Shashi B Paul1, Manorama Berry1, Rakesh K Tandon2
1 Department of Radiodiagnosis, All India Institute of Medical Sciences, New Delhi-110029, India
2 Department of Gastroentrology, All India Institute of Medical Sciences, New Delhi-110029, India
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| Abstract|| |
Objectives : To study the ultrasound morphology of cholesterol calculi in Indian patients.
Material and Methods : Twenty-seven patients of solitary gall stones were subjected to ultrasound. The sonographic morphology was categorized into five patterns. Stones obtained at surgery were subjected to estimation of cholesterol content.
Results : All the stones showed cholesterol content of more than 70 gm %, hence were labeled as cholesterol calculi. Five sonographic patterns were documented (full moon 25.9%, half moon 25.9%, crescent 22.2%, comet tail 11.1%, no distinct pattern 14.8%).
Conclusion : Cholesterol gallstones exhibit a heterogeneous sonographic appearance and fall into five distinct sub-types. Classification of patients into these sub-types may have a bearing on management.
Keywords: Gallstones, Cholesterol stones, Ultrasound morphology, Ultrasound sub-types
|How to cite this article:|
Paul SB, Berry M, Tandon RK. Sonographic sub-types of cholesterol gallstones among Indian patients : An initial experience. Indian J Radiol Imaging 1999;9:9-11
Gall stone disease is a relatively common problem in our country particularly in North India. It is estimated that more than sixty percent of these patients have cholesterol stones . US is the modality of choice for diagnosing gall stones. A gall stone on US presents as an echogenic lesion in the dependent part of the gall bladder lumen, moving with change in the position of the patient and exhibiting posterior acoustic shadowing ,.
|How to cite this URL:|
Paul SB, Berry M, Tandon RK. Sonographic sub-types of cholesterol gallstones among Indian patients : An initial experience. Indian J Radiol Imaging [serial online] 1999 [cited 2020 Apr 10];9:9-11. Available from: http://www.ijri.org/text.asp?1999/9/1/9/28362
The variable response of cholesterol calculi to oral dissolution drugs and extra-corporeal shock wave lithotripsy is well known ,,. This is due to differences in their density, composition and distribution of non-cholesterol constituents. Since US images also depend on the composition of the object, it is logical to postulate that different gallstones may have different sonographic characteristics when studied in finer detail. Indeed, Japanese workers have described sub-types of cholesterol stones on ultrasound ,. The present study was undertaken to evaluate the detailed ultrasonographic morphology of cholesterol gallstones among Indian patients.
| Materials & Methods|| |
Twenty-seven symptomatic patients with solitary gallstones attending the out-patient clinics were subjected to US a week prior to surgery (laparoscopic or open cholecystectomy). Ultrasound was performed in the fasting state using a 3.5 MHz transducer (ATL, Ultramark 9 HDI, USA). An attempt was made to profile the calculus fully and delineate the acoustic shadowing clearly. Adapting the classification of Tsuchiya et al  and based on our pilot experience, the sonographic morphology of the stones was categorized into five sub-types, namely: (i) full moon, (ii) half moon (iii) crescent (iv) comet tail (v) others. The schematic drawings of the first four subtypes are shown in [Figure - 1]. The sonographic echopattern and the shadowing of the fifth subtype of 'others' showed bizarre appearances and could not be classified into any of the other four well-defined categories.
Chemical analysis of stones
Calculi of these patients obtained at surgery were subjected to biochemical analysis to estimate their cholesterol content. A stone with a cholesterol content of more than 70 gm percent was classified as a cholesterol calculus.
| Results|| |
The average age of the patients was 38.7 years (range 22-74 years) with a man: woman ratio of 2:7. On analysis, all the 27 gallstones were proven to be cholesterol calculi.
The prevalence of the various sonographic sub-types is depicted in the Table. Full moon, half moon and crescent varieties were commonly encountered, while the comet tail pattern was seen relatively less frequently. Representative ultrasound pictures of different types of stones are shown in [Figure - 2].
| Discussion|| |
It is evident from this study that cholesterol gallstones do not exhibit a uniform sonographic appearance, but have a variety of distinct patterns. The traditional description of a gallstone is that of an echogenic focus with posterior acoustic shadowing ,. The character of the shadowing helps us categorize cholesterol stones into distinct sub-types. Tsuchiya et al  described three sub-types of sonographic morphology (namely comet, half moon and crescent). Other workers have described two additional sonographic patterns, namely sonolucent and irregular ,. The description of these patterns is akin to our classification of full moon and others, respectively.
In the present study, full moon, half moon and crescent varieties were almost equally common, while the comet tail pattern was much less frequently documented. There is evidence that the comet tail variety of cholesterol stones is more susceptible to oral dissolution drugs and extracorporeal shock wave lithotripsy ,. Further investigations are required to confirm whether patients harboring other types of stones (these instances are more common), are less likely to be benefited from these modalities of treatment. This issue needs to be settled through a well-designed clinical trial and our observations from this initial study could form the basis for further evaluation.
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Department of Radiodiagnosis, All India Institute of Medical Sciences, New Delhi-110029
Source of Support: None, Conflict of Interest: None
[Figure - 1], [Figure - 2]