Magnetic resonance spectroscopy (MRS) provides a non-invasive 'window' on biochemical processes within the body. Its use is no longer restricted to the field of research, with applications in clinical practice increasingly common. MRS can be conducted at high magnetic field strengths (typically 11-14 T) on body fluids, cell extracts and tissue samples, with new developments in whole-body magnetic resonance imaging (MRI) allowing clinical MRS at the end of a standard MRI examination, obtaining functional information in addition to anatomical information. We discuss the background physics the busy clinician needs to know before considering using the technique as an investigative tool. Some potential applications of hepatic and cerebral MRS in chronic liver disease are also discussed. ( J CLIN EXP HEPATOL 2015;5:320-328) T he biomedical applications of nuclear magnetic resonance (NMR) are twofold: magnetic resonance imaging (MRI) and magnetic resonance spectroscopy (MRS). The applications of MRS as a research tool are extremely diverse, encompassing studies on isolated cells, body fluids and perfused organs at high magnetic field strengths in an experimental, laboratory-based setting and also in vivo studies using clinical MR systems. 1 In vivo clinical MRS on whole-body MRI scanners has been used to study the metabolism of well-defined regions of the human body, affording a non-invasive 'metabolic window' on a wide range of biochemical processes in the body, including the composition and function of human organs in vivo. 2 Clinical MRS developments have exploited many of the advances in MRI at the magnetic field strengths now used (typically 1.5-3.0 T) and the use of magnetic field gradients. The sensitivity and spatial resolution of MRS is a limiting factor in vivo, but parallel utilisation of in vitro MR spectroscopy of tissue extracts, body fluids and cell lines at much higher magnetic field strengths (typically 11.7-14.1 T) allows more definitive interpretation of the in vivo data. In this article, we aim to equip the clinician with knowledge of the background physics involved in MRS, so that informed decisions can be made for research studies. NUCLEAR MRSNMR refers to the behaviour of atoms subjected to a magnetic field. The phenomenon was first described in 1946 by Bloch and Purcell. Atoms with an odd mass number such as 1 H, 31 P and 13 C possess the quantum property of ''spin'' and behave as dipoles aligning along the axis of an applied magnetic field (Figure 1). During relaxation following excitation, radiofrequency signals are generated which can be expressed as a frequency spectrum. Hydrogen is the most abundant atom in living organisms and using high power magnetic fields on in vitro samples, high resolution metabolic spectra can be obtained with clearly defined metabolite peaks of small molecules (<2 kDa). NUCLEAR SPIN AND ORIENTATIONSNuclear resonance occurs because the nuclei of at least one of the isotopes of most elements possess a magnetic moment. A magnetic moment arises because the nucleus m...

Summarize the typical clinical manifestation of adnexal torsion.List the imaging features of adnexal torsion seen at US, CT, and MRI.Discuss important differential diagnoses based on imaging appearances to avoid potential misinterpretations.

Urinary NMR changes in Bangladeshi HCC were identified, corroborating previous findings from Egypt and West Africa. These findings could form the basis for the development of a cost-effective HCC dipstick screening test.

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