diff --git a/monai/auto3dseg/analyzer.py b/monai/auto3dseg/analyzer.py
index a731546a9e..2f6e3857ef 100644
--- a/monai/auto3dseg/analyzer.py
+++ b/monai/auto3dseg/analyzer.py
@@ -255,36 +255,46 @@ def __call__(self, data):
         restore_grad_state = torch.is_grad_enabled()
         torch.set_grad_enabled(False)
 
-        ndas = [d[self.image_key][i] for i in range(d[self.image_key].shape[0])]
-        if "nda_croppeds" not in d:
-            nda_croppeds = [get_foreground_image(nda) for nda in ndas]
-
-        # perform calculation
-        report = deepcopy(self.get_report_format())
-
-        report[ImageStatsKeys.SHAPE] = [list(nda.shape) for nda in ndas]
-        report[ImageStatsKeys.CHANNELS] = len(ndas)
-        report[ImageStatsKeys.CROPPED_SHAPE] = [list(nda_c.shape) for nda_c in nda_croppeds]
-        report[ImageStatsKeys.SPACING] = (
-            affine_to_spacing(data[self.image_key].affine).tolist()
-            if isinstance(data[self.image_key], MetaTensor)
-            else [1.0] * min(3, data[self.image_key].ndim)
-        )
+        try:
+            ndas = [d[self.image_key][i] for i in range(d[self.image_key].shape[0])]
+            if "nda_croppeds" not in d:
+                nda_croppeds = [get_foreground_image(nda) for nda in ndas]
+            else:
+                nda_croppeds = d["nda_croppeds"]
+                if not isinstance(nda_croppeds, (list, tuple)) or len(nda_croppeds) != len(ndas):
+                    raise ValueError(
+                        f"Pre-computed 'nda_croppeds' must be a list with one entry per image channel "
+                        f"(expected {len(ndas)}, got "
+                        f"{len(nda_croppeds) if isinstance(nda_croppeds, (list, tuple)) else type(nda_croppeds).__name__})."
+                    )
+
+            # perform calculation
+            report = deepcopy(self.get_report_format())
+
+            report[ImageStatsKeys.SHAPE] = [list(nda.shape) for nda in ndas]
+            report[ImageStatsKeys.CHANNELS] = len(ndas)
+            report[ImageStatsKeys.CROPPED_SHAPE] = [list(nda_c.shape) for nda_c in nda_croppeds]
+            report[ImageStatsKeys.SPACING] = (
+                affine_to_spacing(data[self.image_key].affine).tolist()
+                if isinstance(data[self.image_key], MetaTensor)
+                else [1.0] * min(3, data[self.image_key].ndim)
+            )
 
-        report[ImageStatsKeys.SIZEMM] = [
-            a * b for a, b in zip(report[ImageStatsKeys.SHAPE][0], report[ImageStatsKeys.SPACING])
-        ]
+            report[ImageStatsKeys.SIZEMM] = [
+                a * b for a, b in zip(report[ImageStatsKeys.SHAPE][0], report[ImageStatsKeys.SPACING])
+            ]
 
-        report[ImageStatsKeys.INTENSITY] = [
-            self.ops[ImageStatsKeys.INTENSITY].evaluate(nda_c) for nda_c in nda_croppeds
-        ]
+            report[ImageStatsKeys.INTENSITY] = [
+                self.ops[ImageStatsKeys.INTENSITY].evaluate(nda_c) for nda_c in nda_croppeds
+            ]
 
-        if not verify_report_format(report, self.get_report_format()):
-            raise RuntimeError(f"report generated by {self.__class__} differs from the report format.")
+            if not verify_report_format(report, self.get_report_format()):
+                raise RuntimeError(f"report generated by {self.__class__} differs from the report format.")
 
-        d[self.stats_name] = report
+            d[self.stats_name] = report
+        finally:
+            torch.set_grad_enabled(restore_grad_state)
 
-        torch.set_grad_enabled(restore_grad_state)
         logger.debug(f"Get image stats spent {time.time() - start}")
         return d
 
diff --git a/tests/apps/test_auto3dseg.py b/tests/apps/test_auto3dseg.py
index 6c840e944d..1b41e84ef4 100644
--- a/tests/apps/test_auto3dseg.py
+++ b/tests/apps/test_auto3dseg.py
@@ -539,6 +539,43 @@ def test_seg_summarizer(self):
         assert str(DataStatsKeys.FG_IMAGE_STATS) in report
         assert str(DataStatsKeys.LABEL_STATS) in report
 
+    def test_image_stats_precomputed_nda_croppeds(self):
+        """Verify ImageStats handles pre-populated nda_croppeds without crashing.
+
+        Previously raised UnboundLocalError because nda_croppeds was only assigned
+        inside the ``if "nda_croppeds" not in d`` branch but used unconditionally.
+        """
+        analyzer = ImageStats(image_key="image")
+        image = torch.rand(1, 10, 10, 10)
+        precomputed = [np.random.rand(8, 8, 8)]  # simulated pre-cropped foreground
+        data = {"image": MetaTensor(image), "nda_croppeds": precomputed}
+        result = analyzer(data)
+        assert "image_stats" in result
+        assert verify_report_format(result["image_stats"], analyzer.get_report_format())
+
+    def test_analyzer_grad_state_restored_after_call(self):
+        """Verify ImageStats restores torch grad-enabled state on both normal and disabled entry.
+
+        Checks that the try/finally guard correctly restores the state regardless of
+        whether grad was enabled or disabled before the call.
+        """
+        analyzer = ImageStats(image_key="image")
+        image = torch.rand(1, 10, 10, 10)
+        data = {"image": MetaTensor(image)}
+
+        # grad enabled before call → must still be enabled after
+        torch.set_grad_enabled(True)
+        analyzer(data)
+        assert torch.is_grad_enabled(), "grad state was not restored after ImageStats call"
+
+        # grad disabled before call → must still be disabled after
+        torch.set_grad_enabled(False)
+        try:
+            analyzer(data)
+            assert not torch.is_grad_enabled(), "grad state was not restored after ImageStats call"
+        finally:
+            torch.set_grad_enabled(True)  # always restore for subsequent tests
+
     def tearDown(self) -> None:
         self.test_dir.cleanup()