PET images appear black/red (SUV not calculated)

Applies to: PET/CT and PET/MR
Typical symptom: the PET series looks uniformly dark/black/red, or the intensity scale is locked at 0 because a Standardized Uptake Value (SUV) could not be computed.

Why this happens

SliceVault scales PET data using SUVbw (body-weight–normalized SUV).
If SUV cannot be determined, the viewer has no meaningful intensity scale, and the PET series may appear black.

SliceVault determines SUV in two ways:

1. Pre-computed SUV factor (vendor private tag)
   Some PET series include a vendor-specific SUV factor, most often seen in scans from Philips Healthcare. SliceVault looks for this in the private tag (7053,1000). When the tag is present, and the fields (0054,1001) Units is CNTS and (0018,1075) Radionuclide Half Life is set, SliceVault decodes the factor and applies it directly.

2. On-the-fly SUV calculation
   When no usable pre-computed SUV factor is present, SliceVault calculates SUVbw from standard DICOM fields:

   

   with decay correction of the injected dose back to imaging time using the radionuclide half-life.

   DICOM tags SliceVault needs for PET SUV

   These tags must exist on the PET series (not only the CT):

   DICOM Tag	Location	VR	Notes
   (0010,1030) Patient Weight	Top level	DS	Value in kilograms
   (0008,0031) Series Time	Top level	TM	Used if applicable
   (0008,0032) Acquisition Time	Top level	TM	Required if Series Time is not applicable
   (0054,1001) Units	Top level	CS	Must be BQML
   (0054,0016) Radiopharmaceutical Information Sequence	Sequence	SQ	Contains the fields below
   (0018,1072) Radiopharmaceutical Start Time	In (0054,0016)	TM	Time of injection
   (0018,1074) Radionuclide Total Dose	In (0054,0016)	DS	Value in becquerels
   (0018,1075) Radionuclide Half Life	In (0054,0016)	DS	Value in seconds

   If any required tag is missing or invalid (e.g. weight = 0, half-life = 0, dose missing, inconsistent times), SUV calculation fails and the PET series may render black.

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How to fix at the source (scanner/export)

• Enable Radiopharmaceutical Information Sequence on PET export.
• Ensure series time, total dose (Bq), and half-life (s) are exported.
• Record patient weight before acquisition.
• If your site uses the vendor SUV factor, make sure it is exported.
• Avoid anonymization steps that strip PET-specific tags — let SliceVault handle de-identification.