An interventional medical device is provided that incorporates a forward-directed ultrasound imaging system integrated into a single minimally invasive device. The medical device can be in the form of an image guided catheter having a replaceable and reusable ultrasound imaging assemble and replaceable interventional devices such as a removable introducer needle and syringe, the device having a tapered distal tip, particularly those suitable for minimally invasive direct introduction into the human or other mammalian body. The imaging system comprises one or more small ultrasound transducers that can be replaceably integrated into the device via a longitudinal slot in an expendable elongate body and may be inserted into and removed from the device to customize the device for a particular use. An ultrasound system can be provided in the device either alone or in combination with fiber optic imaging to provide a range of forward imaging and therapeutic capabilities of the device for direct access to a target site from the skin via the removable introducer needle.