From b59187c74dfd91fc886ef0314809b097c5f84006 Mon Sep 17 00:00:00 2001
From: Davide Punzo <punzodavide@hotmail.it>
Date: Thu, 3 Dec 2020 17:08:38 +0100
Subject: [PATCH] Re #2113: disable 2D MPR when datasets have  multiple slices
 for the same ImagePositionPatient (#2160)

fix: disable 2D MPR when datasets are 4D
---
 .../toolbarComponents/VTKMPRToolbarButton.js  | 52 ++++++++++++++++++-
 1 file changed, 51 insertions(+), 1 deletion(-)

diff --git a/extensions/vtk/src/toolbarComponents/VTKMPRToolbarButton.js b/extensions/vtk/src/toolbarComponents/VTKMPRToolbarButton.js
index 82ebbc5e6..7f90fcd71 100644
--- a/extensions/vtk/src/toolbarComponents/VTKMPRToolbarButton.js
+++ b/extensions/vtk/src/toolbarComponents/VTKMPRToolbarButton.js
@@ -31,7 +31,57 @@ const _isDisplaySetReconstructable = (viewportSpecificData = {}, activeViewportI
 
   if (!displaySet) {
     return false;
-  };
+  }
+
+  // 2D MPR is not currently available for 4D datasets.
+
+  // Assuming that slices at different time have the same position, here we just check if
+  // there are multiple slices for the same ImagePositionPatient and disable MPR.
+
+  // A better heuristic would be checking 4D tags, e.g. the presence of multiple TemporalPositionIdentifier values.
+  // However, some studies (e.g. https://github.com/OHIF/Viewers/issues/2113) do not have such tags.
+
+  for (let ii = 0; ii < displaySet.numImageFrames; ++ii){
+    const imageIdControl = displaySet.images[ii].getImageId()
+    const instanceMetadataControl = cornerstone.metaData.get('instance', imageIdControl)
+
+    if (!instanceMetadataControl ||
+      instanceMetadataControl === undefined ||
+      !instanceMetadataControl.ImagePositionPatient ||
+      instanceMetadataControl.ImagePositionPatient === undefined ) {
+      // if ImagePositionPatient is missing, skip the 4D datasets check.
+      // do not return false, because it could be a 3D dataset.
+      continue;
+    }
+
+    let xImagePositionPatientControl = instanceMetadataControl.ImagePositionPatient[0];
+    let yImagePositionPatientControl = instanceMetadataControl.ImagePositionPatient[1];
+    let zImagePositionPatientControl = instanceMetadataControl.ImagePositionPatient[2];
+
+    for (let jj = ii + 1; jj < displaySet.numImageFrames; ++jj){
+      const imageId = displaySet.images[jj].getImageId()
+      const instanceMetadata = cornerstone.metaData.get('instance', imageId)
+
+      if (!instanceMetadata ||
+        instanceMetadata === undefined ||
+        !instanceMetadata.ImagePositionPatient ||
+        instanceMetadata.ImagePositionPatient === undefined) {
+        // if ImagePositionPatient is missing, skip the 4D datasets check.
+        // do not return false, because it could be a 3D dataset.
+        continue;
+      }
+
+      let xImagePositionPatient = instanceMetadata.ImagePositionPatient[0];
+      let yImagePositionPatient = instanceMetadata.ImagePositionPatient[1];
+      let zImagePositionPatient = instanceMetadata.ImagePositionPatient[2];
+
+      if (xImagePositionPatientControl === xImagePositionPatient &&
+          yImagePositionPatientControl === yImagePositionPatient &&
+          zImagePositionPatientControl === zImagePositionPatient){
+        return false;
+      }
+    }
+  }
 
   return displaySet.isReconstructable;
 };