(SR) Particular type of partial saturation pulse sequence in which the preceding pulses leave the spins in a state of saturation, so that recovery at the time of the next pulse has taken place from an initial condition of no magnetization. A rare used MRI pulse sequence that generates a predominantly proton density dependent signal, basically employing a 90° RF excitation pulse, with a very long repetition time. With this technique T1 times can be measured faster than with inversion recovery pulse sequences.
This saturation recovery sequence consists of multiple 90° radio frequency (RF) pulses with a short repetition time. A spoiler gradient pulse dephases the longitudinal magnetization that remains after the first 90° radio frequency pulse. A repetition time interval after the application of this spoiling gradient turns an additional 90° pulse the new developed longitudinal magnetization into the transverse plane, followed by recording a gradient echo.

The sensitive point in an object (or a region) is the point from which information is being measured, as in sequential point imaging or in single voxel MR spectroscopy sequential point imaging used. To define a sensitive point, it must be selected in three dimensions. Different combinations of selective excitation, inversion, or saturation pulses can be used. Sometimes, combinations of two or more measurements are necessary to define the sensitive point (or volume).

See also Magnetic Resonance Spectroscopy.

The elimination or reduction of a particular signal by, for example, the application of a narrow band frequency-selective preparation pulse centered at the resonant frequency of the signal. This can also be accomplished using an inversion recovery technique to null the signal as it recovers its longitudinal magnetization.

(SEMS) This pulse sequence is composed of a 90° RF pulse followed by a 180° refocusing pulse. Both RF pulses are applied in the presence of a slice select gradient.
By choosing of different TR and TE, depending on the T1 and T2 values of the tissues, proton density, T1 weighted and T2 weighted images can be acquired.
The inversion recovery option enlarge the RF pulses with a 180° inverting pulse, applied a TI time before the beginning of the pulse sequence in order to manipulate image contrast.
See also Spin Echo Sequence.

Magnetic resonance imaging (MRI) of the spine is a noninvasive procedure to evaluate different types of tissue, including the spinal cord, vertebral disks and spaces between the vertebrae through which the nerves travel, as well as distinguish healthy tissue from diseased tissue.
The cervical, thoracic and lumbar spine MRI should be scanned in individual sections. The scan protocol parameter like e.g. the field of view (FOV), slice thickness and matrix are usually different for cervical, thoracic and lumbar spine MRI, but the method is similar. The standard views in the basic spinal MRI scan to create detailed slices (cross sections) are sagittal T1 weighted and T2 weighted images over the whole body part, and transverse (e.g. multi angle oblique) over the region of interest with different pulse sequences according to the result of the sagittal slices. Additional views or different types of pulse sequences like fat suppression, fluid attenuation inversion recovery (FLAIR) or diffusion weighted imaging are created dependent on the indication.

Indications:

Contrast enhanced MRI techniques delineate infections vs. malignancies, show a syrinx cavity and support to differentiate the postoperative conditions. After surgery for disk disease, significant fibrosis can occur in the spine. This scarring can mimic residual disk herniation. Magnetic resonance myelography evaluates spinal stenosis and various intervertebral discs can be imaged with multi angle oblique techniques. Cine series can be used to show true range of motion studies of parts of the spine. Advanced open MRI devices are developed to perform positional scans in the position of pain or symptom (e.g. Uprightâ„¢ MRI formerly Stand-Up MRI).