Term
What is meant by each of the following measures of diagnostic value of tests?
1) Sensitivity
2) Specificity
3) PPV
4) NPV |
|
Definition
1) True positive/ (true positive + false negative)
2) True negative/ (false positive + true negative)
3) True positive (true positive + false positive)
4) True negative/ (true negative + false negative) |
|
|
Term
| What diagnostic tests have the highest "relative resolution" |
|
Definition
Sensitivity, Specificity, Resolution metric
1) MRI, CT and Endoscopy have highest
**MRI and endoscopy cost a ton though!
2) X-rays are medium
3) Ultrasound and gastric emptying (radiolabel) have low |
|
|
Term
Why are the stomach, small bowel and colon not well visualized on ultrasound?
What are the advantages/disadvantages to this technique? |
|
Definition
Air containing structures block sound wave
GREAT for gall-stones, but not small bowel obstruction
1) Advantages include the fact that US is safe, painless, non-invasive, available and inexpensive.
2) Disadvantages include operator-dependence, obesity issues, lower resolution than CT for soft tissue lesions and air-blocking. |
|
|
Term
| Why might you decide to order a CT of the abdomen? What might preclude this decision? |
|
Definition
1) Avoids "air" issues of ultrasound and has high organ resolution
**Great for liver, gallbladder, pancreas and small bowel, especially to see masses**
2) Moderate cost and high exposure to radiation are issues, as well as patient must stay still and IV dye allergies. |
|
|
Term
| Why might you decide to order an MRI of the abdomen? What might preclude this decision? |
|
Definition
1) Hemochromatosis (iron deposition in liver) and Hemangiomas (vascular anomalies in liver)
- MRCP is great for bile ducts and pancreatic duct
2) Expensive |
|
|
Term
| How can upper endoscopy be used to evaluate GERD? |
|
Definition
Symptoms should be severe and unresponsive to PPi, or complications like bleeding or Barrett's should be expected.
Endoscopy will reveal esophagitis, ulceration and early stricture of distal esophagus.
If Barrett's is noted, take a biopsy and look for dysplastic changes! |
|
|
