PHP Filter multidimensional-array key with another array

What I'm trying to do is read in a worksheet from an excel file and only keep certain columns based on a list in another array. I able to read in the excel sheet using PHPExcel, but haven't been successfully filtering out the unwanted column keys. I have been searching the web and been trying to apply the following: array_intersect_key, functions, array_filter and no success.

      <?php

    /** Include path **/
    set_include_path(get_include_path() . PATH_SEPARATOR . '../../../Classes/');

    /** PHPExcel_IOFactory */
    include 'PHPExcel/IOFactory.php';


    //$inputFileType = 'Excel5';
    //  $inputFileType = 'Excel2007';
    //  $inputFileType = 'Excel2003XML';
    //  $inputFileType = 'OOCalc';
    //  $inputFileType = 'Gnumeric';
    $inputFileName = './sampleData/example1.xls';
    $sheetname = 'Visual';

    $inputFileType = PHPExcel_IOFactory::identify($inputFileName);
    echo 'Loading file ',pathinfo($inputFileName,PATHINFO_BASENAME),' using IOFactory with a defined reader type of ',$inputFileType,'<br />';
    $objReader = PHPExcel_IOFactory::createReader($inputFileType);
    echo 'Loading Sheet "',$sheetname,'" only<br />';
    $objReader->setLoadSheetsOnly($sheetname);
    $objPHPExcel = $objReader->load($inputFileName);


    echo '<hr />';

    echo $objPHPExcel->getSheetCount(),' worksheet',(($objPHPExcel->getSheetCount() == 1) ? '' : 's'),' loaded<br /><br />';
    $loadedSheetNames = $objPHPExcel->getSheetNames();
    foreach($loadedSheetNames as $sheetIndex => $loadedSheetName) {
        echo $sheetIndex,' -> ',$loadedSheetName,'<br />';
    }

    $sheetData = $objPHPExcel->getActiveSheet()->toArray(null,true,true,true);

    // Removes NULL values
    foreach($sheetData as $key => &$row) {
        $row = array_filter($row,function($cell){return !is_null($cell);});
        if (count($row) == 0) {
            unset($sheetData[$key]);
        }
    }
    unset ($row);

    unset ($sheetData[1]); // Remove row 1 of spreadsheet 
    unset ($sheetData[2]); // Remove row 2 of spreadsheet

    // columns what to keep, this is just example
    $col_keep = array('A', 'B', 'D', 'K');

    foreach($sheetData as $k=>$v) {
      foreach($v as $c=>$vb){
      echo "$c<br>"; // this display the columns keys e.g A,B,C,etc... 
      // How to filter here with array $col_keep?        
      }
    }

     ?>