General
1011 MRCP examinations were done over a period of 20 months for 983 patients,
28 patients had to repeat the examination.
Of the 983 patients,
475 patients were excluded from the study because US has not been done for them.
This resulted in a primary study group of 508 patients for whom both transabdominal US and MRCP were done.
Within the primary study group of 508 patients,
419 patients were again excluded because neither MRCP nor US could reveal choledocholithiasis. The primary study group was,
therefore,
further reduced to a final group of 89 patients (17.5%) in whom choledocholithiasis was diagnosed by MRCP and/or US.
The final study group involved 39 men and 50 women with an age range 20-98 years; mean 66.3 years (table 3).
Table 3: Patient demographics
Total number
Males
Females
Male: female ratio
Median age (year)
|
89
39 (43.8%)
50 (56.2%)
1:1.3
66.31 (range,
20-98)
|
Results of biochemical analysis for those presented as abnormal LFTs is summarized in table 4.
Table 4: Biochemical analysis for patients presented as abnormal LFTs
Test
|
Mean value
|
Range
|
Reference level
|
Bilirubin (µmol/L)*
Alkaline phosphatase (IU/L)
Alanine aminotransferrase (IU/L)
Gamma glutamyl transferrase (IU/L)
Serum amylase (IU/L)
|
15.1
414.1
27.2
317.7
107.5
|
2-101
97-1627
9-1089
28-1220
28-614
|
3-17
95-290
10-45
15-40
25-125
|
* To convert bilirubin from micromoles per liter to milligram per deciliter divide micromoles per liters by 17.1
Using MRCP and ultrasound,
89 patients were found to have choledocholithiasis,
in whom both MRCP and US could concurrently reveal stones in 14 patients (15.7%),
MRCP only (and not US) detected stones in 72 patients (80.8%) and only three patients (3.3%) could be diagnosed by US where MRCP reports were negative (table 5).
Table 5: Performance of MRCP vs.
US
Test results
|
Number of patients
|
Percentage (%)
|
MRCP-positive / US-positive
MRCP-positive / US-negative
MRCP-negative / US-positive
Total
|
14
72
3
89
|
15.7
81
3.3
100
|
Total US-positive
Total MRCP-positive
US detection rate
MRCP detection rate
|
17
86
---
---
|
---
---
19.1
96.6
|
Out of the total 89 patients of the final study group; a total number of 17 patients had their bile duct stones been detected by US versus 86 patients diagnosed by MRCP resulting in a detection rate of 19.1% and 96.6% for US and MRCP respectively.
CBD size determined by US was 10.03mm median; 3-25mm range compared to CBD size determined by MRCP which was 10.07mm median; 4.5-25mm range.
Average stone size detected by US was 7.8mm while MRCP-detected average stone size was very close (7.9mm).
MRCP is by far much better than US in detecting stones in the distal CBD (64 cases) where US is very insensitive to detect stones in this area due to overlying bowel gas (10 cases).
Subgroup analysis
In the subgroup analysis of 72 patients (35 men,
37 women; age range 30-98 years; mean 66.3 years) whose bile duct stones were exclusively diagnosed by MRCP,
stone number,
size and level together with the CBD size were dealt with.
Table 6 shows patient demographics for this subgroup.
Table 6: Patient demographics in the subgroup analysis
Total number
Males
Females
Male: female ratio
Median age (year)
|
72
35 (48.6%)
37 (51.4%)
1:1.06
66.3 (range,
30-98)
|
Regarding stone number,
42 patients were found to harbor a solitary bile duct stone,
15 patients with two stones and 15 patients with more than 2 stones,
table 7 shows the details.
Table 7: Stone number,
subgroup analysis
Number
|
Number of patients
|
Percentage (%)
|
1
2
3
4
>4
|
42
15
2
4
9
|
58.3
20.8
2.7
5.5
12.5
|
Stone size was found to vary greatly,
ranging from 1 to 30 mm with an average of 7.5mm.
25 patients were found to have stones less or equal to 5 mm and 47 patients had stones greater than 5mm in size (table 8).
Table 8: Stone size,
subgroup analysis
Size (mm)
|
Number of patients
|
Percentage (%)
|
≤5
>5
|
25
47
|
34.7
65.2
|
The site of stones within the biliary duct system was found to range between CBD,
right hepatic duct and common hepatic duct with different proportions.
The vast majority of stones were found to be present in the CBD (69 patients) compared to 2 patients having their stones been located in the common hepatic duct and only one patient with a right hepatic duct stone (table 9).
Table 9: Stone level,
subgroup analysis
Level
|
Number of patients
|
Percentage (%)
|
CBD
Proximal
Mid-portion
Distal
Right hepatic duct
Common hepatic duct
2-levels
|
69
3
8
58
1
2
2
|
95.8
4.4
11.6
84
1.4
2.8
2.8
|
The common bile duct status was also studied in this subgroup,
showing that 23 out of the 72 patients (32%) were represented with a non-dilated CBD,
and the remaining 49 patients (68%) had their CBD been dilated,
with a range of 10-25mm and average size of 10.8mm as demonstrated in table 10.
Table 10: Bile duct status
Bile duct status
|
Number of patients
|
Percentage (%)
|
Non-dilated
Dilated
Range (10-25) mm
Average (10.8) mm
|
23
49
|
32
68
|
Table 11: Summery of subgroup analysis results
stone
|
Size (mm)
Number
Single (/patient)
Multiple (/patient)
Location (/patient)
CBD
CHD
Rt.
hepatic duct
2-levels
|
Range,1-30;average,7.5
94*
42**
30***
69
2
1
2
|
CBD
|
Dilated
Non-dilated
|
49
23
|
*For patients having up to 4 stones.
More than 4 stones in the same patient were excluded.
**Number of patients having solitary stone
***Number of patients having more than one stone