 So here's our introductory case, a 63 year old man who has an accidental or incidental PSA of over 40 at a health fair and then goes to see his physician as an abnormal examination and an abnormal MRI. On the right side of the gland there is diffuse intermediate signal intensity that is showing the charcoal or a racer side in the right portion of the gland, but the heterogeneous signal intensity that we see in the left portion of the gland. Let's take on a little bit of anatomy for a moment. This sharp interface of a darker area towards the midline from here to here in the normal left part of the gland is known as the central region of the prostate. Within this region lies the transitional zone, which is more around the urethra, and the central zone, both incorporated into this central region. The outer portion of the prostate, and let's scroll it a little bit so we can look at it from top to bottom, the outer portion of the prostate which goes all the way down to the bottom of the prostate, we're going low, and then when we go low then we go high. This portion of the prostate, more hyper intense, more curvilinear is known as the peripheral zone. The demarcation between this portion of the prostate, the central region, and the peripheral portion of the prostate, or peripheral zone, is known as the surgical capsule, so that's the surgical capsule. On the right side you don't see the surgical capsule because it's been erased or transgressed by our dark, smudgy charcoal sign tumor, which we'll learn is a very important anatomic and signal sign of cancer. On the left side we also see a sharp demarcation between the prostate gland, especially in this location where the dark signal intensity represents the anatomic capsule, but the brighter signal intensity represents the periprostatic venous plexus, which can be seen on the T1 weighted image as these slightly lobulated areas of intermediate signal intensity. The delicate, small dotted areas of signal alteration, perhaps best seen at the base of the prostate, up high near the bladder, is known as the neurovascular bundle. Here they are at the 7 o'clock and 5 o'clock position. The prostate is surrounded by fat. This darker, more anterior aspect of the prostate is known as the fibrovascular stroma, which is seen anteriorly and more developed and more conspicuous as you go low down into the prostate away from the bladder. The fibrovascular stroma gets a little more conspicuous as an isolated structure, but it's all the way up and down. There is another stroma, which is a little harder to see, this darker area up near the prostate base, let me go up higher, near the base right there, which is known as the muscular stroma. The muscular stroma can usually be found where the seminal vesicles come together. In the coronal projection, it looks like an inverted V, but we're not in the coronal projection. We're in the axial projection, and a common mistake is to confuse this muscular stroma with intermediate signal intensity cancer. Note that the bladder, which is urine containing, has exaggerated cellulation due to some prostatic hypertrophy. This very thin interface, right there, just anterior to my arrow, is the Dino-Villier fascia. There it is again, the Dino-Villier fascia, which separates the prostate from the rectum. On the right, we've got something called an ADC map, which is simply a map of the velocities that are mapped out pixel by pixel. More on this in later segments, but what this shows is a darker area in this map, which corresponds to restriction of motion of fluid in the prostate gland, which can be measured in micro millimeters per second. My only intention is just to have you get in the habit of comparing these all-important sequences, the T2 water-weighted sequence with the diffusion-weighted sequence, because this is the heart, the soul, and the guts of prostate MRI, unlike breast imaging, where the heart, the soul, and the guts of breast imaging is dynamic, contrast-enhanced, or DCE MRI. DCE MRI is used in prostate, but it's not the heart, the soul, and the guts of the MR. Let's move on now to the coronal projection, just for anatomic giggles. Let's find a nice coronal, and we have one right here in the center. I am not going to change it to a one-up configuration. I'm going to leave the axials up so you can see where we are, front to back. Here we are in the front, where things are a little bit darker, because we're volume averaging a combination of the tumor that has invaded the fibro vascular anterior stroma, especially in the mid and apical portion of the gland, which is very hard to get to, and see by transurethral ultrasound-guided biopsy, or with intracerectal ultrasound. Let's go back a ways all the way to the posterior aspect of the gland, where we see another dark nodular area. No, that's not cancer. That is the muscular stroma, where the ductus deferens and seminal vesicles converge. Sometimes it can be seen as an inverted V. Sometimes, as in this case, it can look a little bit nodular. We said that the prostate gland could be divided into a base near the base of the bladder and an apex down low. You've already seen that we can have an anterior gland, anterior gland, middle of the gland, and a posterior aspect of the gland. And these are going to get individual labels when we get to the Piratz 2.0 scoring system. We also, let's go to the very center of the gland. We said we can divide the gland up into a base and an apex, but also a central one-third. And that central one-third can be divided into the outer half, the lateral segment, and the medial half, the intermediate segment. And it's going to have a left side and a right side. In fact, the gland is always going to have a left side and a right side. So we're going to come up with cute little abbreviations like left, mid, lateral, PZ for this location. But that's coming shortly to a theater near you. Let's look at the sagittal projection now. And I'm going to still leave my axial images up. In fact, I'm going to put up my T2 image because it's a little better anatomically. And I'm going to blow up my image a little bit here. The test is down here. So this would be anterior. This would be posterior. I'm going to make it even a little bit bigger. I don't want you to get too disoriented. And I'm going to try and move it a little bit here. And there's your synthesis pubis. Maybe just a tiny bit bigger for you. And here is your prostate gland with your urethra. If you follow the axis of the urethra to about this point, everything's a little bit blurred because this patient has prostate cancer, but the central region, which is more heterogeneous, is going to contain the central zone and transitional zone. Here are the seminal vesicles converging on the prostate gland on either side, right side, left side. Now, even though this is a T2-weighted image, as you get a little bit older, the seminal vesicles are not going to be as bright as they would be when you're younger. And sometimes they're not bright at all. Unfortunately, when cancer infiltrates the seminal vesicles, it, too, will have an intermediate signal intensity very similar to the desiccation that occurs when you are an adult. Some of you are wondering what this bright signal intensity nodule represents. It's a prostate utricular cyst. In fact, in no way related to cancer, most cancers, unless it's the musinus variety, which is unusual or a cyst adenoma or a cyst adenocarcinoma of the prostate, are intermediate or darkened signal, not brightened signal, such as this smooth, round lesion located directly in the midline. No, this is a pitfall. It is not cancer. That's cancer right next to it. And we said that towards the back, we're going to have a muscular stroma, which we see near the base of the seminal vesicle. And in the front, we have a fibrovascular stroma, which goes all the way from the apex, gets a little less dark in the middle, and then dark again as we get back upwards towards the base. Now, to see the peripheral zone, you've got to be peripheral. So we want to be either at the very tippy top off to the side or completely off to the side. And here we are off to the left side. There is your peripheral zone encasing, like bread around a sandwich, encasing the central portions of the prostate gland. Unfortunately, when we go over to the opposite side, the encased peripheral zone is gone because it is completely obfuscated, infiltrated, and replaced by solid tumor. In the front, we have the fatty space of ritzius. Behind, we have the linear hypo intense signal, representing a combination of the volume-average capsule and the dinon-vilier fascia, which separates it from the adjacent rectum with a small amount of fat, the rectoprostatic fat. That concludes our introduction to prostate anatomy as seen by MRI in the coronal, the sagittal, and the axial projection. Let's keep going, shall we?