generally , an apparatus including an optical probe capable of taking an oct image is inserted into interstitial tissue . the optical probe is manually moved ( e . g ., by a technician or a robot ). when the optical probe is moved more than approximately 5 microns from a reference point ( e . g ., a guidance needle or a handle ), an oct reflectivity profile or a - line is taken . each oct a - line is analyzed by a data processor to determine whether or not it is a repeat of the previous a - line . repeated a - lines are discarded . the data process presents an aggregate oct image of the interstitial tissue based on each non - discarded oct a - line . fig1 is a diagram of a hand - held optical imaging device 100 , according to an illustrative embodiment of the invention . the hand - held optical imaging device 100 includes an optical fiber 105 , an optical scale 110 , a position sensor 115 ( e . g ., optical encoder ), a connector 120 ( e . g ., male luerlock connector ), a guidance needle 125 , and an optical probe 130 encapsulated into a hypodermic tube with a sharp tip . when in use , the hand - held oct imaging device 100 emits a light beam 140 . the connector 120 is coupled to the guidance needle 125 . the guidance needle 125 has the optical probe 130 disposed therein . the optical probe 130 passes through the connector 120 and has attached or engraved an optical scale 110 . the optical encoder 115 is coupled to the connector 120 at a location that allows the optical encoder 115 to detect a change in position of the optical scale 110 . the optical fiber 105 is coupled to the optical probe and connects it to an optical imaging instrument ( not shown ). in some embodiments , the optical probe 130 is a single mode ( sm ) oct fiber probe that is terminated with a side looking micro - objective lens . in various embodiments , the optical probe 130 is a combined oct / fluorescence or absorption / raman spectroscopy probe , which utilizes either a double clad fiber to collect the fluorescence or absorption / raman spectroscopy signal , or a separate fiber adjacent to the oct fiber . in some embodiments , the guidance needle 125 is a transcutaneous biopsy needle . in some embodiments , the guidance needle 125 is up to several inches in length ( e . g ., 3 to 15 inches ). in some embodiments , the guidance needle 125 is a long biopsy needle ( e . g ., 4 to 6 feet in length ), used in conjunction with gi endoscopes , being delivered inside the body through the instrument channel of such endoscopes . during operation , the guidance needle 125 is first inserted into the interstitial sample ( e . g ., kidney , heart , lungs , liver , etc ., of a patient ) by an operator . ultrasound or ct guidance can be used for correct placement of the transcutaneous biopsy needles within the tissue location to be examined , while endoscopy guidance is used for proper placement of long needles . the operator inserts the optical probe 130 through the guidance needle 125 until the tip of the optical probe 130 outreaches the tip of the guidance needle 130 to a position sufficient to send the imaging beam to the interstitial tissue ( e . g ., 2 - 5 mm ). once in a desired position , the operator can maneuver only the optical probe 130 to extend further into the interstitial tissue , while the guidance needle 125 remains substantially unmoved . the optical encoder 115 detects any incremental movement of the optical scale 110 . when the optical encoder 115 detects that the location of the optical probe 130 moves more than a predetermined threshold ( e . g ., 5 microns or more ), the optical encoder 115 generates a trigger signal that is transmitted to an oct spectrometer camera ( not shown ). in some embodiments , the predetermined threshold is a function of the resolution of the encoder / scale assembly . the trigger signal instructs the oct spectrometer camera to take a signal ( e . g ., record an oct reflectivity profile or a - line ). an operator maneuvering the optical probe 130 can move as quickly or as slowly as is needed ( e . g ., for comfort of the patient ) because the triggering event for taking an oct image can be based on location and not time . for each oct a - line taken , the data processor compares the image with a previous oct a - line taken . if the a - lines are substantially the same , then the data processor discards the repeated a - lines . an aggregate oct image ( e . g ., a tomographic oct image or cross - sectional ) is compiled based on all non - repeat a - lines . in this manner , if the optical probe 130 is stuck within the interstitial tissue such that the interstitial tissue moves with the optical probe 130 , a correction is made to discard the repeat voxels from the image . the aggregate oct image can be displayed in real - time . in some embodiments , the predetermined threshold is based on desired imaging resolution , usually 5 to 25 microns . in some embodiments , the optical scale 110 is an engraved optical scale . in some other embodiments , the optical scale 110 is an attached scale . an attached scale can allow the optical probe to be disposable with a low cost . in some embodiments , the optical probe 130 is between 300 and 2000 microns in diameter . in some embodiments , the optical probe 130 diameter depends on the size and the length of the biopsy guidance needle . in some embodiments , the optical probe 130 is a regular single mode ( sm ) fiber that is optic - based . in some embodiments , the optical probe 130 is a combination of a sm fiber and a multimode ( mm ) fiber , the sm being used for oct imaging and the mm used for fluorescence or spectroscope . in some embodiments , the optical probe 130 is a dual clad fiber where the core is used for oct and spectroscopy or fluorescence illumination , and the 2 nd clad for collecting the fluorescence or spectroscopy photons . fig2 is a diagram of a hand - held oct imaging device 200 , according to an illustrative embodiment of the invention . the hand - held oct imaging device 200 includes an optical probe 210 , a biopsy needle 220 , a jacket 230 , an optical scale 240 , an encoder 250 , a holder 260 and a handle 270 . the optical probe 210 is positioned within the biopsy needle 220 . the biopsy needle is positioned within a jacket 230 . the jacket 230 is coupled to the holder 260 . the holder 260 is coupled to the optical scale 240 . the holder 260 is coupled to the handle 270 . the handle 270 is coupled to the encoder 250 . during operation , the biopsy needle 220 with a stilet disposed therein ( not shown ) is placed within the interstitial tissue of interest under endoscopic guidance . the stilet is removed and the optical probe 210 is inserted into the biopsy needle 220 until it reaches the interstitial tissue ( e . g ., a pancreas , stomach , or other organ of interest ). the optical probe 210 is locked to the biopsy needle 220 , so that the optical probe 210 and the biopsy needle 220 can move together when the handle 270 is moved . the biopsy needle 220 is maneuvered by a person ( or a robot ) manipulating the handle 270 . when the handle 270 is moved forward , the biopsy needle 220 and the optical probe 210 are moved forward . the encoder 250 attached to the handle 270 moves relative to the optical scale 240 , which is attached to the holder 260 . therefore , any movement of the optical probe 210 inside the tissue is monitored by the encoder 250 , which generates trigger pulses and starts the acquisition of the oct a - lines . fig3 is a flow chart of a method 300 for sample oct imaging and biopsy guidance , according to an illustrative embodiment of the invention . the method involves inserting a guidance needle ( e . g ., guidance needle 125 as shown above in fig1 ) and an optical probe ( e . g . interstitial sample ( step 310 ), the optical probe being positioned within the guidance needle . in some embodiments , the guidance needle is inserted into the sample with a stilet , the stilet is removed and then the optical probe is inserted . in some embodiments , the guidance needle and the optical probe are coupled prior to insertion . the sample can be any tissue of a mammal that needs to be investigated or any biological / non - biological specimen . the investigation site , in a mammal , can be a site of interest having some shape and size defined by previous radiological or ultrasound imaging , or by real - time radiological or ultrasound imaging . for example , for a patient that previously had cancer ( e . g ., breast cancer ), the investigation site can be well defined area having a different radiological appearance than the surrounding tissue . in some embodiments , the investigation site is based on the images ( e . g ., ct or ultrasound ) taken during the investigation ( e . g ., biopsy procedure ). the optical probe can be an oct imaging probe . the method also involves establishing , using a position sensor , a reference location of the optical probe at a first spatial position at the investigation site relative to the guidance needle ( step 320 ). the method also involves capturing a first optical coherence tomography ( oct ) a - line with the optical probe at the first spatial position when the optical probe is moved relative to the reference location ( step 330 ). the method also involves detecting , using the position sensor , a spatial location of the optical probe relative to the reference location during movement of the optical probe within the sample ( step 340 ). the position sensor can be an optical encoder , a magnetic position sensor , or any position sensor as is known in the art . the method also involves capturing an oct a - line with the optical probe at a second spatial position if the reference location and the spatial location are separated by greater than a predetermined threshold value ( step 350 ). in some embodiments , the predefined threshold value is 5 microns . in various embodiments , the predefined threshold value is between 1 and 25 microns . the method also involves determining whether the second oct a - line is identical to the first oct a - line ( step 360 ). in some embodiments , the determination as to whether the first and second oct a - lines are the same is based on the following : if i axi + 1 − i axi & gt ; k , then a xi + 1 = 0 ( eqn . 1 ) where i ax is intensity of each pixel from successive a line of the first oct image , i axi + 1 is intensity of each pixel from successive a line of the second oct image , and k is a threshold constant . in various embodiments , k is an experimentally established threshold based on image intensity , or is automatically determined by the oct processor . if the first oct a - line and the second oct a - line are identical then the second oct a - line is discarded ( step 370 ). if the first oct a - line and the second oct a - line are not identical the first oct a - line and the second oct a - line are stored ( step 380 ). the first oct a - line and the second oct a - line can be stored in an array . in this manner , at periodic intervals , an oct a - line image is taken each time the optical probe moves beyond the predetermined threshold . for each a - line image that is taken , if it is not identical to the previous a - line image , then it is stored in the array . the array can be used by the processor to append all of the non - discarded a - lines into one cohesive oct image . in some embodiments , the imaging probe is a combined oct / fluorescence or oct / spectroscopy image . the fluorescence or spectroscopy data can be used in conjunction with the oct data to provide enhanced differentiation of tissue nature ( e . g ., normal , solid tumor , heterogeneous tissue , necrotic tissue ). either the operator or an automated tissue differentiation algorithm can be used to determine tissue nature in real time . in some embodiments , the probe is reoriented into a different spatial location of the tissue , e . g ., if the investigated location by oct or combined oct / fluorescence / spectroscopy does not show a correlation with the radiological finding . in these embodiments , the optical probe can be manually retracted until it reaches the tip of the biopsy guidance needle and the needle optical probe assembly can be reoriented to a different position or angle to reach a different area of the investigated tissue ( 350 ) to collect a new data set . if used for biopsy guidance , the procedure can be repeated several times until the operator determines , based on the collected data , that a specific location within the tissue specimen is the right one to collect a tissue specimen . then , the optical probe is retracted and the biopsy cutting needle is inserted through the guidance needle to collect a tissue specimen ( biopsy core or an assembly of cells and fluid ( for aspiration biopsies ). fig4 is a schematic of a system 400 for oct imaging includes a hand - held oct imaging device , according to an illustrative embodiment of the invention . the system 400 includes a spectroscopy / fluorescence imaging unit 410 , an oct unit 420 , a system control and data processing unit 430 , a signal conditioner 440 , an oct imaging probe 450 that includes a position sensor 455 and a division multiplexing fiber component 460 . the spectroscopy / fluorescent imaging unit 410 and the oct unit 420 are in communication with the oct imaging probe 450 through the division multiplexing fiber component 460 . the spectroscopy / fluorescent imaging unit 410 and the oct unit 420 are also in communication with the system control and data processing unit 430 . the system control and data processing unit 430 is also in communication with the oct imaging probe 450 via the signal conditioning unit 440 . during operation , the oct imaging probe 450 is inserted into interstitial tissue . the position sensor 455 detects the position of the probe in the interstitial tissue during imaging . the signal conditioning unit 440 receives the imaging data and minimizes noise on the received data and / or instructs the system control and data processing unit 430 to start acquisition of the signals . the system control and data processing unit uses the position data from the position sensor 455 to append the consecutive signals to an array and form a cross - sectional oct image . it also determines whether consecutive a - lines are repeats or new a - lines of an investigation site of the interstitial tissue ( e . g ., for example , by using method 300 ). the spectroscopy / fluorescence imaging unit 410 transmits / receives signals from the imaging probe that can be used in correlation with the oct image to improve tissue discrimination . the wavelength can be between 400 and 800 nanometers . fig5 is a graph 500 showing a comparison of oct images of interstitial tissue with and without correction , according to an illustrative embodiment of the invention . the image with encoder feedback represents a distorted image of the tissue true morphology , while the one with encoder feedback represents the true morphology of the tissue . fig6 is a graph 600 showing a comparison of oct images of interstitial tissue , according to an illustrative embodiment of the invention . as observed the repeated voxels from the uncorrected image are eliminated from the corrected image , which is physically shorter and represents the true morphology of the tissue although various aspects of the disclosed methods , devices and systems have been shown and described , modifications may occur to those skilled in the art upon reading the specification . the present application includes such modifications and is limited only by the scope of the claims .
a handheld optical coherence tomography imaging and tissue sampling system and method of imaging and sampling a tissue is disclosed . the method includes inserting a catheter probe into a biopsy needle . the biopsy needle can be attached to a hand - held scanning and sampling device . the biopsy needle is maneuvered to an investigation site . a three - dimensional image of the tissue at the investigation site is captured with the catheter probe .