Hounsfield units hu indicate the hardness of renal calculi and identify high density stones to be excluded from shockwave lithotripsy swl 2. Impact of stone density on outcomes in percutaneous. Value of hounsfield unit in prediction of stone free rate in management of upper urinary tract stones using ct and eswl. Pdf the comparative survey of hounsfield units of stone.
A retrospective study was performed to measure stone hu values in 260 patients who underwent extracorporeal shock wave lithotripsy eswl for solitary renal and ureteral stones from july 2007 to january 2012. Combining mean and standard deviation of hounsfield unit. One well known use is the evaluation of the fat content of the liver, with fatty liver diagnosed by the presence of a livertospleen ratio composition of a urinary stone may influence its surgical and medical treatment. Determining the composition of urinary tract calculi using.
Mohammad hammad ather, wasim memon, wajahat aziz and mohammad nasir sulaiman august 9th 2017. This study demonstrated that computed tomography scanning could predict the chemical composition of urinary stones. Factors influencing the duration of urine leakage following percutaneous nephrolithotomy. One well known use is the evaluation of the fat content of the liver, with fatty liver diagnosed by the presence of a livertospleen ratio stone and the overall health of the kidney, ct can also assess the density of the stone in hounsfield units hu. The hu, or hounsfield density, measured by ct, is related to the density of the tissue or stone. For those in whom intervention is warranted, treatment is based on stone characteristics such as chemical composition based on hounsfield units of the stone on ct and patient associated risk factors, intrarenal location, number and size of stones, and upper tract anatomy. For the last few years, attempts have been made to correlate the measurement of stone density in hounsfield units hu with stone composition. What is the role of ct scanning in the assessment of stone. Evaluation of outcome of ureteroscopic pneumatic lithotripsy. The hounsfield scale or ct numbers, named after sir godfrey newbold hounsfield, is a quantitative scale for describing radiodensity. Segura jw, preminger gm, assimos dg, dretler sp, kahn ri, lingeman je, macaluso jn jr.
Evaluation of hounsfield units as a predictive factor for the. The comparative survey of hounsfield units of stone composition in urolithiasis patients parisa sotoodeh shahnani, mehdi karami, bahman astane 1, mohsen janghorbani 2. Uric acid nephrolithias in the era of noncontrast computed. Aug 20, 2014 the objective of this study was to evaluate the utility of the hounsfield unit hu values as a predictive factor of extracorporeal shock wave lithotripsy outcome for ureteral and renal stones. To determine the in vivo ability to predict uric acid stone composition by hounsfield units hu with the addition of urine parameters. Clinical utility of computed tomography hounsfield. A total of 52 patients, who underwent semirigid ureteroscopy and laser lithotripsy for distal ureteral stone and had isochoronous phleboliths in uct, were included.
Differentiation of kidney stones using dualenergy ct with and without a tin filter. A retrospective study was performed to measure stone hu values in 260 patients who underwent extracorporeal. Altan m, citamak b, bozaci ac, gunes a, dogan hs, haliloglu m, tekgul s. The hounsfield unit hu scale is a linear transformation of the original linear attenuation coefficient measurement into one in which the radiodensity of distilled water at standard pressure and temperature is defined as zero hounsfield units hu, while the radiodensity of air at stp is defined as hu. Departments of radiology and 2health, isfahan university of medical sciences, 1department of urology, azad university, isfahan, iran. A number of studies have assessed the use of hu in urology.
Pathology etiology penetrating or nonpenetrating abdominal trauma often with associated organ injury 1 ruptured ectopic pregnancy ovarian cys. The calibration of ct hounsfield units for radiotherapy. Unfavorable composition of the stone is the major factor for failure of swl. Health, general calculi, urinary diagnosis prevention cat scans usage ct imaging urinary stones. Hounsfield units hu provides a quantitative assessment of stone density in the urogenital tract on noncontrast computed tomography ncct and has the ability to predict treatment success. The use of different hu parameters, such as hounsfield density. In recent studies, the data for body mass index bmi, skin stone distance ssd, the stone hounsfield units hu are also considered 5. We aimed to compare density measurements obtained through rdct vs sct and to determine if there is a correlation between stone. Hounsfield arbitrarily assigns water a density of 0 hounsfield units hu and air a value of. Stone density measurements have been used to predict composition and help guide treatment in standard dose ct sct but not in reduced dose ct rdct. Differentiation of kidney stones using dualenergy ct with.
The comparative survey of hounsfield units of stone composition in urolithiasis patients. Hounsfield unit definition of hounsfield unit by the. Reduced dose protocols have recently gained wide acceptance. The data is very useful when identifying structures in a ct scan and must be committed to memory. Usefulness of measuring renal papillae in hounsfield units in stone forming patients. The difference in hu hudiff value was measured on ncct in two patients.
A significant correlation between the stone size and housefield unit values was also demonstrated. Hounsfield units are measured and reported in a variety of clinical applications. Pdf stone size limits the use of hounsfield units for. Hounsfield units provide information not only for the diagnosis of urinary system tumors but also regarding a number of properties of urinary stones. A 970 hounsfield units hu threshold of kidney stone density on non. Innovative physicians at new york urology specialists are among the first urologists in nyc specializing in kidney stone care to use hounsfield units to optimize care for kidney stones in new york city. Because noncontrast computed tomography ct has largely become the imaging of choice for suspected renal colic, several groups have examined attenuation coefficient measurements, as measured in hounsfield units hu, and urinary stone composition. Diagnostic utility of attenuation measurement hounsfield. Noncontrast computed tomography ncct has high sensitivity, specificity, and is able to predict stone composition using hounsfield units hu but is associated with high radiation exposure. The stones were classified as com, calcium oxalate dehydrate or weddellite cod, calcium. By continuing to use this site you consent to the use of cookies on your device as described in our cookie policy unless you have disabled them. Comparing stone attenuation in low and conventionaldose.
A 970 hounsfield units hu threshold of kidney stone. Hounsfield unit hu determination of urinary stones on noncontrast computed tomography ncct has been shown to predict stone composition. Medical express correlation between hounsfield unit. We present latest research on the topic for your reference. However, the scale by its the definition is openended. Hu density hud was calculated by dividing mean hu by the stone s largest transverse diameter.
Computed tomography evaluation of urinary stones densities. We investigate the efficacy of hu measurement on ncct to determine if it can differentiate the various calcium stone subtypes. Hounsfield unit values and renal stone composition silva tr figure 2 probability of a stone being predominantly composed of com or other mineral as calculated by the prediction equation model. An analysis of the clinical research office of the endourological society croes pcnl global study database. The dualenergy ratio of the mean attenuation values of each stone was computed for each protocol. The hounsfield density was a convenient radiographic measure that correlated well with the chemical composition. Hounsfield unit density in the determination of urinary stone composition 1 1 the views expressed in this report are those of the authors and do not reflect the official policy of the department of defense or other departments of the u. Eray hasirci1, mehmet ilteris tekin 1, ayhan dirim1, mehmet resit goren2, mustafa agah tekindal 3, hakan ozkardes1 1department of urology, baskent university faculty of medicine, ankara, turkey 2department of urology, baskent university school of medicine, adana dr. Although this has been difficult due to the wide variability in chemical composition and stone size 6, the use of hu can distinguish between a uric acid and a calcium stone 7, 8, and even between different subtypes of calcium stones 9.
The hounsfield unit density of the calculus on ct scanning can also be useful in predicting whether the stone is composed of uric acid. Hounsfield unit synonyms, hounsfield unit pronunciation, hounsfield unit translation, english dictionary definition of hounsfield unit. May 11, 2015 stone densities can be measured on a ct scan in hounsfield units. Our opinion is that hudiff can predict stone composition before treatment. Table 1 is a simple list of hounsfield units for body tissues identified in a head ct. Developed first practical computed tomography device, the emi scanner.
The hounsfield scale of tissue density is based on two values. However, no in vivo studies have attempted to radiographically separate the various calcium stone compositions. Absolute hounsfield unit measurement on noncontrast. Medical dissolution therapy for kidney stone with low density on noncontrast computed tomography. Predicting the stone composition of children preoperatively by hounsfield unit detection on noncontrast computed tomography. Original research, clinical report by canadian urological association journal cuaj. Hounsfield shared the award with the south africanborn scientist allan m.
Hounsfield unit density in the determination of urinary. Pareek g, armenakas na, fracchia ja 2003 hounsfield units on computerized tomography predict stone free rates after extracorporeal shock wave lithotripsy. Several in vitro studies have demonstrated the utility of ct in predicting stone composition 3,4,5,6. We investigated whether stone heterogeneity index shi, which a proxy of such variations, was defined as the standard deviation of a hounsfield unit hu on. Value of hounsfield unit in prediction of stone free rate.
The predominant chemical stone composition was recorded for every patient, and the respective hus were compared. Instead of googling, you should first read and try to understand the only reference that is relevant in this context. The role of computed tomography findings in prediction of. Parisa sotoodeh shahnani, mehdi karami, bahman astane1, mohsen janghorbani2. Usefulness of measuring renal papillae in hounsfield units. For the purpose of the article, the terms urolithiasis, nephrolithiasis, and renalkidney stones are used interchangeably, although some authors have slightly varying definitions of each. Renal calculi composition hounsfield units or dual. Even though they appear to be clinical factors, bmi and ssd are physical characteristics of conditions associated with lithotripsy. Noncontrast computed tomography ncct is the diagnostic choice for renal stone disease. The mean stone attenuation was 337 hounsfield units hu from the crosssectional imaging, which suggested the presence of a uric acid stone. Noncontrast ct in the evaluation of urinary tract stone. Required if the rescale type is not hu hounsfield units. Extracorporeal shock wave lithotripsy success based on body mass index and hounsfield units.
Hounsfield units on computed tomography predict calcium. The comparative survey of hounsfield units of stone composition in urolithiasis patients article pdf available in journal of research in medical sciences 197. Author links open overlay panel gregory stewart a lewis johnson a halemane ganesh b daniel davenport c woodson smelser a paul crispen a ramakrishna venkatesh a. Using hounsfield unit measurement and urine parameters to. We also assessed the possibility that hu values could be used to predict stone composition. Surgical management of upper urinary tract calculi. Urolithiasis refers to the presence of calculi anywhere along the course of the urinary tracts. We retrospectively evaluated patients who had stone analysis, ncct images, and underwent percutaneous nephrolithotomy between 20 and 2016. If stone removal is planned and this is almost always the case in patients with iis a contrast study is necessary as the anatomy of the collecting system and renal function have to be assessed le 3. The predominant composition of the stones defined their primary group. Use of hounsfield units to optimize care for kidney stones. Are hounsfield densities of ureteral stones a predictive. Evaluation of hounsfield units as a predictive factor for. The range of stone density for kidney stones is between 4001,400hfu.
Impact of stone density on outcomes in percutaneous nephrolithotomy pcnl. What is the meaning of a hounsfield number of 12 given to a. Peak kilo voltage output of the xray generator used. Computed tomography is currently used most commonly to predict the type of stone and assess the potential efficacy of extracorporeal shock wave lithotripsy treatment.
Hounsfield unit definition of hounsfield unit by the free. Specifies the output units of rescale slope 0028,1053 and rescale intercept 0028,1052. Normally, these values are stored in the dicom file itself. Digital scout film left and ct scan right of a 79yearold woman showing a 2. Stone volume, location, skinto stone distance, stone hu values, and stone composition. The comparative survey of hounsfield units of stone.
The hounsfield scale named for one of the nobel prizewinning inventors of ct, the british physicist godfrey n. We aimed to evaluate the additional use of standard deviation of hu husd to more accurately predict stone composition. Hounsfield units scale of hu, ct numbers classifications. Several in vitro studies have demonstrated the utility of ct in predicting stone composition 36. As the density of the stone approaches 1,000hfu, the stone becomes harder to break and may require 2 treatments. Hounsfield units hu indicate the hardness of renal calculi and identify high density stones to be excluded from shockwave lithotripsy swl. To obtain this relationship we have calculated the relative electron densities of various tissue substitutes icru 1989, constantinou 1974 taking into account their chemical composition tables 1 and 3. Computed tomography ct is the gold standard for the preoperative study of stones and influences the choice of surgical strategy. Omer m a e, abdelazim h k, faisal y a, tarig h h a. Clearly, in patients with prior urolithiasis, stone composition analysis is. Value of hounsfield unit in prediction of stone free rate in. Noncontrast ct in the evaluation of urinary tract stone obstruction and haematuria, computed tomography advanced applications, ahmet mesrur halefoglu, intechopen, doi. Stone size limits the use of hounsfield units for prediction of calcium oxalate stone composition.
Previous attempts at identifying stone composition based on mean hounsfield units hum have had varied success. Can the hounsfield unit predict the success of medically expulsive therapy. Hounsfield unit density in the determination of urinary stone. Pareek g, armenakas na, panagopoulos g, bruno jj, fracchia ja. Correlation between hounsfield unit value and stone. Objective1 to determine the best cutoff level of hounsfield units hu in the ct stonogram that would predict the appearance of a urinary calculi in plain kub xray. In addition, the attenuation value of calculi on computed tomography, measured in hounsfield units hus. Recent in vitro studies have suggested that ncct can be used to predict the composition of urinary stones on the basis of differences in radiodensity measured in hounsfield units, hus. Hounsfield number definition of hounsfield number by. Hounsfield units can be used to characterise renal stones, with a uric acid stone having a lower hounsfield unit than a calcified stone.
Hounsfield unit article about hounsfield unit by the free. Extracorporeal shock wave lithotripsy success based on. A calculus hu is more likely to be calcium and hounsfield unit values and renal stone composition silva tr the stones were analyzed by infrared spectrophotometry louis c. In addition to the size and location of the stone and the overall health of the kidney, ct can also assess the density of the stone in hounsfield units hu. Inclusion criteria were ncct prior to stone analysis and stone size. Hounsfield unit density was calculated to determine urinary stone composition, as described previously 8. Specific changes in attenuation hounsfield units hu between high and lowenergy spectra allow dect to differentiate between materials containing similar electron densities but differing photon absorption. In an attempt to reduce radiation exposure, lowdose stone protocols have been developed that provide excellent detection of stones. Can the hounsfield unit predict the success of medically. Does the hounsfield unit value determined by computed. The purpose of the study was to investigate the predictive value of stone measurements by including a novel method on noncontrast computed tomography ncct images for stone composition. Jan 15, 2010 what is the meaning of a hounsfield number of 12 given to a cyst on a kidney answered by a verified doctor we use cookies to give you the best possible experience on our website. To evaluate the outcome of ureteroscopic pneumatic lithotripsy in single lower ureteric calculus and correlate its success with different ct parameters like hu, size of calculus and hydrnephrosis, if present. Medical dissolution therapy for kidney stone with low.
Stone size limits the use of hounsfield units for prediction of calcium oxalate stone composition article pdf available in urology 852 december 2014 with 250 reads how we measure reads. The tags are generally called the rescale slope and rescale intercept, and typically have values of 1 and 1024, respectively. Lowdose ct scan in stone detection for stone treatment. However, resolution also suffers in regard to stone composition measurement of hounsfield units. Hounsfield definition of hounsfield by medical dictionary. Computed tomography ct is widely used to examine stones in the urinary system. A novel method for prediction of stone composition. Nov 06, 2014 hounsfield units hu, a parameter generated from standard ct, are related to the density of the stone or structure of interest.
Hounsfield units hu, a parameter generated from standard ct, are related to the density of the stone or structure of interest. Sep 16, 2016 to differentiate ureteral stones and phleboliths by measuring density as hounsfield unit hu and volume as mm3 of the opacities in the bony pelvis on unenhanced computerized tomography uct. The objective of this study was to evaluate the utility of the hounsfield unit hu values as a predictive factor of extracorporeal shock wave lithotripsy outcome for ureteral and renal stones. Knowing the composition of a stone before passage can help to choose a better management. Methodsa prospective crosssectional study of patients aged 1885. Noncontrast computed tomography ncct has emerged as the diagnostic study of choice in the evaluation of acute flank pain. Hounsfield unit density in the determination of urinary stone composition 1 1 the views expressed in this report are those of the authors and do not reflect the official policy of the department. Sir godfrey newbold hounsfield first introduced the principle to quantify the amount of xrays that pass through or are absorbed by tissues, and developed the resulting radiodensity scale. Given that noncontrast computed tomography ncct has become the gold standard of diagnosing urinary stones 10,11, many groups have focused on the relation between hounsfield units hu, especially mean stone density msd, and urinary stone composition or treatment outcome. We sought to determine whether the hounsfield unit hu measured by ncct can predict the composition.
451 619 862 48 1643 911 1676 1034 383 1649 1274 141 613 62 582 58 1095 1296 1255 1033 611 1253 354 615 1371 1615 277 1288 1395 1057 1503 238 1046 74 1438 139 346 990 1470 840 1278 324 966 1062