Editing Stones: Evaluation and Medical Management (section)

== Imaging for Stone Disease ==

=== Plain Abdominal Film ===
*'''Findings'''
**'''<span style="color:#ff0000">Radiolucent stones (6):</span>'''
*** '''<span style="color:#ff0000">Uric acid</span>'''
*** '''<span style="color:#ff0000">Matrix</span>'''
*** '''<span style="color:#ff0000">Medication stones (4):</span>'''
****'''<span style="color:#ff0000">Xanthine</span>'''
****'''<span style="color:#ff0000">Triamterene</span>'''
****'''<span style="color:#ff0000">2,8-dihydroxyadenine</span>'''
****'''<span style="color:#ff0000">Indinavir</span>'''
** '''<span style="color:#ff0000">Radioopaque stones (4):</span>''' 
***'''<span style="color:#ff0000">Calcium oxalate</span>'''
***'''<span style="color:#ff0000">Calcium phosphate</span>'''
***'''<span style="color:#ff0000">Poorly radioopaque:</span>'''
****'''<span style="color:#ff0000">Magnesium ammonium phosphate (struvite)</span>''' 
****'''<span style="color:#ff0000">Cystine stones</span>'''
***** '''Although magnesium ammonium phosphate and cystine stones are often radioopaque, they are not as dense as calcium oxalate or calcium phosphate stones'''
**'''Nephrocalcinosis'''
***'''Formation of diffuse deposits of calcium throughout the kidneys'''
****'''Usually occurs within the renal medulla''' but occasionally it has been found in the cortex or within both the medulla and the cortex
****Minute calcifications seen in early stages may not be visible
***'''Can give rise to renal colic and hydronephrosis from dislodged calcific foci'''
***[[File:Nephrocalcinosis.jpg|alt=Nephrocalcinosis. Source: Wikipedia|thumb|Plain film x-ray demonstrating bilateral diffuse calcium deposits in the kidneys. Source: [[commons:File:Nephrocalcinosis.jpg|Wikipedia]]|400x400px]]'''Causes[https://radiopaedia.org/articles/medullary-nephrocalcinosis §]'''
****'''Medulla'''
*****'''Type 1 (distal) RTA'''
*****'''Hyperparathyroidism'''
*****'''Medullary sponge kidney'''
*****'''Hypervitaminosis D'''
*****'''Milk-alkali syndrome'''
*****'''Sarcoidosis'''
*****'''Hyper/hypothyroidism'''
*****'''Other pathological hypercalcemic or hypercalciuric states'''
******'''Cushing syndrome'''
******'''Multiple myeloma'''
******'''Bartter syndrome'''
******'''Bone metastases'''
****'''Pyramids'''
*****'''Hyperuricemia'''
***** '''Infection (particularly renal tuberculosis)'''
*****'''Sickle cell disease (leading to infarction and subsequent dystrophic calcification)'''
*****'''Renal papillary necrosis'''
*****'''Drugs'''
*****'''Furosemide abuse'''
****'''Corticol COAG'''
*****'''Corticol necrosis'''
*****'''Oxalosis (Primary hyperoxaluria)'''
*****'''Alport syndrome'''
*****'''Glomerulonephritis (chronic)'''
*Test characteristics[https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5443345/ §]
**Sensitivity: 57%
**Specificity: 76%
*Advantage(s)
**Availability
**Relatively low radiation exposure
***0.7 mSv with KUB[https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5443345/ §]
**Cost (least expensive)
*'''Disadvantages'''
**'''Inability to visualize small stones'''
**'''Inability to visualize stones due to overlying/underlying anatomy (bones, phleboliths, etc.)'''
**'''Underestimates >90% of stones >10mm'''

=== Ultrasound ===
* Test characteristics[https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5443345/ §]
**Sensitivity: 84%
**Specificity: 53%
*'''Advantages'''
**Availability
**No radiation exposure
**Cost (5x cost of KUB)[https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5443345/ §]
*'''Disadvantages (2):'''
** '''Inability to visualize most ureteral stones'''
** '''Poor correlation between measured and actual stone size and location'''
*** '''If stone''' 
****'''<10mm, US underestimates size of stone 1/3 of the time'''
**** '''>10mm, US overestimates size of stone 1/3 of the time'''
***US and CT measurements correlate 2/3 of the time

=== CT scan (without contrast) ===
* '''Findings'''
**'''Pure uric acid stones have much lower Hounsfield units than calcium types'''
**'''Forniceal extravasation'''
*** Usually associated with a small distal ureteral calculus.
*** '''Should be similarly to other ureteral stones:''' intervention should be undertaken when there is an associated fever, nausea/vomiting, or unrelenting pain. Otherwise, conservative observation is appropriate.
*Test characteristics[https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5443345/ §]
**Sensitivity: 95%
**Specificity: 98%
*'''Advantages'''
**'''Most sensitive modality for stones'''
*Disadvantages
**Exposure to radiation[https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5443345/ §]
***Low-dose CT is ≈3.0 mSv, standard CT without contrast is 10.0 mSV
**Availability
**Cost (10x cost of KUB)[https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5443345/ §]

=== MRI ===

* Test characteristics[https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5443345/ §]
**Sensitivity: 82%
**Specificity: 98%
*Findings
** Stones appear as filling defects
* Advantages
** No exposure to radiation
* Disadvantages
** Availability
** Cost (most expensive, 30x cost of KUB)[https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5443345/ §]