Direct visualization of pancreatic juice flow using unenhanced MRI with spin labeling can be aid in diagnosing chronic pancreatitis. AJR Am J Roentgenol. 2014;202:1027-1034. [PMID: 24758655 DOI: 10.2214/ajr.13.10886]

Comparison of Slab and Pencil Beam Labeling in Spin-labeled MR Imaging for Pancreatic Juice Flow Visualization

The usefulness of a highly targeted pencil beam (PB) label was compared with the commonly used slab label for direct visualization of pancreaticobiliary reflux using the time-spatial labeling inversion pulse (time-SLIP) technique. Signal profiles of flow phantom images obtained with a 1.5T MRI were analyzed. Both labels had similar labeling capabilities, but the edge characteristics of the PB label were blunt. Next, sixty-eight patients were classified into two groups according to the angle of the pancreaticobiliary ducts, and the displacement of the pancreatic ducts in respiratory fluctuation was measured. The results were approximately 7 mm in both groups. The blunt edge characteristics of the PB label suggest that it is robust to respiratory fluctuations. The overall labeling ability of the PB is comparable to that of the slab. In the larger angle of pancreaticobiliary ducts, the PB label may be able to label the pancreatic duct more selectively.

Using Spin-labeled MR Imaging to Depict Slow Pancreatic Juice Flow

This study evaluated the dependence of the signal characteristics of time-spatial labeling inversion pulse (time-SLIP) on flow velocity and tag thickness to depict the pancreatic juice flow by analyzing signal profile using a tube phantom study. The tag edge property was evaluated by edge rise distance (ERD). For various slow flow velocities and tag thicknesses, the signal profile characteristics were evaluated using two indices: the tag center value (RTCV) reduction rate and the total signal value along the tube (TSVT). ERD, which was about 10% of the tag thickness, was higher for thicker tags, making slow flow detection difficult. TSVT was proportional to the thickness of the tag and was preserved irrespective of the flow velocity. RTCV became lower with higher flow velocity and decreased significantly with thinner tags. These results suggest that the visualization of pancreatic juice flow might improve stability by considering the appropriate tag thickness.

Is Cambridge scoring in chronic pancreatitis the same using ERCP and MRCP?: A need for revision of standards

PURPOSE

Grading of chronic pancreatitis (CP) is a clinical and radiologic challenge. Retrograde cholangiopancreatography (ERCP) and magnetic resonance cholangiopancreatography (MRCP) use a version of the Cambridge criteria for ductal evaluation and CP staging, but interchangeability between the modalities lacks validation. This work compares ERCP and MRCP Cambridge scores and evaluates diagnostic performance of MRCP in a large cohort of patients with CP.

METHODS

A large radiology database was searched for CP patients who underwent MRCP between 2003 and 2013. Next, patients who also had an ERCP within 90 days of their MRCP were selected. These were categorized into mild, moderate, and severe CP using the standardized Cambridge classification for ERCP. Radiologists blinded to ERCP findings then rated MRCP with modified Cambridge scores.

RESULTS

The cohort comprised 325 patients (mean age 51 years; 56% female). By ERCP Cambridge classification, 122 had mild CP, 109 moderate CP, and 94 severe CP. MRCP and ERCP showed total agreement of Cambridge score in only 43% of cases. With ERCP as reference, the sensitivity and specificity of MRCP in detecting Cambridge scores 4 + 5 (main-duct predominant) were 75.9% and 64.3%, and for Cambridge score 3 (side-branch predominant) it was 60.0% and 76.9%, respectively.

CONCLUSIONS

There is a lack of strong concordance between ERCP- and MRCP-based grading of CP using the Cambridge criteria. MRCP had moderate to good performance in diagnosing side-branch predominant versus main-duct predominant CP. This suggests an inherent challenge in comparing literature and calls for a revision of the standards.

[Application of a modified Time-SLIP MRI sequence for visualization of cerebrospinal fluid movement in the cerebral aqueduct and cervical spinal canal]

Direct visualization of rapid cerebrospinal fluid movements is a topical task of neurosurgery, which has applications such as evaluating hydrocephalus and the effectiveness of 3rd ventriculostomy.

PURPOSE

The study purpose was to evaluate the capabilities of a modified Time-SLIP pulse MRI sequence for visualization of fluid (CSF) movements in the phantom, healthy subject, and patient.

MATERIAL AND METHODS

The study was performed in a phantom simulating pulsed CSF movements, healthy volunteers (9 people), and patients without impaired CSF dynamics (12 people), whose data were used to determine mean CSF flow parameters, as well as in 1 patient after 3rd ventriculostomy. A 1.5 T MRI instrument was used. The Time-SLIP parameters were as follows: TR = 8,500 ms; TEeff = 80 ms; Thk = 5.0 mm; tag spacing = 30 mm; NEX 7; inversion time (BBTI) = 2,000/3,000 ms; no cardiosynchronization. Scanning time was 2:16 min. The estimated parameter was the length of motion (LOM) of CSF.

RESULTS

According to a study on a phantom simulating various conditions of oscillatory fluid motion, the mean LOM determination error in the modified Time-SLIP mode was 20%. This technique provided the following LOM data for the cerebral aqueduct (median, 25-75% quartiles): 13.0 (9.5-16.0) mm for BBTI of 2,000ms and 30.2 (23.7-35.3) mm for BBTI of 3,000 ms, i.e. 2.3-fold higher. This difference may be explained by an intense turbulent current leading to rapid CSF exchange between the 3rd and 4th ventricles and prolonged CSF movement during several heart contractions. Quantitative parameters of CSF movement at the C1-C2 level were determined. Additionally, Time-SLIP was used to evaluate performance of a third ventricle fistula.

CONCLUSION

We have proposed a modified Time-SLIP pulse sequence that does not require cardiosynchronization. The mean relative error in determining the CSF movement distance was 20%. The mean quantitative parameters of CSF movement in the cerebral aqueduct and at the C1-C2 level were obtained. Turbulent CSF flow is found in the cerebral aqueduct, which leads to rapid exchange between the 3rd and 4th ventricles.

Guidelines for the Diagnostic Cross Sectional Imaging and Severity Scoring of Chronic Pancreatitis

The paper presents the international guidelines for imaging evaluation of chronic pancreatitis. The following consensus was obtained: Computed tomography (CT) is often the most appropriate initial imaging modality for evaluation of patients with suspected chronic pancreatitis (CP) depicting most changes in pancreatic morphology. CT is also indicated to exclude other potential intraabdominal pathologies presenting with symptoms similar to CP. However, CT cannot exclude a diagnosis of CP nor can it be used to exclusively diagnose early or mild disease. Here magnetic resonance imaging (MRI) and MR cholangiopancreatography (MRCP) is superior and is indicated especially in patients where no specific pathological changes are seen on CT. Secretin-stimulated MRCP is more accurate than standard MRCP in the depiction of subtle ductal changes. It should be performed after a negative MRCP, when there is still clinical suspicion of CP. Endoscopic ultrasound (EUS) can also be used to diagnose parenchymal and ductal changes mainly during the early stage of the disease. No validated radiological severity scoring systems for CP are available, although a modified Cambridge Classification has been used for MRCP. There is an unmet need for development of a new and validated radiological CP severity scoring system based on imaging criteria including glandular volume loss, ductal changes, parenchymal calcifications and parenchymal fibrosis based on CT and/or MRI. Secretin-stimulated MRCP in addition, can provide assessment of exocrine function and ductal compliance. An algorithm is presented, where these imaging parameters can be incorporated together with clinical findings in the classification and severity grading of CP.

Chronic pancreatitis

Chronic pancreatitis is defined as a pathological fibro-inflammatory syndrome of the pancreas in individuals with genetic, environmental and/or other risk factors who develop persistent pathological responses to parenchymal injury or stress. Potential causes can include toxic factors (such as alcohol or smoking), metabolic abnormalities, idiopathic mechanisms, genetics, autoimmune responses and obstructive mechanisms. The pathophysiology of chronic pancreatitis is fairly complex and includes acinar cell injury, acinar stress responses, duct dysfunction, persistent or altered inflammation, and/or neuro-immune crosstalk, but these mechanisms are not completely understood. Chronic pancreatitis is characterized by ongoing inflammation of the pancreas that results in progressive loss of the endocrine and exocrine compartment owing to atrophy and/or replacement with fibrotic tissue. Functional consequences include recurrent or constant abdominal pain, diabetes mellitus (endocrine insufficiency) and maldigestion (exocrine insufficiency). Diagnosing early-stage chronic pancreatitis is challenging as changes are subtle, ill-defined and overlap those of other disorders. Later stages are characterized by variable fibrosis and calcification of the pancreatic parenchyma; dilatation, distortion and stricturing of the pancreatic ducts; pseudocysts; intrapancreatic bile duct stricturing; narrowing of the duodenum; and superior mesenteric, portal and/or splenic vein thrombosis. Treatment options comprise medical, radiological, endoscopic and surgical interventions, but evidence-based approaches are limited. This Primer highlights the major progress that has been made in understanding the pathophysiology, presentation, prevalence and management of chronic pancreatitis and its complications.

Pancreaticobiliary reflux as a high-risk factor for biliary malignancy: Clinical features and diagnostic advancements

Pancreaticobiliary junction is composed of complex structure with which biliary duct and pancreatic duct assemble and go out into the ampulla of Vater during duodenum wall surrounding the sphincter of Oddi. Although the sphincter of Oddi functionally prevents the reflux of pancreatic juice, pancreaticobiliary reflux (PBR) occurs when function of the sphincter of Oddi halt. The anatomically abnormal junction is termed pancreaticobiliary maljunction (PBM) and is characterized by pancreatic and bile ducts joining outside of the duodenal wall. PBM is an important anatomical finding because many studies have revealed that biliary malignancies are related due to the carcinogenetic effect of the pancreatic back flow on the biliary mucosa. On the other hand, several studies have been published on the reflux of pancreatic juice into the bile duct without morphological PBM, and the correlation of such cases with biliary diseases, especially biliary malignancies, is drawing considerable attention. Although it has long been possible to diagnose PBM by various imaging modalities, PBR without PBM has remained difficult to assess. Therefore, the pathological features of PBR without PBM have not been yet fully elucidated. Lately, a new method of diagnosing PBR without PBM has appeared, and the features of PBR without PBM should soon be better understood.

Chronic pancreatitis

PURPOSE OF REVIEW

We review selected important clinical observations in chronic pancreatitis reported in 2013.

RECENT FINDINGS

Early diagnosis of chronic pancreatitis remains difficult, although newer techniques utilizing endoscopic ultrasonography-elastography and MRI hold promise. Patients with chronic pancreatitis are at risk of nutritional deficiencies. Osteoporosis, osteopenia, and bone fracture are particularly common in these patients, and require active intervention and treatment. Diabetes caused by chronic pancreatitis, type 3c diabetes, has specific characteristics and requires careful management. Antioxidants and neuromodulators may decrease pain in some patients with chronic pancreatitis. Endoscopic treatment is effective and can be utilized in patients with painful chronic pancreatitis, although randomized trials demonstrate that surgical therapy is somewhat more durable and effective. Although surgery has typically been a last resort, some advocate early surgical intervention but the optimal time remains unknown.

SUMMARY

Early diagnosis of pancreatitis may be improved by newer techniques associated with endoscopic ultrasonography imaging. Treatment of nutritional deficiencies and diabetes is an important aspect of treating chronic pancreatitis. Pain relief with adjunct means of pain modulation should be tried before starting narcotics for pain control. Endoscopic therapy is appropriate for treating chronic pancreatitis and its local complications and surgical intervention can be considered early in carefully selected individuals.