2Department of Paediatric and Neonatal Surgery, Skims, Srinager, Jammu and Kashmir, India
3Department of Radio diagnosis and imaging Skims Srinager, Jammu and Kashmir, India
4Department of Gastroenterology Skims Srinager, Jammu and Kashmir, India
Aims and objectives: The purpose of this study was to determine whether MRCP is feasible in paediatric age group patients and to look for the possible measures to optimize the pediatric MRI. Furthermore, we calculated sensitivity, specificity and accuracy of this test by comparing the results of this test with those of surgery and intra-operative cholangiogram (IOC).
Material and Methods: This study was a prospective and descriptive study between Oct - 2012 to Jan- 2015. We examined 50 consecutive children (28 boys and 22 girls), who were suspected of having pancreaticobiliary disease. Besides base line sonography, MRCP was performed in all patients. The findings of MRCP were compared with those of intraoperative cholangiography (IOC). HIDA was done in 20 patients with neonatal cholestsis and these results were also compared with IOC.
Results: A total of 50 children (7 neonates, 17 infants and 26 older children), 30 children with ductal dilatation and 20 children with cholestatic jaundice. The sensitivity, specificity and accuracy of MRCP were 50%, 75% and 60% respectively in detecting the APBD-union in our series. The sensitivity, specificity, accuracy, Positive predictive value and Negative predictive value of MRCP were 84.61%, 85.71% and 85%, 91.66% and 75% respectively in detecting biliary atresia. For patients with neonatal cholestasis, biliary atresia was excluded if there was visualization of normalextra-hepatic biliary system at MR cholangiography. The sensitivity ,specificity ,positive predictive valve ,negative predictive valve and accuracy of 99mTc-HIDA was 69.23%, 71.42%, 81.8%, 61.1% and 70% respectively. Sedation was required in patients in infants in 10 instances for an optimal MRCP in children. Out of 24 patients having age < 1 year, oral Trichlorphos @ 50-100 mg/Kg was required in 6 instances and intravenous diazepam was needed in 4 patients.
Conclusion: MRCP is effective in delineated choledochal cyst type, and helpful in diagnosing related pancreaticobiliary anomalies, such as APBD–union. But more evaluation needs to be done to assess the MRCP ability to detect APBD –union. Furthermore from our preliminary results, we can conclude that BA can be ruled out if complete extrahepatic bile duct (EHBD) is delineated on MRCP .If EHBD is partially visualized, BA cannot be ruled out because atresia may involve only one part of EHBD. Non – visualization of entire EHBD is suggestive but is not synonymous of BA.
Key Words: Choledochal Cyst (CDC); Anomalous Pancreaticobiliary Ductal Union (APBD union); Magnetic resonance cholangiopancreaticography (MRCP); Intra-operative cholangiogram (IOC)1>
The purpose of this study was to determine whether MRCP is feasible in paediatric age group patients and to look for the possible measures to optimize the pediatric MRI. Furthermore, we calculated sensitivity, specificity and accuracy of this test by comparing the results of this test with those of surgery and intraoperative cholangiogram (IOC).
In patients aged 6 years and below, we used ‘‘sleep debt technique’’ devised by us, wherein parents were advised to discourage early sleeping and late rising of the child on the night preceding the MRI examination ;this resulted in a significant sleep debt of 4 to 5 hours . On the next day, the child was provided milk /breast feed in the MRI suite and was encouraged to go to sleep which helped enough to allow an interrupted MR examination. Children between 6 months to 6 years were sedated with oral Trichlorphos (50-100mg/Kg/body weight and children< 6 months were sedated by intravenous injection of Midazolam 0.5mg/Kg/ body weight when required.
Magnetic resonance cholangiopancreaticography (MRCP) was performed using Fourier acquisition with single shot turbo spin echo (HASTE) sequences. All images were acquired without breath holding. Aware of results of sonography, we initially performed HASTE- sequence MRCP with acquisition of single slice at a slice thickness of 20-25 mm. MRCP at a thinner slice thickness of 3-5 mm was then performed in all patients to examine the details of response of interest. In all patients, coronal and oblique projections were acquired. The total imaging time for all examinations was within 15 minutes.
MRCP demonstrated the type of anomalous pancreaticobiliary ductal union (APBD-union) in 12 patients with age range between 2-10 Years and mean age of 5.99 ± 2.374). In 9 of these 12 patients, the anomalous pancreaticobiliary ductal union revealed by MRCP was concordant with those identified by surgery / intra-operative cholangiography. In 3 patients, the anomalous pancreaticobiliary ductal union could not be confirmed by surgery/intra-operative cholangiography (IOC) probably because of poor image qualities or non opacification of the pancreatic duct. MRCP did not reveal anomalous pancreaticobiliary ductal union in 18 patients who had age range between 6 months -12 years ( mean age3.22 ± 2.67) had markedly dilated choledochal cyst (Type-I - 11 patients and Type-IV - 7 patients ). Out of 18 patients in whom MRCP findings were not suggestive of APBD-union, 9 of these patients, the anomalous pancreaticobiliary ductal union was confirmed by IOC (4-Type -I; 5—Type-IV), after resection of the choledochal cyst. In the remaining 12 patients IOC/surgery failed to depict the anomalous pancreaticobiliary ductal union.
Sensitivity, specificity and accuracy of MRCP in delineating anomalous pancreaticobiliary ductal union were 50%, 75% and 60% respectively. Positive predictive value (PPV) of MRCP in delineating anomalous pancreaticobiliary ductal union 75%. Negative predictive value (NPV) of MRCP in delineating anomalous pancreaticobiliary ductal union was 50 %. APBD -union was revealed in 8 patients with Type- I CDC whereas this union was not visible in 8 patients with Type –IV-a CDC. IOC revealed anomalous pancreaticobiliary ductal union in 18 patients only. Mean ALP level in our CDC patients was 98.84 IU/l with a range of 35-300 IU/L. In our study average size of CDC was 3.290 cm ± 0.514cm (range 1.6-10cms).
Twenty neonates and infants who had neonatal cholestatic jaundice were included in this study. Age range was between 20 days and 76 days, with a mean age of 46.45± 15.65 days. They included 13 males and 7 female neonates and infants. (Table: 10) There were 13 male and 7 female babies. The mean GGT levels were 226.85u/L with a range between 20-543 u/L. Average sizes of GB was 2.39 ± 1.9 cms (range 0.8-4.3 cms). IHD was seen in 11 cases, CHD in 8 and CBD in 8 babies. The overall diagnostic accuracy was 50%.
In our study 99mTc -HIDA scan was performed in all the cases of neonatal cholestasis of infancy. In all cases of EHBA, findings were confirmed on laparotomy and intra- operative cholangiography. Two patients were diagnosed by IOC/ Surgical exploration as having Type- I biliary atresia; in which the distal bile duct was atretic and the common hepatic duct, gallbladder, and cystic duct were normal. Three patients were diagnosed by IOC, Surgical exploration as having Type -II biliary atresia; in which the common hepatic duct was atretic at different levels, whereas the common bile duct, cystic duct, and gallbladder were patent or atretic. Eight patients were diagnosed by IOC/Surgical exploration as having Type -III biliary atresia; in which the entire extrahepatic biliary system, including the common hepatic duct, gallbladder, and common bile duct, was atretic.
Of the 12 patients whose MRCP findings were interpreted as having biliary atresia, 7 patients were confirmed as to have EHBA by intra-operative cholangiography (IOC)/ surgical exploration and 5 patients were confirmed as having no features of BA. Of the 8 patients whose MRCP findings were not consistent with EHBA. IOC/ Surgical exploration was used as the diagnostic gold standard for BA. The sensitivity, specificity, accuracy, positive predictive value (PPV), negative predictive value (NPV) of the MRCP was 84.61%, 85.71%, 85 %, 91.66% and 75 % respectively. [Table 1 ], [Table 2 ], [Table 3 ], [Table 4 ], [Table 5 ], [Table 6 ], [Table 7 ], [Table 8 ], [Table 9 ], [Table 10 ], [Table 11 ] and [Figure1], [Figure2], [Figure 3], [Figure 4], [Figure 5], [Figure6], [Figure 7], [Figure 8], [Figure 9], [Figure 10], [Figure 11].
Group |
Number |
Percentage |
0-6 months |
2 |
6.66 |
7 - 12 months |
2 |
6.66 |
13 months - 2 years |
4 |
13.33 |
2 years-5 years |
14 |
46.66 |
6 years-10 years |
7 |
23.33 |
>10 years |
1 |
3.33 |
Total |
30 |
100 |
Total no of patients included in the study |
50 |
|
Patients with ductal abnormalities |
43 |
|
CDC (n=30) |
CDC with APBD- union |
18 |
CDC without APBD –union |
12 |
|
Infantile Cholestasis (IC) (n=20) |
EHBA |
13 |
Cholestasis due to causes other than EHBA |
7 |
MRCP |
IOC/Surgery |
P- value |
|
CDC |
(100%) 30/30 |
(100%) 30/30 |
- |
APBD –union |
(40%) 12/30 |
(60%) 18/30 |
0.121 |
Biliary atresia |
(60%) 12/20 |
(65.00%) 13/20 |
0.744 |
Cholestasis due to causes other than EHBA |
(40.00%) 8/20 |
(35%) 7/20 |
0.744 |
Type of CDC |
Number |
Percentage |
Type- IV |
6 |
20 |
Type –I |
24 |
80 |
Total |
30 |
100 |
|
MRCP |
Total Count |
||
IOC /SURGERY |
|
APBD-union |
No-APBD-union |
|
APBD-union |
9 |
9 |
18 |
|
No-APBD-union |
3 |
9 |
12 |
|
Total Count |
|
12 |
18 |
30 |
Range (days) |
Number |
Percentage |
20-30 |
4 |
20 |
31-40 |
3 |
15 |
41-50 |
5 |
25 |
51-60 |
3 |
15 |
61-70 |
4 |
20 |
71-80 |
1 |
5 |
Total |
20 |
100 |
Range (u/l) |
Number |
Percentage |
0-100 |
6 |
20 |
101-200 |
4 |
13.33 |
201-300 |
5 |
16.33 |
301-600 |
5 |
16.33 |
Total |
20 |
100 |
Duct |
Visible |
Invisible |
IHD |
11 |
9 |
CHD |
8 |
12 |
CBD |
8 |
12 |
|
IOC /Surgery as Gold Standard |
Count |
||
Ultrasonography |
|
Features of Biliary atresia |
No features of Biliary atresia |
|
BA |
9 |
6 |
15 |
|
No features of BA |
4 |
1 |
5 |
|
Count |
|
13 |
7 |
20 |
Classification of Biliary Artesia |
Description |
No |
|
Type –A |
Type –III |
Entire extrahepatic central biliary ducts (right, left, and common hepatic ducts) and common bile duct were not visible |
8 |
Type –B |
Type –II |
Common hepatic duct was not visible, whereas the common bile duct, cystic duct, and gallbladder were visible |
3 |
Type –C |
Type –I |
Distal bile duct was atretic and CHD, GB, cystic duct were normal |
2 |
|
MRCP |
Count |
||
IOC /SURGERY |
|
Biliary atresia |
No features Biliary atresia |
|
Biliary atresia |
11 |
2 |
13 |
|
No features of Biliary atresia |
1 |
6 |
7 |
|
Count |
|
12 |
8 |
20 |
Mean age of presentation in CDC patients was 4.42 ± 2.43 range 6 months – 12 years, WHICH WAS similar to reported by authors like Todani et al and de Vries et al [5,6]. Most common presentation of CDC in our series was pain abdomen in 16 (53.33%) cases followed by pain abdomen with jaundice in 7 (23.33%) and incidental finding in 7 (23.33%) cases , similar presentation was reported by. [7] The classical triad of abdominal pain, lump and jaundice is not common in a series of CDC by authors like de Vries et al and Lee et al [6,8]. Twenty (80%) of patients had Type- I CDC and 6 (20%) cases had Type- IV cysts. These findings were similar to observations made by deVries JS et al, Jordan PH et al [6,9]. In our series, 28 patients of CDC were picked up on ultrasonography as cystic lesions of the biliary tree. Moreover it could not differentiate CDC from cystic biliary atresia, this limitation of USG was observed by other authors like Chin H M et al [10]. In our study average size of CDC was 3.290 cm ± 0.514cm (range 1.6-10cms). It has been suggested that there is a 97% confidence of choledochal cyst when the diameter of the common bile duct is greater than 1 cm, which was comparable to observations drawn from our series [8] .
Out of 20 cases of cholestasis, 99mTc -HIDA scan was suggestive of BA in 11 cases. In 9 cases HIDA was not suggestive of BA. The sensitivity and specificity of scintigraphy in detecting obstruction range from 83% to 100% and from 33% to 100%, respectively [11]. Moyer et al study observed that scintigraphy had sensitivity and a specificity of 88.24% and 45.71% for diagnosing BA [11]. The accuracy of 99mTc -HIDA scan in our series was comparable to the data reported by Lin et al. [12] and Nadel [13], but higher than that by Gupta et al [14]. It is likely that the discrepant results between our series and across other studies may have arisen due to the variations in radiotracer used, premedication practices, imaging protocol, interpretative criteria, study timing (patient age), and operator experience. MRCP has developed rapidly over past recent past. Its potential application in paediatrics has followed the promising results in adult biliary disorders. We used two dimensional, long acquisition turbo spin sequences. This has been shown to be superior to gradient echo sequence in visualizing the biliary tree [15]. The type and extent of CDC determined by the MRCP correlated (100%) well with the findings IOC in all the 30 patients, this observation was same (100% correlation between the extent of CDC determined by MRCP and IOC) as reported by Kim et al [16]. Abnormal pancreaticobiliay duct union could be delineated by MRCP in 12 cases (40%) out of 30 choledochal cyst patients. Our findings were similar to that reported by authors like Huang S J et al [3], Anupindi S A et al [17] and Kim et al [16].
In our study, the sensitivity, specificity & accuracy of MRCP in delineating anomalous pancreaticobiliary ductal union was 69.23%, 82.35%, &76.66% respectively. In 12 (60%) of the twenty patients in a study by Kim et al [16] APBD-union was clearly visible on MRCP. One reason for this discrepancy could be greater proportion (80%) of type I CDC in our study patients, which decreases the chances of visualization of APBD –union due to the size of the cyst. Mean age of patients in whom ABPD – union was found was higher than patients in whom this APBD –union could be delineated (5.99 ± 2.374 years v/s 3.22 ± 2.776 years). This finding has also been endorsed by authors like Kim et al [16].
Results of previous study undertaken to determine whether MRCP can depict APBD- union associated with choledochal cyst has not been consistent [18]. These differences may be due to different age of patients and imaging techniques. In a study by Clan et al, APBD- union was not delineated in MRCP using 2-0 turbo fast spin-echo sequence with the maximum intensity- projection techniques. However, in paediatric patients, MRCP with half fournier acquisition of a single shot fast spin echo might increase the sensitivity of anomalous pancreaticobiliary duct union detection [19]. APBD -union was mainly seen in Type- I choledochal cyst ,however to see a correlation between type of choledochal cyst and APBD -union was not possible due less number of the cases in our series, which is similar to that reported by Kamisawa et al [20].
Early diagnosis and younger age at time of surgery afford the patients with BA a higher likelihood of a relatively good outcome. Our preliminary data suggested that MRCP in small infants can provide images of the CBD and CHD. Although IOC can provide a direct definitive diagnosis, it is undesirable if alternative techniques are available. Furthermore, many reports have suggested that MRCP is a well established non-invasive modality for visualizing the biliary system, including the first branch of the intrahepatic biliary ducts, extrahepatic bile ducts, and gallbladder [21]. In our study, however, the first branch of the intrahepatic bile ducts was not visible on MRCP images but the main intrahepatic ducts were visible in 11 cases in cholestasis patients. This lack of visibility may have resulted from insufficient bile or the smaller diameter of the biliary duct in neonates and infants being too small. Thus, we used the visibility of the extrahepatic biliary ducts on MRCP images as the diagnostic criterion for non- BA. In contrast, we considered the absence of any portion of the extrahepatic biliary ducts as the diagnostic criterion for BA.
In our study of MRCP in neonatal cholestasis of infancy, 2 false positive cases were reported. A false positive diagnosis of biliary atresia in an infant with sclerosing cholangitis, in whom MRCP could not show extrahepatic bile ducts because of its small calibre, was reported by Guband et al [13]. Although it has been reported that a small gall bladder by MRCP can be considered highly suggestive of biliary atresia, [22] Matos et al states that biliary atresia could be ruled out if the extrahepatic bile duct is completely identified at MRCP [23]. In our study MRCP had a sensitivity, specificity and accuracy of 84.61%, 85.71 and 85% respectively , which was similar sensitivity (85%) to that reported by Yang et al [18] higher than reported by Nortan et al [24].
There are problems of motion induced by respiration, bowel peristalsis, and inadequate sedation which is also a major cause of failed examination. Nonetheless, it is plausible to visualize ducts as small as 1mm in diameter; due to improvement in coil technology, increased speed of acquisition, refinements in respiratory compensation techniques that reduce motion artefacts and newer sequence [25,26]. Paediatric MR cholangio-pancreatography needs to be tailored to different body sizes and ages. The firststep toward such improvement is proper coil selection. Smaller children such as neonates and infants do not need a slab thickness of more than 2 mm. Thin section axial and coronal plane images as well as thick slabs in radiating coronal planes, should be acquired. Because neonates and infants usually have irregular breathing with ranging respiratory amplitude, 3-D FSE imaging with respiratory triggering may not be possible in many of these patients [27]. High cost, limited availability and time required for scanning are problems with MRCP, but it has the capacity to provide anatomic and pathologic details of biliary tract as demonstrated in our series. There are some problems in visualizing non dilated ducts on MRCP, especially for IHD as demonstrated in our study. Lack of signal, long reduced special resolution can make the visualization of ducts more difficult. Since it is difficult to achieve respiratory cycle with a regular rhythm and adequate amplitude in infants and small children.
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