In order to campare the difference between clinical diagnosis and B ultrasonic for 120 gallstones patients. Each patient with two kind of Methods for the diagnosis, the results as following: The positive rate of clinical diagnosis is 50%, The positive rate of B ultrasonic is 60%, The positive rate of two methods at the same time is 35%. How to analysis the difference between two methods?

Elsa Brewer 2022-07-22 Answered
In order to campare the difference between clinical diagnosis and B ultrasonic for 120 gallstones patients. Each patient with two kind of Methods for the diagnosis, the results as following: The positive rate of clinical diagnosis is 50%, The positive rate of B ultrasonic is 60%, The positive rate of two methods at the same time is 35%. How to analysis the difference between two methods?
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Answers (1)

Rihanna Robles
Answered 2022-07-23 Author has 18 answers
Ultrasound scanning has been the modality of choice for the clinical diagnosis of gallstone disease for the last 25 years. It is accepted to possess a higher sensitivity than oral cholecystography or computed tomography. Ultrasound technology has undergone a period of maturation. Competition between ultrasound manufacturers and developments in computing have resulted in a significant improvement in image resolution. With such progress in technology, one would assume that the sensitivity of the diagnostic tool would also increase. Meta-analysis of studies between 1966–1992 assessing the diagnosis of biliary disease produced figures of the adjusted sensitivity of ultrasound for the diagnosis of gallstones at 0.84 and a specificity of 0.99. These figures are similar to the figures that we collected nearly 20 years later. The question, therefore, remains as to why it is that, with an increase in ultrasound resolution, there has been no corresponding improvement in sensitivity? Gallstones in the neck of the gallbladder are always difficult to identify due to the area surrounding the neck of the gallbladder being echogenic itself and as the stones cannot move. There is the possibility that stones may be lost during cholecystectomy which accounts for findings. The incidence of spillage of stones is difficult to quantify but varies from figures as low as 3.3% to 17% and non-retrieval of 0.3%. The spillage is most likely to occur during perforation of the gallbladder and is believed to occur in between 8–32% of laparoscopic cholecystectomies. However, we excluded all open specimens excluding the possibility of spillage from our study.

A factor known to limit the accuracy of ultrasonography is body habitus. Studies have suggested a linear increase in habitus limited reports as a result of increasing obesity. With the development of an increasingly obese population, there is a possibility that this may be negating the improvements in ultrasound resolution over the same time period. We did not address this in our study, but it is an area which deserves further investigation.

It is a wide-spread held belief that the performance and interpretation of ultrasonography by a qualified radiologist is more accurate than that performed by an ultrasonographer. However, our study does not support this with a PPV of 0.84 and 0.83 for radiologists and ultrasonographers, respectively. This has implications for the funding of ultrasonography services as there is no evidence that a well-trained ultrasonographer’s report should be inferior to that of a radiologist.

The question arises as to whether we are happy in the 21st century to accept working with a modality that has a sensitivity of 84% or do we wish to progress to something else. Magnetic resonance cholangiopancreatography has been widely accepted for its sensitivity in the diagnosis of choledoclithiasis but has never been proven superior to ultrasound in cholelithiasis. With an increasingly obese population, particular attention may well be warranted to this subgroup and CT cholecystography has shown promising results in small trials but would require further exploration.
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New questions

The Porsche Club of America sponsors driver education events that provide high-performance driving instruction on actual racetracks. Because safety is a primary consideration at such events, many owners elect to install roll bars in their cars. Deegan Industries manufactures two types of roll bars for Porsches. Model DRB is bolted to the car using existing holes in the car's frame. Model DRW is a heavier roll bar that must be welded to the car's frame. Model DRB requires 20 pounds of a special high alloy steel, 40 minutes of manufacturing time, and 60 minutes of assembly time. Model DRW requires 25 pounds of the special high alloy steel, 100 minutes of manufacturing time, and 40 minutes of assembly time. Deegan's steel supplier indicated that at most 40,000 pounds of the high-alloy steel will be available next quarter. In addition, Deegan estimates that 2000 hours of manufacturing time and 1600 hours of assembly time will be available next quarter. The pro?t contributions are $200 per unit for model DRB and $280 per unit for model DRW. The linear programming model for this problem is as follows:
Max 200DRB + 280DRW
s.t.
20DRB + 25DRW 40,000 Steel Available
40DRB + 100DRW ? 120,000 Manufacturing minutes
60DRB + 40DRW ? 96,000 Assembly minutes
DRB, DRW ? 0
Optimal Objective Value = 424000.00000
Variable Value blackuced Cost
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
DRB 1000.00000 0.00000
DRW 800.00000 0.00000
Constraint Slack/ Surplus Dual Value
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
1 0.00000 8.80000
2 0.00000 0.60000
3 4000.00000 0.00000
Objective Allowable Allowable
Variable Coef?cient Increase Decrease
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
DRB 200.00000 24.00000 88.00000
DRW 280.00000 220.00000 30.00000
RHS Allowable Allowable
Constraint Value Increase Decrease
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
1 40000.00000 909.09091 10000.00000
2 120000.00000 40000.00000 5714.28571
3 96000.00000 Infnite 4000.00000
a. What are the optimal solution and the total profit contribution?
b. Another supplier offeblack to provide Deegan Industries with an additional 500 pounds of the steel alloy at $2 per pound. Should Deegan purchase the additional pounds of the steel alloy? Explain.
c. Deegan is considering using overtime to increase the available assembly time. What would you advise Deegan to do regarding this option? Explain.
d. Because of increased competition, Deegan is considering blackucing the price of model DRB such that the new contribution to profit is $175 per unit. How would this change in price affect the optimal solution? Explain.
e. If the available manufacturing time is increased by 500 hours, will the dual value for the manufacturing time constraint change? Explain.