RF: Use csa_header package to parse Siemens CSA headers

src/dcmstack/extract.py

@@ -13,7 +13,7 @@
 from pydicom.dataset import PrivateBlock
 from pydicom.datadict import keyword_for_tag, tag_for_keyword, private_dictionaries
 from pydicom.charset import decode_element
-from nibabel.nicom import csareader
+from csa_header import CsaHeader
 
 from .dcmstack import DicomStack
 
@@ -89,188 +89,42 @@ def ignore_except(tag, name, ds):
 the function which takes the DICOM element and returns a dictionary.'''
 
 
-def simplify_csa_dict(csa_dict):
-    '''Simplify the result of nibabel.nicom.csareader.
+def parse_csa(raw_bytes):
+    '''Simplify the result of csa_header.CsaHeader
 
     Parameters
     ----------
     csa_dict : dict
-        The result from nibabel.nicom.csareader
+        The result from csa_header.CsaHeader
 
     Returns
     -------
     result : dict
-        Result where the keys come from the 'tags' sub dictionary of `csa_dict`.
-        The values come from the 'items' within that tags sub sub dictionary.
-        If items has only one element it will be unpacked from the list.
+        Simpler key -> value mapping
     '''
+    csa_dict = CsaHeader(raw_bytes).read()
     if csa_dict is None:
         return None
-
     result = {}
-    for tag in sorted(csa_dict['tags']):
-        items = []
-        for item in csa_dict['tags'][tag]['items']:
-            if isinstance(item, bytes):
-                try:
-                    item = item.decode()
-                except UnicodeDecodeError:
-                    item = ""
-            items.append(item)
-        if len(items) == 0:
+    for key, elem in csa_dict.items():
+        val = elem['value']
+        if val is None:
             continue
-        elif len(items) == 1:
-            result[tag] = items[0]
-        else:
-            result[tag] = items
+        result[key] = val
     return result
 
 
-def csa_image_trans_func(elem):
-    '''Function for translating the CSA image sub header.'''
-    return simplify_csa_dict(csareader.read(elem.value))
-
-
 csa_image_trans = Translator('CsaImage',
                              pydicom.tag.Tag(0x29, 0x1010),
                              'SIEMENS CSA HEADER',
-                             csa_image_trans_func)
+                             parse_csa)
 '''Translator for the CSA image sub header.'''
 
 
-class PhoenixParseError(Exception):
-    def __init__(self, line):
-        '''Exception indicating a error parsing a line from the Phoenix
-        Protocol.
-        '''
-        self.line = line
-
-    def __str__(self):
-        return 'Unable to parse phoenix protocol line: %s' % self.line
-
-
-def _parse_phoenix_line(line, str_delim='""'):
-    delim_len = len(str_delim)
-    #Handle most comments (not always when string literal involved)
-    comment_idx = line.find('#')
-    if comment_idx != -1:
-        #Check if the pound sign is in a string literal
-        if line[:comment_idx].count(str_delim) == 1:
-            if line[comment_idx:].find(str_delim) == -1:
-                raise PhoenixParseError(line)
-        else:
-            line = line[:comment_idx]
-
-    #Allow empty lines
-    if line.strip() == '':
-        return None
-
-    #Find the first equals sign and use that to split key/value
-    equals_idx = line.find('=')
-    if equals_idx == -1:
-        raise PhoenixParseError(line)
-    key = line[:equals_idx].strip()
-    val_str = line[equals_idx + 1:].strip()
-
-    #If there is a string literal, pull that out
-    if val_str.startswith(str_delim):
-        end_quote = val_str[delim_len:].find(str_delim) + delim_len
-        if end_quote == -1:
-            raise PhoenixParseError(line)
-        elif not end_quote == len(val_str) - delim_len:
-            #Make sure remainder is just comment
-            if not val_str[end_quote+delim_len:].strip().startswith('#'):
-                raise PhoenixParseError(line)
-
-        return (key, val_str[2:end_quote])
-
-    else: #Otherwise try to convert to an int or float
-        val = None
-        try:
-            val = int(val_str)
-        except ValueError:
-            pass
-        else:
-            return (key, val)
-
-        try:
-            val = int(val_str, 16)
-        except ValueError:
-            pass
-        else:
-            return (key, val)
-
-        try:
-            val = float(val_str)
-        except ValueError:
-            pass
-        else:
-            return (key, val)
-
-    raise PhoenixParseError(line)
-
-
-def parse_phoenix_prot(prot_key, prot_val):
-    '''Parse the MrPheonixProtocol string.
-
-    Parameters
-    ----------
-    prot_str : str
-        The 'MrPheonixProtocol' string from the CSA Series sub header.
-
-    Returns
-    -------
-    prot_dict : dict
-        Meta data pulled from the ASCCONV section.
-
-    Raises
-    ------
-    PhoenixParseError : A line of the ASCCONV section could not be parsed.
-    '''
-    if prot_key == 'MrPhoenixProtocol':
-        str_delim = '""'
-    elif prot_key == 'MrProtocol':
-        str_delim = '"'
-    else:
-        raise ValueError('Unknown protocol key: %s' % prot_key)
-    ascconv_start = prot_val.find('### ASCCONV BEGIN ')
-    ascconv_end = prot_val.find('### ASCCONV END ###')
-    ascconv = prot_val[ascconv_start:ascconv_end].split('\n')[1:-1]
-
-    result = {}
-    for line in ascconv:
-        parse_result = _parse_phoenix_line(line, str_delim)
-        if parse_result:
-            result[parse_result[0]] = parse_result[1]
-
-    return result
-
-
-def csa_series_trans_func(elem):
-    '''Function for parsing the CSA series sub header.'''
-    csa_dict = simplify_csa_dict(csareader.read(elem.value))
-
-    #If there is a phoenix protocol, parse it and dump it into the csa_dict
-    phx_src = None
-    if 'MrPhoenixProtocol' in csa_dict:
-        phx_src = 'MrPhoenixProtocol'
-    elif 'MrProtocol' in csa_dict:
-        phx_src = 'MrProtocol'
-
-    if not phx_src is None:
-        phoenix_dict = parse_phoenix_prot(phx_src, csa_dict[phx_src])
-        del csa_dict[phx_src]
-        for key, val in phoenix_dict.items():
-            new_key = '%s.%s' % ('MrPhoenixProtocol', key)
-            csa_dict[new_key] = val
-
-    return csa_dict
-
-
 csa_series_trans = Translator('CsaSeries',
                               pydicom.tag.Tag(0x29, 0x1020),
                               'SIEMENS CSA HEADER',
-                              csa_series_trans_func)
+                              parse_csa)
 '''Translator for parsing the CSA series sub header.'''
 
 

src/dcmstack/info.py

@@ -27,6 +27,7 @@
                     'nibabel >= 5.3.1',
                     'pylibjpeg[all] ; python_version >= "3.8"',
                     'pint',
+                    'git+https://github.com/open-dicom/csa_header.git#egg=csa_header',
                    ]
 
 # Extra requirements for building documentation and testing