear medicine does on show up on x-ray like contrast will.

Nuclear Medicine: V/Q Scan of Lungs

Nuclear Medicine Advantages Disadvantages No electromagnetic radiation used (no need for practitioners to protect themselves) Easily tolerated, even in the sickest patients. Disadvantages Poor resolution and often not very specific.

V/Q Scan A V/Q (ventilation/perfusion) scan is a test that requires dual induction of radioactive elements at separate intervals: A radioactive element is injected into the blood stream that has an affinity for pulmonary capillaries A radioactive element is inhaled, filling the communicating airspaces.

V/Q Scan By superimposing the ventilation study on the perfusion study, probability of pulmonary embolism can be suggested. A Radiologist reads the study and looks for one or more areas of ventilation with no perfusion.

V/Q Scan Two medium to large perfusion defects on V/Q mismatch Probability of PE: 90% One medium to large perfusion defect on V/Q mismatch Probability of PE: 50% Small perfusion defects Probability of PE: Low Source: Family Practice Notebook http://www.fpnotebook.com/LUN160.htm

PET Scan Positron Emission Tomography Equipment similar to CT scan equipment Useful in detection of cancer Useful in diagnosing effectiveness of cancer treatment.