A catheter for use in a medical procedure comprising: a flexible elongate body adapted to be introduced into a patient during said medical procedure and including a strain sensing assembly (100; 140a; 140d) proximate a deformable portion of said elongate body, said strain sensing assembly (100; 140a; 140d) including: a proximal portion (102; 180; 258) and a distal portion (104; 162; 254) separated by at least one standoff member (106; 178; 256) to define a separation between said proximal portion (102; 180; 258) and said distal portion (104, 162; 254); a plurality of transmitting elements extending from said proximal portion (102; 180; 258) and partially spanning said separation, each of said plurality of transmitting elements including a free end to define a plurality of free ends located between said proximal portion (102; 180; 258) and said distal portion (104; 162; 254); and at least one reflecting element (62; 126; 164; 266) operatively coupled with at least one of said plurality of free ends to define a plurality of gaps for interferometery, one of said plurality of gaps being presented between each of said plurality of free ends and said at least one reflecting element (62; 126; 164; 266), each of said plurality of gaps having an operative length between the respective free end and the at least one reflecting element (62; 126; 164; 266), said operative length being variable and responsive to deformation of said deformable portion of said elongate body, wherein said at least one standoff member (106; 178; 256) and said transmitting element include a substantially similar coefficient of thermal expansion in a direction parallel to said operative lengths of said plurality of gaps so that each of said operative lengths remains within a predetermined range when said deformable portion of said elongate body is subject to a predetermined range of bulk temperature change, wherein a difference of said substantially similar coefficients of thermal expansion of said standoff member (106; 178; 256) and said transmitting element is within 2 x 10 -6 /K, and wherein said at least one standoff member (106; 178; 256), said proximal portion (102; 180; 258) and said distal portion (104; 162; 254) are a unibody structure (101; 158; 252). a flexible elongate body adapted to be introduced into a patient during said medical procedure and including a strain sensing assembly (100; 140a; 140d) proximate a deformable portion of said elongate body, said strain sensing assembly (100; 140a; 140d) including: a proximal portion (102; 180; 258) and a distal portion (104; 162; 254) separated by at least one standoff member (106; 178; 256) to define a separation between said proximal portion (102; 180; 258) and said distal portion (104, 162; 254); a plurality of transmitting elements extending from said proximal portion (102; 180; 258) and partially spanning said separation, each of said plurality of transmitting elements including a free end to define a plurality of free ends located between said proximal portion (102; 180; 258) and said distal portion (104; 162; 254); and at least one reflecting element (62; 126; 164; 266) operatively coupled with at least one of said plurality of free ends to define a plurality of gaps for interferometery, one of said plurality of gaps being presented between each of said plurality of free ends and said at least one reflecting element (62; 126; 164; 266), each of said plurality of gaps having an operative length between the respective free end and the at least one reflecting element (62; 126; 164; 266), said operative length being variable and responsive to deformation of said deformable portion of said elongate body, a proximal portion (102; 180; 258) and a distal portion (104; 162; 254) separated by at least one standoff member (106; 178; 256) to define a separation between said proximal portion (102; 180; 258) and said distal portion (104, 162; 254); a plurality of transmitting elements extending from said proximal portion (102; 180; 258) and partially spanning said separation, each of said plurality of transmitting elements including a free end to define a plurality of free ends located between said proximal portion (102; 180; 258) and said distal portion (104; 162; 254); and at least one reflecting element (62; 126; 164; 266) operatively coupled with at least one of said plurality of free ends to define a plurality of gaps for interferometery, one of said plurality of gaps being presented between each of said plurality of free ends and said at least one reflecting element (62; 126; 164; 266), each of said plurality of gaps having an operative length between the respective free end and the at least one reflecting element (62; 126; 164; 266), said operative length being variable and responsive to deformation of said deformable portion of said elongate body, wherein said at least one standoff member (106; 178; 256) and said transmitting element include a substantially similar coefficient of thermal expansion in a direction parallel to said operative lengths of said plurality of gaps so that each of said operative lengths remains within a predetermined range when said deformable portion of said elongate body is subject to a predetermined range of bulk temperature change, wherein a difference of said substantially similar coefficients of thermal expansion of said standoff member (106; 178; 256) and said transmitting element is within 2 x 10 -6 /K, and wherein said at least one standoff member (106; 178; 256), said proximal portion (102; 180; 258) and said distal portion (104; 162; 254) are a unibody structure (101; 158; 252).