diff --git a/pydatalab/pydatalab/apps/mri/blocks.py b/pydatalab/pydatalab/apps/mri/blocks.py
index 69c2b6abf..8ec11d511 100644
--- a/pydatalab/pydatalab/apps/mri/blocks.py
+++ b/pydatalab/pydatalab/apps/mri/blocks.py
@@ -3,14 +3,15 @@
 import pandas as pd
 
 from pydatalab.blocks.base import DataBlock
-from pydatalab.bokeh_plots import mytheme
+from pydatalab.logger import LOGGER
+from pydatalab.bokeh_plots import DATALAB_BOKEH_THEME
 from pydatalab.file_utils import get_file_info_by_id
 
 
 class MRIBlock(DataBlock):
     blocktype = "mri"
     description = "In situ MRI"
-    accepted_file_extensions = (".csv", "2dseq")
+    accepted_file_extensions = (".csv", "2dseq", "visu_pars")
 
     @property
     def plot_functions(self):
@@ -18,10 +19,10 @@ def plot_functions(self):
 
     @classmethod
     def load_2dseq(
-        self,
+        cls,
         location: str,
         image_size: tuple[int, int] = (512, 512),
-    ) -> pd.DataFrame:
+    ) -> list[np.ndarray]:
         if not isinstance(location, str):
             location = str(location)
 
@@ -38,20 +39,28 @@ def load_2dseq(
             for i in range(num_images):
                 # grab an image_size square slice from arrays
                 image_arrays.append(
-                    arr[i * image_pixels : (i + 1) * image_pixels].reshape(*image_size)
+                    arr[i * image_pixels : (i + 1) * image_pixels].reshape(*image_size).copy()
                 )
 
         return image_arrays
 
-    def generate_mri_plots(self):
+    def generate_mri_plot(self):
+        """Generate image plots of MRI data."""
+        from bokeh.layouts import column
+        from bokeh.models import ColumnDataSource, CustomJS, Slider, ColorBar, LinearColorMapper
+        from bokeh.plotting import figure
+
+        if "file_id" not in self.data:
+            return None
         file_info = get_file_info_by_id(self.data["file_id"], update_if_live=True)
 
         image_array = self.load_2dseq(
             file_info["location"],
         )
-        from bokeh.layout import column
-        from bokeh.models import ColumnDataSource, CustomJS, Slider
-        from bokeh.plotting import figure
+
+        if len(image_array) == 0:
+            raise RuntimeError(f"Could not find any images in {file_info['location']}")
+            return None
 
         p = figure(
             sizing_mode="scale_width",
@@ -61,6 +70,10 @@ def generate_mri_plots(self):
         )
 
         image_source = ColumnDataSource(data={"image": [image_array[0]]})
+
+        cmap = bokeh.palettes.Viridis256
+        color_mapper = bokeh.models.LogColorMapper(palette=cmap, low=1, high=np.max(image_array))
+
         p.image(
             image="image",
             source=image_source,
@@ -68,22 +81,35 @@ def generate_mri_plots(self):
             y=0,
             dw=10,
             dh=10,
-            palette="Sunset11",
-            level="image",
+            color_mapper=color_mapper,
         )
 
-        slider = Slider(start=0, end=len(image_array), step=1, value=0, title="Select image")
+        p.axis.visible = False
+        p.xgrid.visible = False
+        p.ygrid.visible = False
+
+        # Set limits to edge of images defined by 10x10
+        p.x_range.start = 0
+        p.x_range.end = 10 
+        p.y_range.start = 0
+        p.y_range.end = 10
+
+        color_bar = ColorBar(color_mapper=color_mapper)
+
+        slider = Slider(start=0, end=len(image_array) - 1, step=1, value=0, title=f"Select image ({len(image_array)} images)")
 
         slider_callback = CustomJS(
-            args=dict(image_source=image_source, slider=slider),
+            args=dict(image_source=image_source, image_array=image_array, slider=slider),
             code="""
 var selected_image_index = slider.value;
-image_source.data["image"] = [image_arrays[selected_image_index]];
+image_source.data["image"] = [image_array[selected_image_index]];
 image_source.change.emit();
 """,
         )
         slider.js_on_change("value", slider_callback)
 
+        p.add_layout(color_bar, "right")
+
         layout = column(slider, p)
 
-        self.data["bokeh_plot_data"] = bokeh.embed.json_item(layout, theme=mytheme)
+        self.data["bokeh_plot_data"] = bokeh.embed.json_item(layout, theme=DATALAB_BOKEH_THEME)
diff --git a/pydatalab/pydatalab/routes/v0_1/blocks.py b/pydatalab/pydatalab/routes/v0_1/blocks.py
index d9a005c85..1d3a0c450 100644
--- a/pydatalab/pydatalab/routes/v0_1/blocks.py
+++ b/pydatalab/pydatalab/routes/v0_1/blocks.py
@@ -139,17 +139,30 @@ def _save_block_to_db(block: DataBlock) -> bool:
     overwriting previous data saved there.
     returns true if successful, false if unsuccessful
     """
-    if block.data.get("item_id"):
+
+    updated_block = block.to_db()
+    update = {"$set": {f"blocks_obj.{block.block_id}": updated_block}}
+
+    print(updated_block.keys())
+
+    if block.data.get("collection_id"):
+        match = {"collection_id": block.data["collection_id"], **get_default_permissions(user_only=False)}
+    else:
+        match = {"block_id": block.data["block_id"], **get_default_permissions(user_only=False)}
+
+    
+    try:
         result = flask_mongo.db.items.update_one(
-            {"item_id": block.data["item_id"], **get_default_permissions(user_only=False)},
-            {"$set": {f"blocks_obj.{block.block_id}": block.to_db()}},
+            match,
+            update,
         )
-    elif block.data.get("collection_id"):
-        result = flask_mongo.db.collections.update_one(
-            {"item_id": block.data["collection_id"], **get_default_permissions(user_only=False)},
-            {"$set": {f"blocks_obj.{block.block_id}": block.to_db()}},
+    except pymongo.errors.DocumentTooLarge:
+        LOGGER.warning(
+            f"_save_block_to_db failed, trying to strip down the block plot to fit in the 16MB limit"
         )
 
+        return False
+
     if result.matched_count != 1:
         LOGGER.warning(
             f"_save_block_to_db failed, likely because item_id ({block.data.get('item_id')}), collection_id ({block.data.get('collection_id')}) and/or block_id ({block.block_id})  wasn't found"