title: 3 Tesla (23)Na magnetic resonance imaging during aerobic and anaerobic exercise.
abstract: OBJECTIVE
  The aim of the work described here was to determine the feasibility of monitoring Na(+) concentration and distribution in muscle/skin during aerobic/anaerobic exercise with (23)Na magnetic resonance imaging (MRI).
  
  
  METHODS
  The Na(+) concentration and water content of muscle/skin of the left lower leg of six healthy subjects (mean age, 26 years; range, 22-30 years; three men and three women) were assessed before and after aerobic/anaerobic cycle ergometry and during recovery with 3-T (23)Na/(1)H MRI. (23)Na MRI was performed with a custom-made knee coil. A gradient echo sequence with an acquisition time of 3.25 minutes, echo time of 2.07 ms, repetition time of 100 ms, and spatial resolution of 3 × 3 × 30 mm(3) was applied. Phantoms with increasing sodium concentration served for quantification via linear extrapolation. Blood values were determined by blood gas analysis.
  
  
  RESULTS
  The concentration of Na(+) significantly increased during anaerobic exercise in all muscle compartments except the medial gastrocnemius muscle, whereas no significant change was observed in most muscle compartments during aerobic exercise (only the soleus muscle exhibited a significant increase in Na(+) concentration during aerobic exercise: 1.6 ± 1.5 mmol/kg, 4.5%, P = .046). During anaerobic exercise, the mean Na(+) concentration of the triceps surae and the whole leg increased by 9.0% (3.1 ± 2.1 mmol/kg, P = .016) and 6.5% (2.2 ± 1.3 mmol/kg, P < .01). MRI revealed a water-independent increase in Na(+) concentration in most muscle compartments during anaerobic exercise. Na(+) concentration significantly decreased during recovery after anaerobic and aerobic exercise in all muscle compartments except the soleus. The Na(+) concentration of the skin did not significantly change during anaerobic/aerobic exercise.
  
  
  CONCLUSIONS
  Sodium(23) MRI allows reliable and noninvasive visualization and quantification of Na(+) concentration and distribution in muscle and skin during exercise. (23)Na MRI can be used to gain new insights into Na(+) homeostasis, presumably leading to better comprehension of pathophysiology.
authors.affiliation: Department of Radiology, University Hospital Erlangen, Maximiliansplatz 1, Erlangen 91054, Germany. Electronic address: matthias.hammon@uk-erlangen.de.
authors.forename: Matthias
authors.initials: M
authors.lastname: Hammon
authors.affiliation: Department of Radiology, University Hospital Erlangen, Maximiliansplatz 1, Erlangen 91054, Germany.
authors.forename: Susan
authors.initials: S
authors.lastname: Grossmann
authors.affiliation: Department of Nephrology and Hypertension, University Hospital Erlangen, Erlangen, Germany.
authors.forename: Peter
authors.initials: P
authors.lastname: Linz
authors.affiliation: Department of Nephrology and Hypertension, University Hospital Erlangen, Erlangen, Germany.
authors.forename: Christoph
authors.initials: C
authors.lastname: Kopp
authors.affiliation: Department of Nephrology and Hypertension, University Hospital Erlangen, Erlangen, Germany.
authors.forename: Anke
authors.initials: A
authors.lastname: Dahlmann
authors.affiliation: Department of Radiology, University Hospital Erlangen, Maximiliansplatz 1, Erlangen 91054, Germany.
authors.forename: Rolf
authors.initials: R
authors.lastname: Janka
authors.affiliation: Department of Radiology, University Hospital Erlangen, Maximiliansplatz 1, Erlangen 91054, Germany.
authors.forename: Alexander
authors.initials: A
authors.lastname: Cavallaro
authors.affiliation: Department of Radiology, University Hospital Erlangen, Maximiliansplatz 1, Erlangen 91054, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Uder
authors.affiliation: Department of Medicine, Vanderbilt University, Nashville, Tennessee.
authors.forename: Jens
authors.initials: J
authors.lastname: Titze
mesh_terms: D000136:Acid-Base Equilibrium / Q000502:physiology; D000328:Adult; D000693:Anaerobiosis; D001639:Bicarbonates / Q000097:blood; D001834:Body Water / Q000378:metabolism; D001853:Bone Marrow / Q000378:metabolism; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D007719:Knee Joint; D019344:Lactic Acid / Q000097:blood; D007866:Leg; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D018482:Muscle, Skeletal / Q000378:metabolism*; D010101:Oxygen Consumption / Q000502:physiology; D019047:Phantoms, Imaging; D011188:Potassium / Q000097:blood; D012867:Skin / Q000378:metabolism*; D012964:Sodium / Q000097:blood / Q000378:metabolism*; D055815:Young Adult
chemical_list: D001639:Bicarbonates; D019344:Lactic Acid; D012964:Sodium; D011188:Potassium
keywords: 3 Tesla; Magnetic resonance imaging; aerobic; anaerobic; exercise; muscle; skin; sodium