Hounsfield Units on Computerized Tomography Predict Stone-Free Rates After Extracorporeal Shock Wave Lithotripsy

Pareek, Gyan; Armenakas, Noel A.; Fracchia, John A.

doi:10.1097/01.ju.0000055608.92069.3a

Cited by 171 publications

(116 citation statements)

References 12 publications

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“…This result differs from several published studies [9][10][11]13,14]. The likely explanation for this discrepancy is that the fragility data in the present study were normalized to stone size, a procedure that was not done in any of the previous studies.…”

Section: Discussioncontrasting

confidence: 98%

“…Helical computed tomography (CT) has been proposed as a means to predict the success or failure of lithotripsy [6,8], and a number of studies have attempted to utilize CT numbers (in Hounsfield units, which are related to x-ray attenuation values) as a predictor of stone fragility [9][10][11][12][13][14]. However, given the resolution of clinical CT and the effects of volume averaging, the simple measure of Hounsfield units in stones is most likely to correlate with stone size [15,16], and stone size correlates with the number of SW's required for comminution [5].…”

Section: Introductionmentioning

confidence: 99%

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CT visible internal stone structure, but not Hounsfield unit value, of calcium oxalate monohydrate (COM) calculi predicts lithotripsy fragility in vitro

et al. 2007

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COM stones are often resistant to breakage using shock wave (SW) lithotripsy. It would be useful to identify by computed tomography (CT) those COM stones that are susceptible to SW's. For this study, 47 COM stones (4-10 mm in diameter) were scanned with micro CT to verify composition and also for assessment of heterogeneity (presence of pronounced lobulation, voids, or apatite inclusions) by blinded observers. Stones were then placed in water and scanned using 64-channel helical CT. As with micro CT, heterogeneity was assessed by blinded observers, using high-bone viewing windows. Then stones were broken in a lithotripter (Dornier Doli-50) over 2 mm mesh, and SW's counted. Results showed that classification of stones using micro CT was highly repeatable among observers (κ=0.81), and also predictive of stone fragility. Stones graded as homogeneous required 1874±821 SW/g for comminution, while stones with visible structure required half as many SW/g, 912±678. Similarly, when stones were graded by appearance on helical CT, classification was repeatable (κ=0.40), and homogeneous stones required more SW's for comminution than did heterogeneous stones (1702±993 SW/g, compared to 907±773). Stone fragility normalized to stone size did not correlate with Hounsfield units (p=0.85). In conclusion, COM stones of homogeneous structure require almost twice as many SW's to comminute than stones of similar mineral composition that exhibit internal structural features that are visible by CT. This suggests that stone fragility in patients could be predicted using pre-treatment CT imaging. The findings also show that Hounsfield unit values of COM stones did not correlate with stone fragility. Thus, it is stone

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Section: Discussioncontrasting

confidence: 98%

Section: Introductionmentioning

confidence: 99%

CT visible internal stone structure, but not Hounsfield unit value, of calcium oxalate monohydrate (COM) calculi predicts lithotripsy fragility in vitro

et al. 2007

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“…Several in vitro and in vivo studies have shown that this approach can discriminate UA from non-UA stones (7)(8)(9)(10)(11). Combining the analysis of CT numbers with visual assessment of stone morphology using a wide window setting (eg, bone window) substantially improves the accuracy of stone characterization (12).…”

Section: Introductionmentioning

confidence: 99%

Noninvasive Differentiation of Uric Acid versus Non–Uric Acid Kidney Stones Using Dual-Energy CT

et al. 2007

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Rationale and Objectives-To determine the accuracy and sensitivity for dual-energy computed tomography (DECT) discrimination of uric acid (UA) stones from other (non-UA) renal stones in a commercially implemented product.Materials and Methods-Forty human renal stones comprising uric acid (n = 16), hydroxyapatite (n = 8), calcium ox-alate (n = 8), and cystine (n = 8) were inserted in four porcine kidneys (10 each) and placed inside a 32-cm water tank anterior to a cadaver spine. Spiral dual-energy scans were obtained on a dual-source, 64-slice computed tomography (CT) system using a clinical protocol and automatic exposure control. Scanning was performed at two different collimations (0.6 mm and 1.2 mm) and within three phantom sizes (medium, large, and extra large) resulting in a total of six image datasets. These datasets were analyzed using the dual-energy software tool available on the CT system for both accuracy (number of stones correctly classified as either UA or non-UA) and sensitivity (for UA stones). Stone characterization was correlated with micro-CT.Results-For the medium and large phantom sizes, the DECT technique demonstrated 100% accuracy (40/40), regardless of collimation. For the extra large phantom size and the 0.6-mm collimation (resulting in the noisiest dataset), three (two cystine and one small UA) stones could not be classified (93% accuracy and 94% sensitivity). For the extra large phantom size and the 1.2-mm collimation, the dual-energy tool failed to identify two small UA stones (95% accuracy and 88% sensitivity). Conclusions-In an anthropomorphic phantom model, dual-energy CT can accurately discriminate uric acid stones from other stone types. KeywordsKidney stones; renal calculi; dual-energy computed tomography; uric acid; urolithiasis Symptomatic urinary stone disease affects approximately 900,000 persons in the United States each year, resulting in annual medical cost of $5.3 billion. Nephrolithiasis has traditionally been evaluated using plain film radiographic techniques with or without tomography or administration of intravenous contrast for excretory urography. Over recent years, however, computed tomography (CT) has supplanted these traditional techniques because of increased sensitivity, speed, and the lack of intravenous contrast (1 Although state-of-the-art CT provides accurate submillimeter details of the size and location of renal stones (4,5), current routine clinical image analysis does not differentiate stone composition. This is particularly important in the case of uric acid (UA) stones (~10% of cases), because urinary alkalinization can be prescribed to dissolve UA stones and could thereby be initiated at presentation rather than following lengthy metabolic workup. Therefore simple and reliable differentiation of UA versus non-UA stone composition could potentially allow patients with UA stones to avoid invasive interventional urinary procedures for stone removal or external shock wave lithotripsy, both of which are expensive and might result in renal hemorrh...

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“…One month later, patients were reevaluated with KUB or CT. CT was performed when non-opaque stones were present or when evaluation of the stone status was insufficient with KUB. Residual fragments smaller than 3 mm were defined as clinically insignificant residual fragments (CIRF) (8). Larger stones were defined as residual stones.…”

Section: Miniperc Techniquementioning

confidence: 99%

Comparison of efficacy of laser lithotripter with ultrasonic lithotripter in mini percutaneous nephrolithotomy

Akbulut

Küçüktopçu

Kandemir

et al. 2016

Arch Ital Urol Androl

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Objective: The aim of the study was to compare the efficacy of the laser lithotripter with the ultrasonic lithotripter in mini percutaneous nephrolithotomy (miniperc). Material and Methods: From June 2013 to January 2014; medical records of 77 consecutive patients who underwent miniperc operation were retrospectively evaluated. Ultrasonic lithotripter was used in 22 patients (Group 1), while laser was used in 55 patients. In the laser group, 22 patients were randomly selected who had same characteristics compared to group 1 (Group 2). Success rate, total operative time, complications according to modified Clavien classification, fluoroscopy time, haemoglobin drop, hospital stays and cost analysis were assessed. Success rates were evaluated on the second postoperative day and after the first month. Results: Total operative time (p = 0.635) and fluoroscopy time (p = 0.248) were not significantly different between the two groups. In the laser group, the success rate (81.8%) was notably more than in the ultrasonic lithotripter group (68.2%) but there was no statistically significance (p = 0.296). Ten reusable ultrasonic probe were used for 22 patients, due to thinness and sensitiveness of the probe. Conversely, one single laser fiber (550 micron) was used for 22 patients. When the cost analysis of lithotripsy was considered, the cost per case was 190 dollar in group 1 and 124 dollar in group 2. (p = 0.154) Complication rate, hospital stay and haemoglobin drop were similar in both groups. Conclusion: Laser lithotripsy seems to be more cost effective than ultrasonic lithotripsy for miniperc but larger number of patients are required to confirm this estimation. SummaryNo conflict of interest declared. tion (2). In the following years, Jackman et al. used this technique in adult patients (3). Recently published studies underlined that complications like bleeding have declined along with the use of smaller renal access sheaths (4, 5). In a prospective randomized study, the authors suggested that while miniperc and conventional PNL had similar stone clearance rates, complication rate was significantly lower in the miniperc group (6). In the miniperc series, the lithotripter choice is important for stone fragmentation. Laser, pneumatic, and ultrasonic lithotripters are available fragmentation methods for PNL. While pneumatic lithotripsy is the most common technique used for kidney or ureteral stones, stone retropulsion and migration rate is clearly higher compared with other devices. Ganeasomoni et al. compared laser and pneumatic lithotripsy with miniperc and observed that laser lithotripsy group had a lower stone migration rate (7). The ultrasonic lithotripsy enables simultaneous stone fragmentation and aspiration. Low retropulsion rate and absence of the need of stone retrieval are the main advantages of ultrasonic lithotripsy. However, to the best of our knowledge, there is no published study evaluating the efficacy of the ultrasonic lithotripter with miniperc. In this study, we aimed to compare laser lithotripter an...

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Hounsfield Units on Computerized Tomography Predict Stone-Free Rates After Extracorporeal Shock Wave Lithotripsy

Abstract: These findings suggest that HU measurement of urinary calculi on pretreatment non-contrast computerized tomography may predict the stone-free rate. This information may be beneficial for selecting the preferred treatment option for patients with urinary calculi.

Cited by 171 publications

References 12 publications

CT visible internal stone structure, but not Hounsfield unit value, of calcium oxalate monohydrate (COM) calculi predicts lithotripsy fragility in vitro

CT visible internal stone structure, but not Hounsfield unit value, of calcium oxalate monohydrate (COM) calculi predicts lithotripsy fragility in vitro

Noninvasive Differentiation of Uric Acid versus Non–Uric Acid Kidney Stones Using Dual-Energy CT

Comparison of efficacy of laser lithotripter with ultrasonic lithotripter in mini percutaneous nephrolithotomy

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