MRCP contributes to evaluate the biliopancreatic system,
acute or chronic pancreatitis and cystic tumors of the pancreas at many institutions [1] (Fig.1).
The 3D-FSE sequence can produce high spatial resolution of MRCP images.
Thin slice thickness with gapless enables to demonstrate precise images such as small stones of the biliary system,
secondary branching of the main pancreatic duct and IHBD [2] (Fig.1).
An alternative method of producing 3D-MRCP images is to use FSE sequence with a 90° flip-back pulse that is called FRFSE.
This sequence is unique because the residual transverse magnetization is refocused along the z-axis by a -90° fast recovery pulse after long echo train length (ETL).
This technique accelerates relaxation of the longitudinal magnetization and leads a reduction in TR without a loss of SNR and obtains long T2-weighted tissue image like fluid [2,3].
Variable RFA techniques can maintain higher signal intensity in long ETL,
produce higher SNR and acquire high quality volumetric image due to centric view ordering [4].
Cube is a single-slab 3D-FSE imaging sequence with modulated RFA that generates T2-weighted soft tissue images to reduce blur and specific absorption rate (SAR) under very long ETL applied [5,6] (Fig.2).
In the previous report,
SAR was reduced at about 70% using variable RFA at 3T [7].
Compared conventional constant flip angle (FA) 3D-MRCP with variable RFA 3D-MRCP images on a 3.0 T MR scanner,
the previous study revealed that the latter sequence provided significantly better image of IHBD [8].
The variable RFA technique on a 1.5 T MR scanner also presented better image of the biliopancreatic system [9].
3D-T2 weighed imaging (T2WI) on Cube sequence has been adapted to various application of knee [10-12],
ankle [13],
uterus [14],
rectum [15],
lacrimal gland [16] and MRCP [17] (Fig.2).
But technique of Heavily T2WI such as MRCP had been reported less than musculoskeletal MRI.
Cube enhance is ready for four modes including “Normal”,
“MSK-PD”,
“Spine T2”,
and “Brain T1” to accomplish 3D-Cube sequence,
however,
“Normal” or “Spine T2” has been commonly chosen to T2WI contrast.
The maximum TE was set shorter with this “Normal” or “Spine T2”,
so that Heavily T2WI was not obtained nor variable RFA.
On the other hand,
“MSK-PD” made possible to select variable RFA that was able to extend the maximum TE.
Therefore 3D-Cube MRCP is expected to improve the detectability of T2 long region.