logan_ref_region_analysis
====================================================================

.. py:function:: petpal.kinetic_modeling.graphical_analysis.logan_ref_region_analysis(tac_times_in_minutes: numpy.ndarray, input_tac_values: numpy.ndarray, region_tac_values: numpy.ndarray, t_thresh_in_minutes: float, k2_prime: float) -> numpy.ndarray

   Performs Logan with reference region input function on given input TAC, regional TAC, times,
   threshold, and population averaged reference region k2.

   :param tac_times_in_minutes: Array of times in minutes.
   :type tac_times_in_minutes: np.ndarray
   :param input_tac_values: Array of input TAC values
   :type input_tac_values: np.ndarray
   :param region_tac_values: Array of ROI TAC values
   :type region_tac_values: np.ndarray
   :param t_thresh_in_minutes: Threshold time in minutes. Line is fit for all values
                               after the threshold.
   :type t_thresh_in_minutes: np.ndarray
   :param k2_prime: Population averaged k2 value for the reference region.
   :type k2_prime: float

   :returns: *np.ndarray* --

             Array of two elements - (slope, intercept) of the best-fit line to the given
                 data.

   .. important::
       * The interpretation of the values depends on the underlying kinetic model.
       * We assume that the input TAC and ROI TAC values are sampled at the same times.