The predominant chemical stone composition was recorded for every patient, and the respective hus were compared. Clearly, in patients with prior urolithiasis, stone composition analysis is. 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. Evaluation of hounsfield units as a predictive factor for. Hounsfield unit definition of hounsfield unit by the. Our opinion is that hudiff can predict stone composition before treatment. Methodsa prospective crosssectional study of patients aged 1885. Comparing stone attenuation in low and conventionaldose. 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. Pareek g, armenakas na, fracchia ja 2003 hounsfield units on computerized tomography predict stone free rates after extracorporeal shock wave lithotripsy. Medical dissolution therapy for kidney stone with low density on noncontrast computed tomography. 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.
Computed tomography evaluation of urinary stones densities. Hounsfield units can be used to characterise renal stones, with a uric acid stone having a lower hounsfield unit than a calcified stone. For the last few years, attempts have been made to correlate the measurement of stone density in hounsfield units hu with stone composition. 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. 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.
Hounsfield units hu indicate the hardness of renal calculi and identify high density stones to be excluded from shockwave lithotripsy swl 2. Pareek g, armenakas na, panagopoulos g, bruno jj, fracchia ja. Surgical management of upper urinary tract calculi. Mohammad hammad ather, wasim memon, wajahat aziz and mohammad nasir sulaiman august 9th 2017. Hounsfield units are measured and reported in a variety of clinical applications. 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. Hounsfield definition of hounsfield by medical dictionary. Are hounsfield densities of ureteral stones a predictive. Noncontrast computed tomography ncct is the diagnostic choice for renal stone disease. 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. The stones were classified as com, calcium oxalate dehydrate or weddellite cod, calcium.
Evaluation of hounsfield units as a predictive factor for the. 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. A total of 52 patients, who underwent semirigid ureteroscopy and laser lithotripsy for distal ureteral stone and had isochoronous phleboliths in uct, were included. Pathology etiology penetrating or nonpenetrating abdominal trauma often with associated organ injury 1 ruptured ectopic pregnancy ovarian cys. Hounsfield unit hu determination of urinary stones on noncontrast computed tomography ncct has been shown to predict stone composition.
Differentiation of kidney stones using dualenergy ct with and without a tin filter. Nov 06, 2014 hounsfield units hu, a parameter generated from standard ct, are related to the density of the stone or structure of interest. Extracorporeal shock wave lithotripsy success based on. 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. We investigate the efficacy of hu measurement on ncct to determine if it can differentiate the various calcium stone subtypes. We present latest research on the topic for your reference. Correlation between hounsfield unit value and stone. Required if the rescale type is not hu hounsfield units. Stone size limits the use of hounsfield units for prediction of calcium oxalate stone composition. However, resolution also suffers in regard to stone composition measurement of hounsfield units. An analysis of the clinical research office of the endourological society croes pcnl global study database.
A 970 hounsfield units hu threshold of kidney stone. Differentiation of kidney stones using dualenergy ct with. 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. The comparative survey of hounsfield units of stone composition in urolithiasis patients. Hounsfield unit synonyms, hounsfield unit pronunciation, hounsfield unit translation, english dictionary definition of hounsfield unit. Hounsfield units provide information not only for the diagnosis of urinary system tumors but also regarding a number of properties of urinary stones. Hounsfield unit density in the determination of urinary stone. Noncontrast ct in the evaluation of urinary tract stone obstruction and haematuria, computed tomography advanced applications, ahmet mesrur halefoglu, intechopen, doi. Evaluation of outcome of ureteroscopic pneumatic lithotripsy. Value of hounsfield unit in prediction of stone free rate in. We retrospectively evaluated patients who had stone analysis, ncct images, and underwent percutaneous nephrolithotomy between 20 and 2016.
Hounsfield unit density in the determination of urinary. Segura jw, preminger gm, assimos dg, dretler sp, kahn ri, lingeman je, macaluso jn jr. 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. The hounsfield unit density of the calculus on ct scanning can also be useful in predicting whether the stone is composed of uric acid.
Impact of stone density on outcomes in percutaneous nephrolithotomy pcnl. Does the hounsfield unit value determined by computed. 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. Hounsfield unit definition of hounsfield unit by the free. The comparative survey of hounsfield units of stone composition in urolithiasis patients article pdf available in journal of research in medical sciences 197. 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. Peak kilo voltage output of the xray generator used. Uric acid nephrolithias in the era of noncontrast computed. Hounsfield arbitrarily assigns water a density of 0 hounsfield units hu and air a value of. The use of different hu parameters, such as hounsfield density. Parisa sotoodeh shahnani, mehdi karami, bahman astane1, mohsen janghorbani2.
Previous attempts at identifying stone composition based on mean hounsfield units hum have had varied success. Impact of stone density on outcomes in percutaneous. Hounsfield units hu indicate the hardness of renal calculi and identify high density stones to be excluded from shockwave lithotripsy swl. Medical dissolution therapy for kidney stone with low. What is the meaning of a hounsfield number of 12 given to a. Determining the composition of urinary tract calculi using.
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. Several in vitro studies have demonstrated the utility of ct in predicting stone composition 36. Hounsfield shared the award with the south africanborn scientist allan m. Hounsfield unit article about hounsfield unit by the free. Use of hounsfield units to optimize care for kidney stones.
Hounsfield units hu, a parameter generated from standard ct, are related to the density of the stone or structure of interest. Computed tomography is currently used most commonly to predict the type of stone and assess the potential efficacy of extracorporeal shock wave lithotripsy treatment. The comparative survey of hounsfield units of stone. 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. 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. 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.
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. The predominant composition of the stones defined their primary group. Renal calculi composition hounsfield units or dual. Hounsfield units for predicting eswl and stone composition. A number of studies have assessed the use of hu in urology. The data is very useful when identifying structures in a ct scan and must be committed to memory. The role of computed tomography findings in prediction of. Value of hounsfield unit in prediction of stone free rate in management of upper urinary tract stones using ct and eswl.
Lowdose ct scan in stone detection for stone treatment. Combining mean and standard deviation of hounsfield unit. The tags are generally called the rescale slope and rescale intercept, and typically have values of 1 and 1024, respectively. The hounsfield scale named for one of the nobel prizewinning inventors of ct, the british physicist godfrey n. Specifies the output units of rescale slope 0028,1053 and rescale intercept 0028,1052.
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. Computed tomography ct is the gold standard for the preoperative study of stones and influences the choice of surgical strategy. Urolithiasis refers to the presence of calculi anywhere along the course of the urinary tracts. Inclusion criteria were ncct prior to stone analysis and stone size. Noncontrast ct in the evaluation of urinary tract stone. We aimed to compare density measurements obtained through rdct vs sct and to determine if there is a correlation between stone. The dualenergy ratio of the mean attenuation values of each stone was computed for each protocol. 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. 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. Hu density hud was calculated by dividing mean hu by the stone s largest transverse diameter. What is the role of ct scanning in the assessment of stone. Using hounsfield unit measurement and urine parameters to. A 970 hounsfield units hu threshold of kidney stone density on non.
We also assessed the possibility that hu values could be used to predict stone composition. The comparative survey of hounsfield units of stone composition in urolithiasis patients parisa sotoodeh shahnani, mehdi karami, bahman astane 1, mohsen janghorbani 2. We sought to determine whether the hounsfield unit hu measured by ncct can predict the composition. Hounsfield units scale of hu, ct numbers classifications. The hounsfield density was a convenient radiographic measure that correlated well with the chemical composition. Even though they appear to be clinical factors, bmi and ssd are physical characteristics of conditions associated with lithotripsy. Absolute hounsfield unit measurement on noncontrast. Altan m, citamak b, bozaci ac, gunes a, dogan hs, haliloglu m, tekgul s.
Original research, clinical report by canadian urological association journal cuaj. 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. Pdf stone size limits the use of hounsfield units for. 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. Noncontrast computed tomography ncct has emerged as the diagnostic study of choice in the evaluation of acute flank pain. 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. The range of stone density for kidney stones is between 4001,400hfu. The hu, or hounsfield density, measured by ct, is related to the density of the tissue or stone. Omer m a e, abdelazim h k, faisal y a, tarig h h a. The calibration of ct hounsfield units for radiotherapy. Value of hounsfield unit in prediction of stone free rate.
Can the hounsfield unit predict the success of medically expulsive therapy. Predicting the stone composition of children preoperatively by hounsfield unit detection on noncontrast computed tomography. To determine the in vivo ability to predict uric acid stone composition by hounsfield units hu with the addition of urine parameters. 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. A novel method for prediction of stone composition. 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. Extracorporeal shock wave lithotripsy success based on body mass index and hounsfield units. Unfavorable composition of the stone is the major factor for failure of swl. Hounsfield number definition of hounsfield number by. The difference in hu hudiff value was measured on ncct in two patients.
Knowing the composition of a stone before passage can help to choose a better management. Several in vitro studies have demonstrated the utility of ct in predicting stone composition 3,4,5,6. May 11, 2015 stone densities can be measured on a ct scan in hounsfield units. In addition, the attenuation value of calculi on computed tomography, measured in hounsfield units hus. 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.
We aimed to evaluate the additional use of standard deviation of hu husd to more accurately predict stone composition. Table 1 is a simple list of hounsfield units for body tissues identified in a head ct. Departments of radiology and 2health, isfahan university of medical sciences, 1department of urology, azad university, isfahan, iran. In recent studies, the data for body mass index bmi, skin stone distance ssd, the stone hounsfield units hu are also considered 5.
This study demonstrated that computed tomography scanning could predict the chemical composition of urinary stones. Usefulness of measuring renal papillae in hounsfield units in stone forming patients. Medical express correlation between hounsfield unit. Computed tomography ct is widely used to examine stones in the urinary system. 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. 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. Usefulness of measuring renal papillae in hounsfield units. 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.1177 118 1441 545 69 1598 723 1610 923 548 1232 739 1369 1223 45 1303 1008 1392 594 227 177 488 969 115 81 1197 550 1673 1091 755 535 794 1636 198 1548 1152 1320 665 488 213 595 491 994 1205 532 1463 1360 1317 275