| CPC A61B 5/0082 (2013.01) [A61B 5/0261 (2013.01); A61B 5/41 (2013.01); A61B 5/6826 (2013.01); A61B 5/6831 (2013.01); A61B 5/6843 (2013.01); A61B 5/7235 (2013.01); A61B 2562/0238 (2013.01); A61B 2562/043 (2013.01)] | 15 Claims |

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15. A method of diagnosing systemic lupus erythematosus (SLE) in a subject, the method comprising:
(a) providing an imaging system comprising:
a flexible substrate;
a plurality of light emitting diodes (LEDs) positioned on the flexible substrate at intervals along the flexible substrate, wherein the LEDs are positioned with respect to the flexible substrate to couple light into a finger of a subject;
a plurality of photodetectors positioned on the flexible substrate at intervals along the flexible substrate, wherein the LEDs are positioned with respect to the flexible substrate to detect light emanating from the finger;
a controller; and
a plurality of LED drivers configured to selectively illuminate each of the LEDs in response to receipt of a command from the controller,
wherein the controller accepts an output from each of the photodetectors, and determines, from each output from each of the photodetectors, a level of light absorption or transmission within the finger;
(b) affixing the plurality of LEDs and the plurality of photodetectors against the subject's body near a joint;
(c) sequentially transmitting light from each of the plurality of LEDs into the subject's body; and
(d) acquiring signals from each of the plurality of photodetectors, wherein the signals represent an amount of light that reaches each of the plurality of photodetectors during a time when each of the plurality of LEDs is transmitting light into the subject's body;
(e) determining a rise time of the acquired signals that occurs in response to an increase of blood volume that results from an inflation of a pressure cuff, wherein the inflation of the pressure cuff occurs between a start time and a stop time, wherein the rise time is determined by measuring the time it takes for the acquired signals to rise to 90% of a largest value starting from 10% of the largest value;
(f) determining a plateau time of the acquired signals that occurs in response to the increase of blood volume and a subsequent decrease of blood volume that results from the inflation and subsequent deflation of the pressure cuff, wherein the plateau time is determined by measuring a time interval between points of 90% of a maximum from both a rising edge and a falling edge of the acquired signals; and
(e) outputting an indication that the joint is likely affected by SLE when the determined rise time is short and the determined plateau time is long.
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