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Precious Stones: Gems of the urogenital system
Nordic Forum 2017, Helsinki, Finland
Ken F Linnau MD, MS
Emergency Radiology
kingstonegems.com
59 year old woman
• Intermittent right flank pain
• Pain radiates into the right groin
• Hematuria
• No abdominal tenderness on exam
What does she have?
– Diagnosis and differential
What needs to be done?
– Medical treatment or surgical intervention
Outline - Nephrolithiasis
• Rationale approach to imaging diagnosis
• CT KUB vs US
• Differential considerations
• Imaging technique
• Low dose scan
• Positioning
• Unusual urolithiasis
• Indinavir stone
• Staghorn calculi
• XGP
• Bladder stones
• Dual Energy CT and nephrolithiasis
59 year old woman
• Intermittent right flank pain
• Pain radiates into the right groin
• Hematuria
• No abdominal tenderness on exam
What does she have?
– Diagnosis and differential
59 yof rt flank pain and hematuria
CT findings of nephrolithiasis
• Dens calculus in the course of the urinary collection
system
Indirect secondary signs:
• Dilatation of the upstream collecting system • Increases with duration of pain
• Perinephric fat stranding
• Includes the peripelvic renal fat
35 yof RLQ and rt flank pain
US findings of nephrolithiasis
• Echogenic calculus in the course of the urinary
collection system
• Posterior acoustic shadowing
Indirect secondary signs:
• Dilatation of the upstream collecting system • Increases with duration of pain
CT or US for suspected nephrolithiasis?
• Non-contrast helical CT and Ultrasonography
• Both are appropriate initial imaging modalities.
• Missed diagnoses resulting in complications are
equivalent.
• Serious adverse events are similar.
• Return visits to ED are similar.
• Length of stay in ED is longer when US is done by
radiologist.
Smith-Bindman R, et al. NEJM (2014): 371;12: 1100
CT vs US
CT US
Sensitivity 88 54 vs 57
High specificity and positive exam confirms diagnosis
41% needed CT after US
Radiation
70% more dose at 6 months
Alternate diagnosis in 33%
Smith-Bindman R, et al. NEJM (2014): 371;12: 1100
42 yof with right sided abdominal pain for several days.
Now localizing to RLQ, N/V, WBC 13 tsd, UA: ++ RBC
DDx for nephrolithiasis
• Appendicitis, intestinal obstruction, diverticulitis:
• No hematuria, usually abdominal tenderness
• Ovarian torsion, ruptured cyst, dysmenorrhea
• Billiary colic or cholecystitis
• No hematuria
• Less common:
• Aortic aneurysm
• Intestinal ischemia
• Ectopic pregnancy
• Herpes zoster
Hematuria useful disciminator
No hematuria in 10-30% of nephrolithiasis,
especially when onset of pain more distant
43 yom colicy LLQ pain, r/o diverticulitis
Treatment of urolithiasis
• Pain control: NSAIDs
• If urosepsis: emergent decompression
• Ureteral stent or nephrostomy
• Stone < 10 mm: usually passes
• Treat symptoms
• Stone > 10 mm: urologic evaluation
• Extracorporeal Shock Wave Lithotripsy (ESWL)
• Nephrolithotomy
43 yom colicy LLQ pain, r/o diverticulitis
Pelvic phlebolith
31 yom rt flank pain
31 yom rt flank pain
CT technique
• Low dose technique
• Similar sensitivity and specificity for larger stones
• Less reliable for stones < 2 mm
• Less reliable in obese patients BMI > 30
• Consider prone scanning position
• Allows detection of passed stones (dependent location)
53 yom rt flank pain, HIV+, on HAART
59 yof lt flank pain
59 yof lt flank pain
https://www.pinterest.com/monfakwei/antlers
59 yof lt flank pain
CT KUB from 3 months earlier
Staghorn calculi
• Struvite (Mg ammonium phosphate)
or Ca++ carbonate apatite stones
• Branched stones that fill part or entire renal pelvis
• “Infection stones”
• Strong association with UTIs
• Urea splitting organisms (Proteus, Klebsiella)
• Can grow rapidly
• Deterioration of kidney function
• End-stage renal disease
• Urosepsis
• Surgical treatment often necessary
• Shock wave lithotripsy
• Percutaneous nephrolithotomy
https://www.pinterest.com/monfakwei/antlers
87 yom s/p fall
PV
10 min delayed
Xanthogranulomatous pyelonephritis (XGP, XPN)
• Renal tissue is replaced: chronic inflammation
• Dilated calices surrounded by
• Xanthomatous tissue (“yellow”)
• Necrosis, inflammatory cells: lipid-laden macrophages
• Giant cells and cholesterol clefts
• Unilateral
• Renal stones, often staghorn stones
• Infrequent association with renal cancer
• Peri-renal extension and fistulation
• Nephrectomy
60 yom CP, fall during wheelchair transfer
66 yom SCI patient annual surveillance
Bladder stones
• Urinary calculus in bladder
• Bladder outlet obstruction (e.g. BPH)
• Foreign body (e.g. urethral catheter)
• Infections with urea-splitting bacteria
• Neurogenic bladder
20 yof rt flank pain and hematuria
20 yof rt flank pain and hematuria
Dual Energy CT image
Dual Energy (DE) CT
• Two x-ray sources and 2 data acquisition systems mounted on same x-ray gantry
• Each x-ray source has independent high voltage generator
• Allows for independent control of both potential and current
– E.g.80/ 100 kV & 140 kV
• Simultaneous low & high energy images can be reconstructed
Remy-Jardin et al. Radiol Clin North Am. 2010 Jan;48(1):193-205. Courtesy S Nicolaou, UBC, Canada
• Xrays: electromagnetic radiation of different wavelenghths: spectrum
• X-ray spectrum differs by kV
• Tin pre-filtration for 140 kV
• Spectral separation allows characterization of materials
DE CT exploits X-ray spectrum
S1: 80 kV x 104
15
10
5
0 50 100 150
80 kV
140 kV
photon energy (keV)
0.4 mm Sn
+ SPS
140 kV + SPS
S2: 140 kV
Courtesy S Nicolaou, UBC, Canada and Siemens
Principle of Dual Energy CT
Courtesy S Nicolaou, UBC, Canada
Principle of DE CT
Courtesy S Nicolaou, UBC, Canada and Siemens
Johnson T et al. Eur Radiol. 2007; 17:1510-7.
Material Characterization Materials can be differentiated by applying two X-ray spectra and analyzing attenuation differences. Technique works well for compounds with high atomic numbers taking advantage of the photoelectric effect ~Z3
Courtesy S Nicolaou, UBC, Canada
• Bone • Iodine • Uroliths
Image Based Methods Modified 2-material decomposition: Characterization of kidney stones
• Calcified stones are BLUE (heavy ions)
Uric acid stones are RED (Nitrogen, Oxygen containing)
HU at 140 kV
HU at 80 kV
high Z
low Z
Courtesy S Nicolaou, UBC, Canada
20 yof rt flank pain and hematuria
Calcified stone, mixed composition
59 yof rt flank pain and hematuria
59 yof rt flank pain and hematuria
Uric acid stone
DE CT stone characterization
• Uric acid stones respond well to medical therapy • DE ratio around 1.0
• Cysteine stones are resistant to ESWL
• Calcium stones are most common, different
types
• Calcium oxalate monohydrate least susceptible to
ESWL
• DE ratio < 1.4
• Other calcium containing stones more fragile: ESWL
DE CT can be helpful to in treatment decision
making
Summary
• Hematuria?
• Non-contrast CT and sonography are equivalent first
tests
• Use low dose technique and prone positon for CT
• Stone size and location is important for treatment
• DE CT for stone composition
Thank you. [email protected]
kingstonegems.com
References
• Ultrasonography versus computed
tomography for suspected nephrolithiasis.
Smith-Bindman R, Aubin C, Bailitz J, Bengiamin RN, Camargo CA Jr,
Corbo J, Dean AJ, Goldstein RB, Griffey RT, Jay GD, Kang TL, Kriesel
DR, Ma OJ, Mallin M, Manson W, Melnikow J, Miglioretti DL, Miller SK,
Mills LD, Miner JR, Moghadassi M, Noble VE, Press GM, Stoller ML,
Valencia VE, Wang J, Wang RC, Cummings SR. N Engl J Med. 2014 Sep
18;371(12):1100-10. doi: 10.1056/NEJMoa1404446. PMID: 25229916
• In vivo characterization of urinary calculi on dual-energy CT: going a step
ahead with sub-differentiation of calcium stones. Acharya S1, Goyal
A1, Bhalla AS1, Sharma R2, Seth A3, Gupta AK1. Acta
Radiol. 2015 Jul;56(7):881-9. doi: 10.1177/0284185114538251. Epub
2014 Jun 17. PMID: 24938664