Results With The Gammaprobe Technique

The initial series of patients published in 1998 [3] has been updated for this chapter and now consists of 28 patients who have undergone radioguided biopsy of 31 ribs and one sternum. These 28 patients (13 men, 15 women) presented with a variety of known or suspected underlying primary cancers, as listed in Table 3. All had abnormal bone scintigrams but with normal plain radiographs. They all were either asymptomatic or had minimal, nonlocalizing symptoms.

Intraoperatively, the bone to be resected always appeared grossly normal to the surgeon. However, the surgical accuracy was 100%; all bones biopsied contained a pathological process that would account for the hot spot on the images. Table 4 lists the pathological diagnoses found with the 32 biopsies. Only seven of the 32 bones (21.9%) contained metastatic cancer (squamous cell carcinoma of the lung (2), lymphoma (2), adenocarcinoma of the lung, carcinoma of the prostate, and melanoma). The measurement of serum alkaline phosphatase was not very helpful because only two of the seven patients with osseous metastases had slightly elevated levels of this enzyme (28.6%) (see Table 4). One patient with a benign diagnosis also had a slightly elevated alkaline phosphatase level. The other 25 bones showed a variety of benign pathological processes, as shown in Table 4. Staging based solely on increased uptake on scintigraphy images would have led to a 78.1% false positive rate for diagnosing metastatic cancer.

Detection of area with increased tracer uptake was easily accomplished with the aid of the gamma-ray detection probe. The mean ratio of measured hotspot activity on the target rib compared with adjacent ribs or the same rib away from the hot spot was a mean 2.19 ± 1.05, with a median of 1.70, and a range of 1.22-5.67. This means that the localized area of increased uptake of tracer was over twice as hot as the surrounding bones. This difference was easily discernible intraoperatively. The newer generation of gamma counters with their highly colli-mated probes are even more precise with increased directionality. This gives even better and easier intraoperative discrimination of the hot spot with less background interference and higher count ratios. In the most recent 11 rib biopsies in which I used the collimated probes, the mean ratio of hot spot activity to background counts was clearly higher at 3.24 ± 1.18 (median 2.89), thereby allowing an even sharper differentiation between the targeted bone lesion and the adjacent normal bone.

There was no morbidity or mortality specifically associated with the intraoperative gamma-probe technique or the actual rib biopsies. And after experience was gained with this technique on a few patients, the total surgical time for these

Table 3 Results of Patients Undergoing Gamma Probe-Directed Bone Biopsy

No.

Age (yr)

Sex (M/F)

Clinical diagnosis

Symptoms

Bone scan uptake

Plain bone radiographs

Alk. phos. (normal values)

PSA (normal values)

Bone biopsied

Injection to surgery (hr)

Count ratio

Rib pathology

1

65

M

Carcinoma of

None

L 7th rib &

Normal

46

14.8

L 7th rib

12

1.43

Hypercellular

prostate

skull

(37-107)

(0-4.0)

marrow

2

44

F

Lymphoma

Vague chest

L ribs 6, 7,

Normal

294

L hth rib

12

1.42

Lymphoma

Pain (i yr.)

&8

(80-258)

L 8th rib

12

1.59

Lymphoma

3

62

M

Sq. cell ca.a of

None

R 9th rib, L

Normal

208

R hth rib

6

1.69

Metastatic sq. cell

lung

6th rib

(80-258)

carcinoma

4

74

M

Sq. cell ca. of

Pain in low

Spine, mult.c

Fracture

81

L hth rib

6

2.00

Paget's disease

lung

back

ribs bilat.d

T11 spine

(37-147)

L 8th rib

6

1.53

Paget's disease

5

73

M

Sq. cell ca. of

None

R 10th & 11th

Normal

94

Rlhth rib

6

1.57

Enchondroma

lung

ribs

(38-126)

R 11th rib

6

1.67

Enchondroma

6

70

M

Sq. cell ca. of

Vague chest

L 6th rib

Normal

68

L 6th rib

6

2.05

Enchondroma

lung

wall pain

(38-126)

7

37

F

Carcinoma of

None

Body of the

Normal

58

Body of the

6

1.22

Chondroma

breast

sternum

(38-126)

sternum

8

66

M

Carcinoma of

None

L 6th rib

Normal

57

14.3

L 6th rib

6

1.54

Metastatic prostate

prostate

(25-150)

(0.1-4.0)

ca.

9

54

F

Sq. cell ca. of

Vague chest

L 6th & 9th

Normal

52

L hh rib

6

1.74

Chondroma

lung

wall pain

ribs

(20-125)

L 9th rib

6

1.63

Chondroma

10

39

M

Melanoma

None

L 10th rib

Normal

52

Llhth rib

6

1.35

Localized fibrosis

(38-126)

granulation tissue

11

64

M

Large cell ca.

None

L 8th rib

Normal

62

L hth rib

6

1.47

Hypercellular

of lung

(38-126)

marrow

12

74

F

Carcinoma of

None

L 6th rib

Normal

54

L hth rib

6

1.71

Hypercell. e marrow;

breast

L 9th rib

(38-126)

osteosclerosis

13

54

F

Sm. cell ca.b of

Vague left ant

L 8th rib

Normal

87

L hth rib

6

1.31

Hypercell. marrow,

lung

chest pain

(38-126)

osteosclerosis

14

76

M

Renal cell car-

None

R 4th rib

Normal

75

2.5

L 7th rib

6

1.83

Fibrous dysplasia

cinoma

L 7th rib

(42-121)

(0.1-4.0)

15

45

F

No known ma

Vague L chest

R 9th rib

Normal

76

L 5th rib

6

2.69

Chondroma with

lignancy

wall pain

L 5th rib

(38-126)

healing fracture

16

82

M

Carcinoma of

None

L 4th rib

Normal

4th rib

6

1.62 L

ocal fibrosis; Re-

the lung

R 7th rib

mote fracture

17

53

M

Melanoma

Vague chest

R 6th rib

Irregular R

53

R 6th rib

6

1.40

Metastatiimela-

wall pain

6th rib

(38-126)

noma

18

55

F

Melanoma

Generalized

L 3rd rib

Normal

283

L 3rd rib

6

2.67

Benign bone remod-

bone pain

(80-253)

eling

19

67

F

Adenoca.f of

Vague chest

L 10th rib

Normal

93

L 10th rib

6

2.89

Metastatic adenocar-

the lung

wall pain

(38-126)

cinoma

20

50

F

Diffuse bone

Pain L 3rd rib

L 3rd rib

Normal

87

L 3rd rib

6

4.0

Bone remodeling

pain MM?

R 6th rib

(38-126)

with fibrosis

21

69

F

Small cell ca.

Diffuse chest

L 6th rib

Normal

81

L 6th rib

6

3.33

Bone remodeling;

of lung

tenderness

R 11th rib

(38-126)

Prior fracture

22

78

F

Mal. fibrous

Vague chest

R 5th rib

Normal

73

R 5th rib

6

5.67

Bone remodeling;

histiocytoma

wall pain

(48-183)

Cortical fracture

23

62

M

Ca. of the

None

L 8th rib

Normal

57

36.5

L 8th rib

6

1.98

Bone remodeling;

prostate

R 6th rib

(38-126)

(0.1-4.0)

Old fracture

24

66

M

Ca. of the

None

R 8th rib

Normal

74

6.1

R 8th rib

6

2.67

Bone remodeling;

prostate

(38-126)

(0.1-4.0)

Old fracture

25

39

F

Ca. of the

None

L 10th rib

Normal

95

L 10th rib

4

3.43

Enchondroma

breast

(38-126)

26

71

F

Adenoca. of

None

Multiple bilat-

Normal

87

L 5th rib

3

2.69

Hypercellularity;

the lung

eral ribs

(38-126)

Bone remodeling

27

52

F

Ca. of the

Chest tenderness

Multiple bilat-

Fracture 4th

80

L 10th rib

4

4.68

Enchondroma

breast

eral ribs

rib only

(38-126)

28

68

F

Adenoca. of

Vague chest

Multiple right

Old surg.

53

Rlhth rib

4

1.58

Bone remodeling;

the lung

wall pain

ribs

changes

(38-126)

Localized fibrosis

Abbreviations'. Alk. phos., alkaline phosphatase (units/L); PSA, prostate-specific antigen (ng/mL); MM, multiple myeloma; L, left; R, right. a Sq. cell ca., squamous cell carcinoma. b Sm. cell ca., small cell carcinoma. c Multiple. d Bilateral. e Hypercellular. f Adenoca., adenocarcinoma.

c if

Table 4 Specific Radioguided Bone Biopsy Diagnoses

Malignant Number

Table 4 Specific Radioguided Bone Biopsy Diagnoses

Malignant Number

Lung carcinoma (NSCLC)

3 (all had normal alk. phos.)

Lymphoma

2 (both had elevated alk. phos.)

Prostate carcinoma

1 (normal alk. phos., elevated PSA)

Melanoma

1 (normal alk. phos.)

Benign

Enchondroma/chondroma

9

Hypercellular marrow/osteosclerosis

5

Paget's disease

2

Fibrous dysplasia

1

Localized fibrosis/remote fracture

8

Total:

32

Abbreviations'. Alk. phos., alkaline phosphatase; PSA, prostate-specific antigen. Note: Alkaline phosphatase was normal in all but one patient with a benign diagnosis.

Abbreviations'. Alk. phos., alkaline phosphatase; PSA, prostate-specific antigen. Note: Alkaline phosphatase was normal in all but one patient with a benign diagnosis.

cases decreased to only 20-40 minutes. Intraoperative radiographs were eliminated and the counting technique is precise, rapid, and reproducible.

The most common benign abnormality found in this clinical series was a chondroma or enchondroma, accounting for 9 of 32 (36%) of biopsy results. This benign cartilaginous tumor is relatively common, representing 13.4% of all benign bone tumors. The actual incidence is unknown because they occur sporadically and are asymptomatic [15]. They tend to occur most commonly in the small bones of the hands and feet, but are also found in long, thin bones such as the ribs. Unless they become very large, these lesions remain asymptomatic and are not generally visible on plain bone radiographs. They are usually found incidentally as an area of increased uptake of radioisotope on a bone scan performed during the evaluation of a patient with a malignancy. A subsequent biopsy usually follows and the diagnosis of a benign chondroma is then made.

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