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Medical Forum / Diseases and Disorders / Prostate Cancer / May 2004Prostate Volume?
Can someone help me with this? I would like to calculate my prostate volume. My CT scan indicated that my prostate was "slightly enlarged" and that it measured 5.8 x 4.0 x 4.5 cm. If I multiply that out, I get 104.4, but that seems too high. I vaguely remember reading that there was another factor that needed to be used in the calculation, but I don't remember what it was. > Can someone help me with this? I would like to calculate my prostate > volume. My CT scan indicated that my prostate was "slightly enlarged" > and that it measured 5.8 x 4.0 x 4.5 cm. If I multiply that out, I > get 104.4, but that seems too high. I vaguely remember reading that > there was another factor that needed to be used in the calculation, > but I don't remember what it was. In addition to the three dimensions, you'd also need to know the shape in order to calculate the volume. If the prostate was shaped like a rectangular solid (i.e., like a brick), you could multiply the three numbers to get the volume. But it's not shaped like that. If it were spherical (which it can't be with those dimensions), I think the formula would be pi * radius cubed. I don't know the exact shape and don't know if it's the same for every man or not. Alan Glenn: I cannot help you with the math, sorry, but I do remember that my prostate was 30 grams. There was some discussion at the time that one measure was volume and the other weight. And, for some reason that I forgot (which happens all too often these days) there was a reason why the two both were the same value within this range, i.e., both were at 30 xx. Anyway, my uro said that mine, at 30, was "a big one". But I have seen guys here with prostates at 60 grams, so who knows how big it can get? Sorry I could not answer your question, but I will look forward to reading the answer. Thank you. David S. > Can someone help me with this? I would like to calculate my prostate > volume. My CT scan indicated that my prostate was "slightly enlarged" > and that it measured 5.8 x 4.0 x 4.5 cm. If I multiply that out, I > get 104.4, but that seems too high. I vaguely remember reading that > there was another factor that needed to be used in the calculation, > but I don't remember what it was. Hi David...I wondered about "average" too after my prostate was removed. If human tissue has a density around 1, then volume and weight would be about the same. The following paper, while raising some intriguing questions of its own, suggests that "average" prostate size is between 30 and 50 cm^3...Best wishes and good health, Ron Prostate. 1999 Feb 1;38(2):144-50. Differences in prostate size between patients from University and Veterans Affairs Medical Center populations. Nixon RG, Meyer GE, Brawer MK. University of Washington School of Medicine, Seattle, USA. BACKGROUND: Numerous studies on prostatic disease have been performed at Veterans Affairs (VA) Medical Centers. Recent investigations evaluating early detection of prostate cancer provide insight that the average prostate volume may be different between patients with similar clinical findings who are from different hospital settings. The objective of this study was to compare prostate size between men from University and VA Medical Centers. METHODS: Patients were enrolled retrospectively from 1989-1996 from the Urology Clinics at a University and a VA Medical Center. All men underwent transrectal ultrasound-guided sextant biopsy of the prostate owing to either an elevated prostate-specific antigen (PSA) level and/or abnormal digital rectal examination (DRE) detected prior to biopsy. Prostate volume was calculated using the ellipsoid three-diameter formula based on transrectal ultrasound measurements. RESULTS: There were 1,311 men included in the analysis: 717 were from the VA, and 594 were from the University. The average prostate volume was significantly smaller among VA patients both for men with cancer (P = 0.0004) and for men with no evidence of malignancy (P < 0.0001). Overall, the average prostate volume was 38.5 cm3 (median, 32.5 cm3) among men from the VA compared to 46.8 cm3 (median, 39.3 cm3) among men from the University Medical Center. Men from the VA were older (mean +/- SD = 68 +/- 7.3) than men from the University (mean +/- SD = 66 +/- 7.7) (P = 0.004) and there was no significant difference in PSA levels between the two groups of patients (P = 0.11). Intriguingly, the incidence of cancer was significantly lower at the VA (24.5%) compared to the University (35.9%) (P < 0.0001). CONCLUSIONS: The variance in prostate size suggests that there are significant differences between the two patient populations. Proposed factors leading to this discrepancy include differences in socioeconomic factors, environmental factors, and changes in hormonal milieu related to alcohol and tobacco use. These results may have significant implications regarding the interpretation and extrapolation of results from previous studies performed at a single hospital setting. > Glenn: > I cannot help you with the math, sorry, but I do remember that my [quoted text clipped - 8 lines] > Thank you. > David S. Glenn, Multiply your answer by pi/6. There is and inherent error though that often underestimates the correct size. Ron Spane Glen, Ron is correct, the volume is generally computed as a prolate ellipsoid, close but not exact due to irregularities V= l*w*h*p/6, the volume, based on your dimensions is about 55 cc. I hope this helps. Tom > Glenn, > > Multiply your answer by pi/6. There is and inherent error though that > often underestimates the correct size. > > Ron Spane OK, now I get 54.7. After I posted this, I went back and checked my notes, and when I met with the radiation oncologist, he referred to the CT scan as showing a prostate of 54 grams, so that checks out. My copy of "PC for Dummies" sez that the prostate is about 30 grams or more in men 50+ (I'm 46 tomorrow), but they can go up to 100g. Not surprisingly, my flow rate is poor (8). > Glenn, > > Multiply your answer by pi/6. There is and inherent error though that > often underestimates the correct size. > > Ron Spane Glenn, Now you've got me confused, a gram is a measure of weight, a centimeter-length, a cubic centimeter-volume. Is the prostate gland unique in that it's weight in grams is equal to it's volume in cubic centimeters.I'm a civil engineer with no medical training and have trouble understanding the cross reference, apples and oranges. For example: Sawdust weighs 210kg/cu.m. where Seawater is 1026kg/cu.m., therefore: unless the prostate gland has that unique property, I fail to see where weight = volume. Perhaps someone can enlighten me, I've never been opposed to learning something new. Tom > OK, now I get 54.7. After I posted this, I went back and checked my > notes, and when I met with the radiation oncologist, he referred to [quoted text clipped - 10 lines] > > > > Ron Spane > Glenn, > > Now you've got me confused, a gram is a measure of weight, a > centimeter-length, a cubic centimeter-volume. Is the prostate gland unique > in that it's weight in grams is equal to it's volume in cubic > centimeters Tom, the key assumption being made here is that the prostate gland, like most non-bony organs in the body, tends to have a density close to that of water, or 1 g/cc. Thus, 54cc X 1.0g/cc = 54 g. Of course, this is only an approximation, because we don't know the precise density, but it gets us in the ball park. To those who were wondering where the ? /6 factor comes from: A sphere with a radius of 1 cm has a volume of ? (4/3) cubic cm, and fits in a cube 2 cm on a side, with a volume of 8 cubic cm. We divide the volume of the sphere by the volume of the cube: (? (4/3)/8) = ? /6. Ernie The question marks were supposed to be pi symbols. Hey, it looked good before I hit "send." Ernie >Subject: Re: Prostate Volume? >From: "Tom C" thomcu@verizon.net [quoted text clipped - 4 lines] > >Now you've got me confused, a gram is a measure of weight, a Ouch. A gram is a measure of mass, not weight. The density of the human body is slightly greater than 1 g/cc which is why you float with just a little air in your lungs. Fat is a little less dense and muscle a little more, which is why lean muscular people don't float well. The volume of a sphere is (4/3)*pi*( r squared). >centimeter-length, a cubic centimeter-volume. Is the prostate gland unique >in that it's weight in grams is equal to it's volume in cubic [quoted text clipped - 23 lines] >> > >> > Ron Spane Isn't it 4/3*pi*r cubed vice squared? Well, happy birthday Glenn!  SignatureProstate Cancer Survivor (so far), not a doctor PSA 16 10/17/2000 @ 46 Biopsy 11/01/2000 G7 (3+4), T2c RRP 12/15/2000 PSA .1 .1 .1 .27 .37 .75 EBRT 05-07/2002 @ 47 PSA .34 .22 .15 .21 .32 Erection 05/12/2003 @ 48 HTbegins 07/21/2003 @ 48 PSA .07 .05 Lupron 7/03, 8/03, 12/03, 4/04 > OK, now I get 54.7. After I posted this, I went back and checked my > notes, and when I met with the radiation oncologist, he referred to [quoted text clipped - 10 lines] > > > > Ron Spane hi glenn - i wish i could help on your question, but can you call the CT dept and maybe get an answer? i know that when i had my biopsy done, it had in the upper corner on the screen the size of the prostate gland. it said, "29.4 grams" but when they pulled it out and threw it on the path table, that bad boy weighed in at 55 grams - almost twice the size as the ultrasound said. so, there you have it. did the ultrasound not pick up something? i don't know. i keep coming up with more questions and less answers. ~ curtis knowledge is power - growing old is mandatory - growing wise is optional "Many more men die with prostate cancer than of it. Growing old is invariably fatal. Prostate cancer is only sometimes so." Glenn, For a comparison and considering all prostates are not the same shape, my numbers were; 6 x 5.5 x 5 cm and weight was 65.5 grams post-op. I had a transrectal ultrasound that measured my volume as 62.4 ccs Ron Spane >Subject: Re: Prostate Volume? >From: "ronju99" res0rbp6@nospam.verizon.net [quoted text clipped - 7 lines] > >Ron Spane Note that treating this as a rectangular box gives a volume of 167.5 cc which means you divide it by about 2.2 And also, the prostate would almost float in water according to this. Hi Glenn...Ron S. is right on with his pi/6 remarks...Best wishes and good health, Ron Korean J Radiol. 2000 Apr-Jun;1(2):110-3 Prostate volume measurement by TRUS using heights obtained by transaxial and midsagittal scanning: comparison with specimen volume following radical prostatectomy. Park SB, Kim JK, Choi SH, Noh HN, Ji EK, Cho KS. Department of Radiology, University of Ulsan College of Medicine, Seoul, Korea. OBJECTIVE: The purpose of this study was to determine, when measuring prostate volume by TRUS, whether height is more accurately determined by transaxial or midsagittal scanning. MATERIALS AND METHODS: Sixteen patients who between March 1995 and March 1998 underwent both preoperative TRUS and radical prostatectomy for prostate cancer were included in this study. Using prolate ellipse volume calculation (height x length x width x pi/6), TRUS prostate volume was determined, and was compared with the measured volume of the specimen. RESULTS: Prostate volume measured by TRUS, regardless of whether height was determined transaxially or midsagittally, correlated closely with real specimen volume. When height was measured in one of these planes, a paired t test revealed no significant difference between TRUS prostate volume and real specimen volume (p =.411 and p =.740, respectively), nor were there significant differences between the findings of transaxial and midsagittal scanning (p =.570). A paired sample test, however, indicated that TRUS prostate volumes determined transaxially showed a higher correlation coefficient (0.833) and a lower standard deviation (9.04) than those determined midsagittally (0.714 and 11.48, respectively). CONCLUSION: Prostate volume measured by TRUS closely correlates with real prostate volume. Furthermore, we suggest that when measuring prostate volume in this way, height is more accurately determined by transaxial than by midsagittal scanning. > Can someone help me with this? I would like to calculate my prostate > volume. My CT scan indicated that my prostate was "slightly enlarged" > and that it measured 5.8 x 4.0 x 4.5 cm. If I multiply that out, I > get 104.4, but that seems too high. I vaguely remember reading that > there was another factor that needed to be used in the calculation, > but I don't remember what it was. |
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