Sample code to read values from sequences. Should be incorporated into core to handle it natively.

read_sequences_nanodicom.php

<?php
require 'Nanodicom/nanodicom.php';
$filename = 'test.DCM';

$dicom = Nanodicom::factory($filename);
$dicom->parse(array(array(0x0010, 0x0010), array(0x0054, 0x0016)));

// Get the sequence
$seq   = $dicom->value(0x0054, 0x0016);
// Get the items (sequences are grouped in items)
$items = $dicom->dataset_value($seq, 0xFFFE, 0xE000);
// Get the value wanted
$val   = $dicom->dataset_value($items, 0x0018, 0x0031);
var_dump($val);

unset($dicom);