diff --git a/dap/algos/spiana.py b/dap/algos/spiana.py
index 593aaf7..5a8e935 100644
--- a/dap/algos/spiana.py
+++ b/dap/algos/spiana.py
@@ -11,17 +11,10 @@ def calc_spi_analysis(results):
     spi_limit = results["spi_limit"]
     roi_intensities_normalised = results["roi_intensities_normalised"]
 
-    if len(spi_limit) != 2:
-        return
-
-    if len(roi_intensities_normalised) < 2:
-        return
-
     number_of_spots = 0
-    if roi_intensities_normalised[0] >= spi_limit[0]:
-        number_of_spots += 25
-    if roi_intensities_normalised[1] >= spi_limit[1]:
-        number_of_spots += 50
+    for index, (rin, sl) in enumerate(zip(roi_intensities_normalised, spi_limit)):
+        if rin >= sl:
+            number_of_spots += 25 * (index+1)
 
     results["number_of_spots"] = number_of_spots